Evolution of Helicoverpa armigera resistance to Bacillus thuringiensis (Bt) cotton producing Cry1Ac is progressing in northern China, and replacement of Cry1Ac cotton by pyramided Bt cotton has been considered to counter such resistance. Here, we investigated four of the eight conditions underlying success of the refuge strategy for delaying resistance to Cry1Ac+Cry2Ab cotton, a pyramid that has been used extensively against H.armigera outside China. Laboratory bioassays of a Cry2Ab-selected strain (An2Ab) and a related unselected strain (An) reveal that resistance to Cry2Ab (130-fold) was nearly dominant, autosomally inherited, and controlled by more than one locus. Strong cross-resistance occurred between Cry2Ab and Cry2Aa (81-fold). Weaker cross-resistance (18- to 22-fold) between Cry2Ab and Cry1A toxins was also present and significantly increased survival of An2Ab relative to An on cotton cultivars producing the fusion protein Cry1Ac/Cry1Ab or Cry1Ac. Survival on Cry1Ac+Cry2Ab cotton was also significantly higher in An2Ab than in An, showing that redundant killing on this pyramid was incomplete. Survival on non-Bt cotton did not differ significantly between An2Ab and An, indicating an absence of fitness costs affecting this trait. These results indicate that a switch to three-toxin pyramided cotton could be valuable for increasing durability of Bt cotton in China.

A doença crestamento bacteriano comum do feijoeiro, causada pela bactéria Xanthomonas axonopodis pv. phaseoli, ocorre principalmente nas regiões quentes e úmidas do globo. A resistência induzida consiste no aumento da resistência da planta por meio da utilização de agentes externos, sem qualquer alteração em seu genoma. Os objetivos do trabalho foram: (i) verificar a indução de resistência em feijoeiro com o uso do indutor abiótico acibenzolar-S-metil (ASM) contra X. axonopodis pv. phaseoli em casa de vegetação e em campo; (ii) avaliar os parâmetros bioquímicos (carboidratos, proteínas, fenóis, clorofila e atividade da enzima peroxidase) e fisiológico (potencial hídrico) nas interações entre plantas de feijão induzidas com o indutor contra X. axonopodis pv. phaseoli; (iii) avaliar os custos da indução de resistência em função da aplicação do indutor contra X. axonopodis pv. phaseoli em plantas de feijão com base nos parâmetros bioquímicos, fisiológicos e de produção. Para isso, realizaram-se dois experimentos. Os tratamentos foram dispostos da seguinte maneira: Tratamento A Controle água, Tratamento B Controle ASM, Tratamento C Água com inoculação do patógeno ao 7º dias após a emergência das plântulas (dae) (experimento 1) e ao 21º dae (experimento 2), Tratamento D Induzida com ASM e desafiada com o patógeno ao 7º dae (experimento 1) e ao 21º dae (experimento 2). As pulverizações ocorreram, para o experimento 1, aos 0, 7, 14 e 28 dae, a inoculação foi realizada no 7º dae e foram realizadas quatro coletas das amostras aos 0, 7, 21 e 35 dae. Entretanto para o experimento 2, as pulverizações foram feitas aos 0, 7, 14, 28 e 42 dae, a inoculação foi realizada no 21º dae e as cinco coletas foram conduzidas aos 0, 7, 21, 35 e 49 dae. Foram observadas diferenças estatísticas tanto entre tratamentos quanto entre épocas de coleta, bem como na interação dos tratamentos com as diferentes épocas, dependendo do parâmetro observado. De maneira geral, as plantas tratadas com ASM quando comparadas com plantas controle água, bem como as plantas pré-tratadas com ASM e desafiadas com a bactéria quando comparadas com as plantas pulverizadas com água e inoculadas com o patógeno, apresentaram: a) teores de clorofila próximos; b) aumentaram os teores de fenóis, proteínas totais e peroxidase e c) diminuíram os valores de carboidratos totais. As plantas que apresentaram os valores mais negativos de potencial hídrico foram as pulverizadas com água e inoculadas com o patógeno, seguidas das plantas induzidas com ASM e desafiadas com o patógeno. O mesmo padrão ocorreu com relação à produtividade, onde água+patógeno apresentou a maior redução de massa seca, número de vagens/planta e peso de 100 grãos, seguidos de plantas induzidas com ASM e desafiadas com o patógeno, ASM e água, respectivamente. Porém o número de grãos/vagem não sofreu alteração. Houve indução de resistência nas plantas em função da aplicação com ASM, visto que a severidade da doença diminuiu nas mesmas. / The common bacterial blight disease of bean caused by the bacterium Xanthomonnas axonopodis pv. phaseoli, occurs mainly in hot and humid regions of the globe. The induced resistance consists in the increase of the plant resistance by the use of external agents, without any change in its genome. The objectives of this study were: (i) to verify the induction of resistance in bean plants by using the abiotic inducer acibenzolar-S-methyl (ASM) against Xanthomonas axonopodis pv. phaseoli in greenhouse and field conditions, (ii) to evaluate the biochemical parameters (carbohydrates, proteins, phenols, chlorophyll and peroxidase activity) and physiological (water potential) in the interactions between bean plants treated with the inducer against X. axonopodis pv. phaseoli; (iii) to evaluate the costs of the induction of resistance by on the basis of biochemical, physiological and production parameters. Thus, to achieve this purpose, two experiments were carried out. The treatments were arranged as follows: Treatment A - Control water; Treatment B - ASM Control; Treatment C - Water and inoculation 7 days after emergency (dae) of the seedlings (experiment 1) and 21 dae (Experiment 2); Treatment D - Induced with ASM and challenged with the pathogen 7 dae (experiment 1) and 21 dae (experiment 2). The treatments with ASM were made for experiment 1, at 0, 7, 14 and 28 dae, the inoculation was done 7 dae and four samples were collected at 0, 7, 21 and 35 dae. However, for the experiment 2, the treatments with ASM were made at 0, 7, 14, 28 and 42 days after seedling emergence, the inoculation was performed 21 dae and five samples were collected 0, 7, 21, 35 and 49 dae. Statistical differences were observed between treatments, among harvest dates, as well as the interaction of treatments with different harvests, depending on the parameter observed. In general, plants treated with ASM when compared to plants control, as well as plants pretreated with ASM and challenged with the bacteria when compared to plants sprayed with water and inoculated with the pathogen, showed: a) the amount of chlorophyll was close; b) increased levels of phenolics, proteins and peroxidase; c) decreased values of carbohydrate. Plants that showed the more negative water potential were plants sprayed with water and inoculated with the pathogen, followed by plants induced with ASM and challenged with the pathogen. The same pattern occurred with productivity, plants sprayed with water and inoculated with the pathogen exhibited the higgest reduction in dry weight, number of pods per plant and 100 grain weight, followed by plants induced with ASM and challenged with the pathogen, ASM and water, respectively. In all treatments, the number of grains per pods did not change. Finally, there was induction of resistance in plants by ASM application since the disease severity decreased.

Based on surface area, South Africa is currently ranked 8th in planting genetically modified (GM) crops in the world. The stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is of economic importance throughout sub–Saharan Africa. Bt maize (MON810) has been grown to control lepidopterous stem borers in South Africa since its first release in 1998. The first report of resistance to Bt maize was made in the Christiana area of South Africa in 2007. The objectives of this study were to evaluate the status of resistance of populations of B. fusca to Bt maize; to evaluate farmers' perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how the field situation developed between 1998 and 2010; to compare the fitness of the fertility, fecundity and longevity of Bt–resistant and susceptible B. fusca populations and to determine if there are fitness costs associated with resistance of B. fusca to Bt maize. Questionnaire surveys were conducted amongst 185 farmers in seven districts throughout the maize production region. The questionnaire addressed signing of contracts upon purchasing GM seed, refuge compliance, pest management practices, perceived benefits and risks relating to Bt maize. In order to study fitness and fitness costs that may be associated with resistance development, the life history parameters of known Bt–resistant and susceptible populations were compared in the laboratory using a diapauses–as well as second–generation populations collected in maize fields. The following parameters were compared between different stem borers populations and treatments: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810) and that larvae collected from refugia at Vaalharts were resistant and survived on Bt maize. Compliance to refugia requirements was low especially during the initial 5 – 7 years after release. An alarmingly high number of farmers applied insecticides as preventative sprays on Bt maize and refugia. Except for moth longevity and LT50– values, no other fitness costs were observed to be associated with the resistance trait in the highly resistant B. fusca population used in this study. The LT50 may indicate some degree of fitness cost but does not translate into observable costs in terms of fecundity, larval mass and survival. The absence of fitness costs may promote the use of alternative Bt–resistance management strategies, such as the introduction of a multigene strategy. The introduction of a stacked event such as MON89034 which produces more than one protein with activity active against the resistant target pest, together with compliance to the refuge strategy, is most likely the only solution to managing Btresistant stem borer populations in South Africa. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Based on surface area, South Africa is currently ranked 8th in planting genetically modified (GM) crops in the world. The stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is of economic importance throughout sub–Saharan Africa. Bt maize (MON810) has been grown to control lepidopterous stem borers in South Africa since its first release in 1998. The first report of resistance to Bt maize was made in the Christiana area of South Africa in 2007. The objectives of this study were to evaluate the status of resistance of populations of B. fusca to Bt maize; to evaluate farmers' perceptions of the regulatory aspects guiding the planting of Bt maize and refugia and how the field situation developed between 1998 and 2010; to compare the fitness of the fertility, fecundity and longevity of Bt–resistant and susceptible B. fusca populations and to determine if there are fitness costs associated with resistance of B. fusca to Bt maize. Questionnaire surveys were conducted amongst 185 farmers in seven districts throughout the maize production region. The questionnaire addressed signing of contracts upon purchasing GM seed, refuge compliance, pest management practices, perceived benefits and risks relating to Bt maize. In order to study fitness and fitness costs that may be associated with resistance development, the life history parameters of known Bt–resistant and susceptible populations were compared in the laboratory using a diapauses–as well as second–generation populations collected in maize fields. The following parameters were compared between different stem borers populations and treatments: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. This study confirmed resistance of B. fusca to the Cry1Ab toxin (MON810) and that larvae collected from refugia at Vaalharts were resistant and survived on Bt maize. Compliance to refugia requirements was low especially during the initial 5 – 7 years after release. An alarmingly high number of farmers applied insecticides as preventative sprays on Bt maize and refugia. Except for moth longevity and LT50– values, no other fitness costs were observed to be associated with the resistance trait in the highly resistant B. fusca population used in this study. The LT50 may indicate some degree of fitness cost but does not translate into observable costs in terms of fecundity, larval mass and survival. The absence of fitness costs may promote the use of alternative Bt–resistance management strategies, such as the introduction of a multigene strategy. The introduction of a stacked event such as MON89034 which produces more than one protein with activity active against the resistant target pest, together with compliance to the refuge strategy, is most likely the only solution to managing Btresistant stem borer populations in South Africa. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Protein synthesis is a complex process performed by sophisticated cellular particles known as ribosomes. Although RNA constitutes the major structural and functional component, ribosomes from all kingdoms contain an extensive array of proteins with largely undefined functional roles. The work presented in this thesis addresses ribosomal complexity using mutants of Salmonella typhimurium to examine the physiological effects of ribosomal protein (r-protein) removal and orthologous replacement on bacterial fitness and ribosome function. The results of paper I demonstrate that removal of small subunit protein S20 conferred two independent translation initiation defects: (i) a significant reduction in the rate and extent of mRNA binding and (ii) a drastic decrease in the yield of 70S complexes caused by an impairment in subunit association. The topographical location of S20 in mature 30S subunits suggests that these perturbations are the result of improper orientation of helix 44 of the 16S rRNA when S20 is absent. In paper II we show that the major functional impairment associated with loss of large subunit protein L1 manifested as an increase in free ribosomal subunits at the expense of translationally active 70S particles. Furthermore, the formation of free ribosomal subunits was imbalanced suggesting that L1 is required to suppress degradation or promote formation of 30S subunits. Compensatory evolution revealed that mutations in other large subunit proteins mitigate the cost of L1 removal, in one case seemingly via an increase in 70S complex formation. As shown in paper III, the large fitness costs associated with complete removal of r-proteins is in contrast to the generally mild costs of orthologous protein replacement, even in the absence of a high degree of homology to the native protein. This clearly demonstrates the robustness and plasticity of the ribosome and protein synthesis in general and it also implies that functional constraints are highly conserved between these proteins. The findings of paper III also allowed us to examine the barriers that constrain horizontal gene transfer and we find that increased gene dosage of the sub-optimal heterologous protein may be an initial response to stabilize deleterious transfer events. Overall the results highlight the requirement of r-proteins for the maintenance of ribosomal structural integrity.

A doença crestamento bacteriano comum do feijoeiro, causada pela bactéria Xanthomonas axonopodis pv. phaseoli, ocorre principalmente nas regiões quentes e úmidas do globo. A resistência induzida consiste no aumento da resistência da planta por meio da utilização de agentes externos, sem qualquer alteração em seu genoma. Os objetivos do trabalho foram: (i) verificar a indução de resistência em feijoeiro com o uso do indutor abiótico acibenzolar-S-metil (ASM) contra X. axonopodis pv. phaseoli em casa de vegetação e em campo; (ii) avaliar os parâmetros bioquímicos (carboidratos, proteínas, fenóis, clorofila e atividade da enzima peroxidase) e fisiológico (potencial hídrico) nas interações entre plantas de feijão induzidas com o indutor contra X. axonopodis pv. phaseoli; (iii) avaliar os custos da indução de resistência em função da aplicação do indutor contra X. axonopodis pv. phaseoli em plantas de feijão com base nos parâmetros bioquímicos, fisiológicos e de produção. Para isso, realizaram-se dois experimentos. Os tratamentos foram dispostos da seguinte maneira: Tratamento A Controle água, Tratamento B Controle ASM, Tratamento C Água com inoculação do patógeno ao 7º dias após a emergência das plântulas (dae) (experimento 1) e ao 21º dae (experimento 2), Tratamento D Induzida com ASM e desafiada com o patógeno ao 7º dae (experimento 1) e ao 21º dae (experimento 2). As pulverizações ocorreram, para o experimento 1, aos 0, 7, 14 e 28 dae, a inoculação foi realizada no 7º dae e foram realizadas quatro coletas das amostras aos 0, 7, 21 e 35 dae. Entretanto para o experimento 2, as pulverizações foram feitas aos 0, 7, 14, 28 e 42 dae, a inoculação foi realizada no 21º dae e as cinco coletas foram conduzidas aos 0, 7, 21, 35 e 49 dae. Foram observadas diferenças estatísticas tanto entre tratamentos quanto entre épocas de coleta, bem como na interação dos tratamentos com as diferentes épocas, dependendo do parâmetro observado. De maneira geral, as plantas tratadas com ASM quando comparadas com plantas controle água, bem como as plantas pré-tratadas com ASM e desafiadas com a bactéria quando comparadas com as plantas pulverizadas com água e inoculadas com o patógeno, apresentaram: a) teores de clorofila próximos; b) aumentaram os teores de fenóis, proteínas totais e peroxidase e c) diminuíram os valores de carboidratos totais. As plantas que apresentaram os valores mais negativos de potencial hídrico foram as pulverizadas com água e inoculadas com o patógeno, seguidas das plantas induzidas com ASM e desafiadas com o patógeno. O mesmo padrão ocorreu com relação à produtividade, onde água+patógeno apresentou a maior redução de massa seca, número de vagens/planta e peso de 100 grãos, seguidos de plantas induzidas com ASM e desafiadas com o patógeno, ASM e água, respectivamente. Porém o número de grãos/vagem não sofreu alteração. Houve indução de resistência nas plantas em função da aplicação com ASM, visto que a severidade da doença diminuiu nas mesmas. / The common bacterial blight disease of bean caused by the bacterium Xanthomonnas axonopodis pv. phaseoli, occurs mainly in hot and humid regions of the globe. The induced resistance consists in the increase of the plant resistance by the use of external agents, without any change in its genome. The objectives of this study were: (i) to verify the induction of resistance in bean plants by using the abiotic inducer acibenzolar-S-methyl (ASM) against Xanthomonas axonopodis pv. phaseoli in greenhouse and field conditions, (ii) to evaluate the biochemical parameters (carbohydrates, proteins, phenols, chlorophyll and peroxidase activity) and physiological (water potential) in the interactions between bean plants treated with the inducer against X. axonopodis pv. phaseoli; (iii) to evaluate the costs of the induction of resistance by on the basis of biochemical, physiological and production parameters. Thus, to achieve this purpose, two experiments were carried out. The treatments were arranged as follows: Treatment A - Control water; Treatment B - ASM Control; Treatment C - Water and inoculation 7 days after emergency (dae) of the seedlings (experiment 1) and 21 dae (Experiment 2); Treatment D - Induced with ASM and challenged with the pathogen 7 dae (experiment 1) and 21 dae (experiment 2). The treatments with ASM were made for experiment 1, at 0, 7, 14 and 28 dae, the inoculation was done 7 dae and four samples were collected at 0, 7, 21 and 35 dae. However, for the experiment 2, the treatments with ASM were made at 0, 7, 14, 28 and 42 days after seedling emergence, the inoculation was performed 21 dae and five samples were collected 0, 7, 21, 35 and 49 dae. Statistical differences were observed between treatments, among harvest dates, as well as the interaction of treatments with different harvests, depending on the parameter observed. In general, plants treated with ASM when compared to plants control, as well as plants pretreated with ASM and challenged with the bacteria when compared to plants sprayed with water and inoculated with the pathogen, showed: a) the amount of chlorophyll was close; b) increased levels of phenolics, proteins and peroxidase; c) decreased values of carbohydrate. Plants that showed the more negative water potential were plants sprayed with water and inoculated with the pathogen, followed by plants induced with ASM and challenged with the pathogen. The same pattern occurred with productivity, plants sprayed with water and inoculated with the pathogen exhibited the higgest reduction in dry weight, number of pods per plant and 100 grain weight, followed by plants induced with ASM and challenged with the pathogen, ASM and water, respectively. In all treatments, the number of grains per pods did not change. Finally, there was induction of resistance in plants by ASM application since the disease severity decreased.

Mefenoxam has been a premier compound for Phytophthora disease control in the nursery industry for 30 years. The primary objectives of this research were to examine whether Phytophthora species have developed resistance to this compound and to investigate fungicide resistance management strategies. Phytophthora nicotianae, a destructive pathogen of numerous herbaceous and some woody ornamental plants, was used as a model system. P. cinnamomi, a major pathogen of a wide range of tree species and shrub plants, was also included for comparison. Twenty-six isolates of P. nicotianae were highly resistant to mefenoxam with a mean EC50 value of 326.5 µg/ml while the remaining 70 were sensitive with an EC50 of <0.01 µg/ml (Label rate: 0.08µg/ml). All resistant isolates were recovered from herbaceous annuals and irrigation water in 3 Virginia nurseries. Resistant isolates were compared with sensitive ones using seedlings of Lupinus "Russell Hybrids" in the absence of mefenoxam for relative competitive ability. Resistant isolates out-competed sensitive ones within 3 to 6 sporulation cycles. Resistant isolates exhibited greater infection rate and higher sporulation ability than sensitive ones. No mefenoxam resistant isolates were identified in P. cinnamomi. All 65 isolates of P. cinnamomi were sensitive to mefenoxam with an EC50 of < 0.04 ï ­g/ml. Attempts to generate mutants with high resistance to mefenoxam through UV mutagenesis and mycelial adaptation were not successful. However, there were significant reductions in sensitivity to mefenoxam; those slightly resistant mutants carried fitness penalties, which may explain why P. cinnamomi remains sensitive to mefenoxam. The effect of propamocarb hydrochloride on different growth stages of Phytophthora nicotianae was evaluated in search for an alternative fungicide. Propamocarb greatly inhibited sporangium production, zoospore motility, germination and infection. However, it has little inhibition of mycelial growth and infections. Propamocarb can be used as an alternative fungicide to mefenoxam where mefenoxam resistance has become problematic. However, it must be used preventively; i.e. before infections occur. The genetic inheritance of mefenoxam resistance in P. nicotianae was studied using F1 progenies of a cross between resistant and sensitive isolates. The F1 progenies segregated for mefenoxam resistance in ratio of 1R:1S, indicating the mefenoxam resistance is controlled by a single dominant gene. One RAPD marker putatively linked to resistant locus in repulsion phase was obtained by bulked segregant analysis and was converted to the SCAR marker. This marker is capable of differentiating mefenoxam resistant populations from sensitive populations included in this study. / Ph. D.

A indução de resistência envolve a ativação de mecanismos de defesa latentes existentes nas plantas em resposta ao tratamento com agentes bióticos ou abióticos. As plantas apresentam sistema de defesa induzível, com a finalidade de economizar energia. Desse modo, a resistência induzida em condições naturais representará custo apenas na presença do patógeno. Porém, plantas que investem seus recursos para se defenderem na ausência de patógenos arcarão com custos que refletirão na produtividade, uma vez que as alterações metabólicas que levam a resistência apresentam custo adaptativo associado, o qual pode pesar mais do que o benefício. O efeito negativo na produtividade ocorre principalmente onde indutores químicos são utilizados repetidas vezes ou em doses mais elevadas. Assim, em alguns casos podemos estar caminhando sobre uma estreita linha entre custo e benefício, onde a cura pode ser tão ruim quanto a própria doença. Neste trabalho foram conduzidos experimentos objetivando verificar alterações bioquímicas e fisiológicas, correlacionando-as com parâmetros de produção do feijoeiro entre a indução mediada por acibenzolar-S-metil (ASM), indutor químico, e, a mediada por Bacillus cereus, indutor biológico, antes da chegada do patógeno. Para tanto, foram avaliados plantas de feijão, induzidas por esses dois indutores e desafiadas com Xanthomonas axonopodis pv. phaseoli, para constatar a ocorrência do fenômeno da indução de resistência. Na ausência do patógeno, foram avaliados os parâmetros fisiológicos respiração e fotossíntese, determinada a atividade de enzimas envolvidas no processo de defesa como peroxidase, quitinase, &#946;-1,3-glucanase, fenilalanina amônia-liase e polifenoloxidase e a atividade de enzimas envolvidas no catabolismo como proteases, a síntese de compostos do metabolismo secundário como fenóis totais e lignina, a síntese de compostos do metabolismo primário como proteínas e açúcares redutores. Também se avaliou o crescimento das plantas, a produtividade e parâmetros de produção e alguns parâmetros de qualidade dos grãos. Observou-se a ocorrência da indução de resistência em função da aplicação dos dois indutores utilizados, porém para o indutor ASM a indução de resistência estava associada a aumentos na atividade de peroxidase, quitinase, &#946;-1,3-glucanase e proteases, aumento da síntese de lignina e redução no teor de fenóis, aumentos no teor de proteínas solúveis e de açúcares redutores nas folhas, redução do crescimento e da produtividade, aumento do teor de proteína dos grãos e redução do teor de amido nestes. Já o B. cereus apenas ocasionou aumento na atividade de peroxidase de forma atenuada e tendeu a aumentar a atividade de proteases, e reduzir o teor de proteínas nas folhas sem interferir no crescimento ou na produtividade, mas reduziu o teor de proteína dos grãos, mas aumentou o teor de amido nestes. Portanto, o indutor B. cereus , aparentemente alterou muito pouco o metabolismo do feijoeiro, sem interferir na produtividade e melhorando a qualidade da produção, enquanto que o indutor abiótico ASM alterou muito mais seu metabolismo, gerando um custo metabólico e redirecionando os fotoassimilados para investir em defesas, a custo da redução da produtividade. / The induction of systemic resistance involves the activation of latent resistance mechanisms in plants against pathogens in response to the treatment with biotic or abiotic agents. The plants present latent defense system that can be activated with the goal of saving energy. Thus, the induced resistance under natural conditions will represent cost only in the pathogen presence. In this way, plants that invest their resources to defend themselves in the absence of the pathogen will pay off with costs that will reflect in productivity, since the metabolic changes that led to resistance have associated fitness cost which could outweigh the benefit. The negative effects on plant productivity usually occur when chemical inducers are used repeatedly or in higher doses, mainly in the absence of the pathogen. Thus, we can say that in some cases we can be walking on a fine line between cost and benefit, where the cure may be as bad as the disease itself. In this work, experiments were carry out to verify biochemical and physiologic alterations, correlating them with production parameters of bean plants treated with acibenzolar-S-methyl (ASM), chemical inducer, or Bacillus cereus , biological inducer, before the pathogen arrival. Initially, bean plants were evaluated for induced resistance against Xanthomonas axonopodis pv. phaseoli when treated with the two inducers. In the absence of the pathogen, it was evaluated the physiological parameters respiration and photosynthesis and the activity of enzymes involved in the defense as peroxidase, chitinase, &#946;-1,3-glucanase, phenylalanine ammonia-lyase and polifenoloxidase and activity of enzymes involved in the catabolism as proteases, and the synthesis of compounds of the secondary metabolism as phenols and lignin, and the synthesis of compounds of the primary metabolism as proteins and sugars. The growth of the plants was evaluated as well as their productivity and production parameters. Some quality parameters of the grains were also evaluated. The occurrence of the resistance induced in the bean plants against the pathogens was observed for the two inducers. However, for the ASM the resistance induced was associated to increases in peroxidase, chitinase and &#946;-1,3-glucanase activities, increase in the protease activity, increase in lignin synthesis and reduction in the phenol content, increase in soluble proteins and sugar content in the leaves, reduction of the growth and productivity, increasing the protein and reducing the starch content of the grains. The B. cereus only increased peroxidase activity in a lower way and showed a tendency to increase protease activity, and to reduce the protein content in the leaves without interfering in the growth or in the productivity, but it reduced the protein content and it increased the starch content of the grains. Therefore, the biotic inducer, B. cereus altered a minimum the metabolism of the bean plant, without interfering in the productivity and improving the quality of the production, while the abiotic inducer ASM altered its metabolism, generating a metabolic cost and consuming the plant photosyntathes to invest in defenses, causing a reduction in the productivity.

A indução de resistência envolve a ativação de mecanismos de defesa latentes existentes nas plantas em resposta ao tratamento com agentes bióticos ou abióticos. As plantas apresentam sistema de defesa induzível, com a finalidade de economizar energia. Desse modo, a resistência induzida em condições naturais representará custo apenas na presença do patógeno. Porém, plantas que investem seus recursos para se defenderem na ausência de patógenos arcarão com custos que refletirão na produtividade, uma vez que as alterações metabólicas que levam a resistência apresentam custo adaptativo associado, o qual pode pesar mais do que o benefício. O efeito negativo na produtividade ocorre principalmente onde indutores químicos são utilizados repetidas vezes ou em doses mais elevadas. Assim, em alguns casos podemos estar caminhando sobre uma estreita linha entre custo e benefício, onde a cura pode ser tão ruim quanto a própria doença. Neste trabalho foram conduzidos experimentos objetivando verificar alterações bioquímicas e fisiológicas, correlacionando-as com parâmetros de produção do feijoeiro entre a indução mediada por acibenzolar-S-metil (ASM), indutor químico, e, a mediada por Bacillus cereus, indutor biológico, antes da chegada do patógeno. Para tanto, foram avaliados plantas de feijão, induzidas por esses dois indutores e desafiadas com Xanthomonas axonopodis pv. phaseoli, para constatar a ocorrência do fenômeno da indução de resistência. Na ausência do patógeno, foram avaliados os parâmetros fisiológicos respiração e fotossíntese, determinada a atividade de enzimas envolvidas no processo de defesa como peroxidase, quitinase, &#946;-1,3-glucanase, fenilalanina amônia-liase e polifenoloxidase e a atividade de enzimas envolvidas no catabolismo como proteases, a síntese de compostos do metabolismo secundário como fenóis totais e lignina, a síntese de compostos do metabolismo primário como proteínas e açúcares redutores. Também se avaliou o crescimento das plantas, a produtividade e parâmetros de produção e alguns parâmetros de qualidade dos grãos. Observou-se a ocorrência da indução de resistência em função da aplicação dos dois indutores utilizados, porém para o indutor ASM a indução de resistência estava associada a aumentos na atividade de peroxidase, quitinase, &#946;-1,3-glucanase e proteases, aumento da síntese de lignina e redução no teor de fenóis, aumentos no teor de proteínas solúveis e de açúcares redutores nas folhas, redução do crescimento e da produtividade, aumento do teor de proteína dos grãos e redução do teor de amido nestes. Já o B. cereus apenas ocasionou aumento na atividade de peroxidase de forma atenuada e tendeu a aumentar a atividade de proteases, e reduzir o teor de proteínas nas folhas sem interferir no crescimento ou na produtividade, mas reduziu o teor de proteína dos grãos, mas aumentou o teor de amido nestes. Portanto, o indutor B. cereus , aparentemente alterou muito pouco o metabolismo do feijoeiro, sem interferir na produtividade e melhorando a qualidade da produção, enquanto que o indutor abiótico ASM alterou muito mais seu metabolismo, gerando um custo metabólico e redirecionando os fotoassimilados para investir em defesas, a custo da redução da produtividade. / The induction of systemic resistance involves the activation of latent resistance mechanisms in plants against pathogens in response to the treatment with biotic or abiotic agents. The plants present latent defense system that can be activated with the goal of saving energy. Thus, the induced resistance under natural conditions will represent cost only in the pathogen presence. In this way, plants that invest their resources to defend themselves in the absence of the pathogen will pay off with costs that will reflect in productivity, since the metabolic changes that led to resistance have associated fitness cost which could outweigh the benefit. The negative effects on plant productivity usually occur when chemical inducers are used repeatedly or in higher doses, mainly in the absence of the pathogen. Thus, we can say that in some cases we can be walking on a fine line between cost and benefit, where the cure may be as bad as the disease itself. In this work, experiments were carry out to verify biochemical and physiologic alterations, correlating them with production parameters of bean plants treated with acibenzolar-S-methyl (ASM), chemical inducer, or Bacillus cereus , biological inducer, before the pathogen arrival. Initially, bean plants were evaluated for induced resistance against Xanthomonas axonopodis pv. phaseoli when treated with the two inducers. In the absence of the pathogen, it was evaluated the physiological parameters respiration and photosynthesis and the activity of enzymes involved in the defense as peroxidase, chitinase, &#946;-1,3-glucanase, phenylalanine ammonia-lyase and polifenoloxidase and activity of enzymes involved in the catabolism as proteases, and the synthesis of compounds of the secondary metabolism as phenols and lignin, and the synthesis of compounds of the primary metabolism as proteins and sugars. The growth of the plants was evaluated as well as their productivity and production parameters. Some quality parameters of the grains were also evaluated. The occurrence of the resistance induced in the bean plants against the pathogens was observed for the two inducers. However, for the ASM the resistance induced was associated to increases in peroxidase, chitinase and &#946;-1,3-glucanase activities, increase in the protease activity, increase in lignin synthesis and reduction in the phenol content, increase in soluble proteins and sugar content in the leaves, reduction of the growth and productivity, increasing the protein and reducing the starch content of the grains. The B. cereus only increased peroxidase activity in a lower way and showed a tendency to increase protease activity, and to reduce the protein content in the leaves without interfering in the growth or in the productivity, but it reduced the protein content and it increased the starch content of the grains. Therefore, the biotic inducer, B. cereus altered a minimum the metabolism of the bean plant, without interfering in the productivity and improving the quality of the production, while the abiotic inducer ASM altered its metabolism, generating a metabolic cost and consuming the plant photosyntathes to invest in defenses, causing a reduction in the productivity.