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Bibliography: leaves 189-202 / 209 leaves : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The object of this thesis was to obtain information relevant to the development of peanut production in southern Australia... The results showed the importance of spatial arrangement and plant density when trying to optimise yield potential. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 2000

Field and greenhouse studies were conducted to assess the effects of row-spacing on diseases, weed control, herbicide persistence and plant development in peanut. Tebuconazole, when averaged across cultivars and row spacing, effectively controlled white mold (57%) and rust (58%). Azoxystrobin also controlled white mold (58%) and controlling rust (44%). Both fungicides reduced leaf spot severity in the conventional and twin rows when compared to untreated plots. Twin rows showed a 10% yield increase compared to the conventional planting. Both diclosulam and imazapic, when applied to twin rows at the full and reduced rate, provided better yellow nutsedge control than when applied to the conventional row. Twin rows yielded higher than the conventional rows when averaged across herbicides in one year. All full rate herbicide treatments enhanced yield over the untreated check. Diclosulam and imazapic treated soil sampled 60 DAP adversely affected all four crops. The advantage of planting peanuts in twin rows to reduce diclosulam and imazapic residual concentrations was not apparent. Georgia Green and Tamrun 96 planted in twin rows at three of the four locations in 1999 and 2000 yielded higher than peanuts planted in conventional rows. Yields were comparable to twin-row spacings that had higher plant densities. Georgia Green and Tamrun 96 planted in conventional rows, in most cases, had higher yields than narrow-rows. Measurements for plant diameter, pod distribution, and main stem length were higher with Tamrun 96 at most row spacings and planting densities compared to the respective Georgia Green planting densities and row spacings. Both cultivars when planted in twin or narrow rows at all planting densities did not enhance maturity when sampled late season. Georgia Green and Tamrun 96 when planted in conventional rows had the most pods/plant compared to the narrow and twin row spacing. No clear evidence was found to suggest that peanuts grown in narrow or twin rows increased white mold disease incidence. Grades for Georgia Green were higher than Tamrun 96 when planted in twin rows at the standard planting density. Tamrun 96 in twin rows at the standard planting density had a higher grade than when planted in conventional rows at the low planting density.

Field and greenhouse studies were conducted to assess the effects of row-spacing on diseases, weed control, herbicide persistence and plant development in peanut. Tebuconazole, when averaged across cultivars and row spacing, effectively controlled white mold (57%) and rust (58%). Azoxystrobin also controlled white mold (58%) and controlling rust (44%). Both fungicides reduced leaf spot severity in the conventional and twin rows when compared to untreated plots. Twin rows showed a 10% yield increase compared to the conventional planting. Both diclosulam and imazapic, when applied to twin rows at the full and reduced rate, provided better yellow nutsedge control than when applied to the conventional row. Twin rows yielded higher than the conventional rows when averaged across herbicides in one year. All full rate herbicide treatments enhanced yield over the untreated check. Diclosulam and imazapic treated soil sampled 60 DAP adversely affected all four crops. The advantage of planting peanuts in twin rows to reduce diclosulam and imazapic residual concentrations was not apparent. Georgia Green and Tamrun 96 planted in twin rows at three of the four locations in 1999 and 2000 yielded higher than peanuts planted in conventional rows. Yields were comparable to twin-row spacings that had higher plant densities. Georgia Green and Tamrun 96 planted in conventional rows, in most cases, had higher yields than narrow-rows. Measurements for plant diameter, pod distribution, and main stem length were higher with Tamrun 96 at most row spacings and planting densities compared to the respective Georgia Green planting densities and row spacings. Both cultivars when planted in twin or narrow rows at all planting densities did not enhance maturity when sampled late season. Georgia Green and Tamrun 96 when planted in conventional rows had the most pods/plant compared to the narrow and twin row spacing. No clear evidence was found to suggest that peanuts grown in narrow or twin rows increased white mold disease incidence. Grades for Georgia Green were higher than Tamrun 96 when planted in twin rows at the standard planting density. Tamrun 96 in twin rows at the standard planting density had a higher grade than when planted in conventional rows at the low planting density.

The fungi Sclerotinia minor and S. sclerotiorum are the causal agents of two similar diseases of peanut (Arachis hypogaea L.). Both diseases cause significant losses in the Australian peanut industry. Chemical and cultural control methods will not provide complete control. Development of cultivars with resistance to Sclerotinia will be an important component of integrated control. The capacity to breed and select for such resistance efficiently must be established before serious investment of resources is made to develop Sclerotinia resistant cultivars. The aims of this project are: (1) to generate information that will assist in the improvement of Sclerotinia resistance in peanut; (2) to develop screening techniques; (3) to identify Sclerotinia resistant peanut germplasm; (4) to understand the inheritance and estimate heritability of resistance to S. minor; (5) to assess response to selection for resistance; and (6) to test the effectiveness of identified sources of resistance against both S. minor and S. sclerotiorum. Experiments were conducted to develop screening techniques applicable for this project and a full scale breeding program. A previously unpublished technique for evaluating physiological resistance was described and modified. The artificial inoculation technique using colonised bean pod segments was found to be more robust than using colonised agar disks: discriminating among the physiological resistance of peanut genotypes to Sclerotinia whether used in controlled environment cabinets or the simple tent structures, and working well with both whole plants and detached stems. Cultivars and lines with the shortest lesion length in this test have demonstrated resistance to S. minor in field experiments in both Australia and in the USA. The use of a tent structure in place of a controlled environment cabinet (CEC) to create a high humidity environment allowed larger numbers of individuals to be tested at one time. With this technique, glasshouse space and labour costs, rather than the size of the available CECs, are the limits to the number of individuals that can be tested at one time. This will allow mass screening of segregating populations or replicated testing of progenies in a breeding program context that would not be possible with limited CEC facilities. Calculating a Moderated Lesion Length (MLL) by eliminating the failed or very small lesions was found to improve precision in measuring resistance responses of genotypes. Compared to average lesion length, the MLL had a stronger association with foci count (FC), a measure of resistance in the field. In cases where the small lesions do not occur independently of peanut genotype, a small lesion count (SLC) can be used to describe that variation. The detached stem technique examined in this thesis was another useful tool for screening, particularly in situations where seed production by the plants is deemed critical, or where the seed quantity available would not provide sufficient replication for the pot-based glasshouse test. This study has clearly established that material which shows resistance to S. minor in the USA, is resistant to S. minor and quite likely to be resistant to S. sclerotiorum in Australia. The high level of resistance to both S. minor and S. sclerotiorum in germplasm from Texas, particularly TxAG-4, was confirmed. The component lines of Virginia 93 Bunch showed good resistance in the field, which is primarily architectural resistance. Physiological resistance to S. minor was also identified in a cultivar and a landrace from Indonesia and three rust resistant breeding lines from Queensland. All germplasm found to have high physiological resistance to S. minor belonged to the Spanish type. Inheritance of physiological resistance to S. minor was studied using a Generation Means Analysis (GMA) of the cross TxAG-4/VA 861102 and its reciprocal. The broad-sense heritability of physiological resistance on a single plant basis was estimated at 47%, much higher than earlier estimates obtained in field studies. The average gene action of Sclerotinia resistance genes from TxAG-4 was found to be additive. No dominance effects were detected in the GMA. A small but significant reciprocal effect between TxAG-4 and VA 861102 indicated that VA 861102 passed on some physiological resistance maternally. Selection of single F2 and F3 plants successfully achieved an improvement in physiological resistance as measured by MLL. Selection was based on both MLL and seed production and further work should be conducted to quantify the comparative contribution of these two criteria. To estimate a realised heritability of physiological resistance in early generation selection it may be necessary to use a detached stem technique so that seed production occurs independently of expression of disease resistance. Successful selection of highly resistant genotypes from small F2 and F3 populations was taken as a possible indication of oligogenic control of resistance. An experiment was conducted to confirm the value of resistance against both S. minor and S. sclerotiorum. TxAG-4 was found to have physiological resistance to both S. minor and S. sclerotiorum. This resistance was expressed against both Sclerotinia species by progeny that were selected for resistance to S. minor. On the basis of the information obtained, the comparative advantages of three strategies for Sclerotinia resistant cultivar development are described: (1) introduction of germplasm; (2) recurrent backcrossing with screening and crossing in the BCnF1 generation; and (3) pedigree selection. At present introduction and backcrossing are recommended as the preferred strategies. Pedigree selection for Sclerotinia resistance is expected to become increasingly valuable after the development, by introduction and backcrossing, of Sclerotinia resistant cultivars with other desirable

Studies were conducted in small-plot and onarm environments in Mississippi in 2018 and 2019 to determine the effect of prohexadione calcium growth regulator on the growth and yield of peanut [Arachis hypogaea (L.)]. Onarm trials conducted in 2018 and 2019 concluded that in situations where the application of prohexadione calcium increased yield, variation in application rate had no effect on yield. Yields of peanut where any rate of prohexadione calcium was applied were 415 kg ha-1 greater than yields of peanut where prohexadione calcium were not applied. The addition of other agrichemicals had no effect on the efficacy of prohexadione calcium. Small-plot research in 2019 concluded that no rate variation had any effect on the growth or yield of peanut, and also concluded that alternative application timing methods had no effect on yield or growth of peanut.

Peanut skin, a low-value agriculture waste product, has drawn lots of research interest in recent years, due to its high content of A-type proanthocyanidins. A-type proanthocyanidins have been believed to contribute to cranberries' anti-UTI (urinary tract infection) effect. In this study, we compared the A-type proanthocyanidins in cranberry and peanut skin crude extracts using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Many similarities were found in the proanthocyanidin composition of cranberries and peanut skins. New oligomeric and polymeric proanthocyanidins in peanut skins, including heteroproanthocyanidins and proanthocyanidins with sugar moieties or galloyl esters, were tentatively identified. Solid phase extraction (SPE) and HPLC fractionation largely improved MALDI-TOF's ability to detect proanthocyanidins with high degrees of polymerization (DP). By analyzing the identified compounds in each fraction, we were also able to find some interesting elution pattern of the proanthocyanidins on the SPE cartridges and on the HPLC column. For example, the elution order on both the SPE cartridges and the diol phase column generally followed the DP. A-type proanthocyanidins tended to elute earlier than the B-type. Prodelphinidins retained much longer than other proanthocyanidins with the same DP. These findings may help researcher to identify future research directions and develop new separation methods to facilitate the identification of bioactive components in proanthocyanidin-rich plant extracts. / Ph. D.

The thesis entitled “Folding studies on Peanut Agglutinin: A lectin with an unusual quaternary structure” deals with the several aspects of the folding of the tetrameric legume lectin Peanut Agglutinin (PNA). PNA is a well studied legume lectin and several interesting observations regarding its unfolding have been published from our laboratory. The present thesis is an extension of the same work to enrich our knowledge about the folding behaviour of PNA. The thesis describes both experimental as well as theoretical insight on unfolding of PNA. Chapter 1 is a general discussion on lectins. Lectins are carbohydrate binding proteins of non immune source. Lectins are generally found in all type of organisms- plants, animals as well as micro-organisms. Among the plant lectins “legume lectin” is a very well studied system. Legume lectins share a general tertiary structural fold; “jelly roll fold” while they vary in their quaternary structure. Thus they can be considered as “natural mutants” in the context of quaternary structure. The origin of the lectins, structure and sugar specificity have been discussed with emphasis on legume lectin family. Chapter 2 describes the thermodynamics related to the urea induced denaturation of PNA. PNA shows a very interesting unfolding profile, populating one molten globule like intermediate during thermal as well as chaotrope induced denaturation. The molten globule like intermediate loses most of its tertiary structure but retains sufficient secondary structure. Surprisingly, the molten globule like state retains its carbohydrate binding specificity like the native PNA. A model has been developed to fit the chaotrope induced three state denaturation profile of PNA. The model considers the tetramer to dissociate to monomeric intermediate, which in turn dissociates to complete denatured state. All the relevant thermodynamic parameters (∆G, ∆Cp, Tg) associated in the denaturation process have been extracted. The tetramer is found to be ~30 kcal/Mole more stable compared to the intermediate and the intermediate is ~8 kcal/Mole more stable compared to the denatured. The denaturation process has been followed by the changes in hydrodynamic radii by dynamic light scattering (DLS). The profile of change in hydrodynamic radius and the % intensity clearly identify the generation of two species simultaneously. The analysis shows that the intermediate is ~40 % unfolded in nature. Thus this chapter deals with the detailed study of thermodynamics and dynamic light scattering study of the urea induced denaturation of PNA. Chapter 3 deals with the effect of 2, 2, 2 - trifluoroethanol (TFE) on the structure of PNA at two different pH. TFE is a well known co-solvent and is widely used to induce α- helical structure in a protein. The secondary structures induced by TFE are assumed to reflect conformations that prevail during early stages of protein folding. Thus it was quite interesting to notice the structural changes induced by TFE. The effect of TFE has been studied at two different pH- neutral pH of 7.4 and acidic pH 2.5. The  structure of the protein is accentuated in the presence of TFE at low concentration at both the pH. TFE induces α-helical structure from 40 % (v/v) concentration onwards at both the pH. TFE at 15 % concentration induces a molten globule like structure at low pH. The quenching of acrylamide suggests that the protein at low pH and 15 % TFE concentration has a more compact structure compared to the protein at low pH in absence of TFE as well as 6M guanidine hydrochloride (GdnHCl). Further studies of hydrodynamic radii by dynamic light scattering (DLS) also reveal that the protein undergoes some kind of compaction in presence of 15 % TFE at low pH. The induction of this type of molten globule like state at neutral pH has not been observed. Chapter 4 describes the molecular dynamics simulation of deoligomerization of PNA. The native PNA (PDB code 2PEL), excluding any ligand and metal ions has been simulated at 300 K, 400 K, 500 K and 600 K for 500 ps. The overall destabilisation has been followed by root mean square deviation (RMSD), the radius of gyration (Rg) and the solvent accessible surface area (ASA), while the atomistic details are revealed by residue wise RMSD (RRMS), hydrogen bonds and cluster analysis. The protein shows a quite a dramatic change in RMSD and radius of gyration profile at 600 K. RRMS shows that the residues belonging to the loops, mainly in the metal binding site show quite high flexibility. The relative change in average accessible surface area reveals that the primary core of the protein is exposed at 600 K while it is well buried till 500 K. The hydrogen bond analysis clearly shows that with increase in temperature number of hydrogen bonds starts decreasing. Mainly the hydrogen bonds involving side chain interactions are broken. Surprisingly, not all the monomers behave similarly. Monomers C and D are more perturbed compared to monomers A and B. The asymmetry in the interfaces of the monomers may be the key reason for it. The change in the interfaces has been probed by hydrogen bond analysis and cluster analysis. The GSIV type interfaces (A-D and B-C) have been found out to be the most dynamic in nature compared to the other two interfaces. Thus, this chapter reveals the early stage of unfolding of PNA, where perturbation in secondary and tertiary structural level is quite prominent but the interfaces are still holding weakly and are not completely dissociated. Chapter 5 is the continuation of the molecular dynamics simulation on unfolding of PNA, where the effect of metal ions has been illustrated. The monomeric PNA has been simulated to compare its dynamics with the tetramer. The metal binding loop (125-135) becomes unstable and opens up for the monomer even at 300 K after 800 ps. The monomer at 600 K is completely disorganized. The instability of the metal binding loop of the monomer triggers the urge to study the simulation in presence of metal ions (Ca2+ and Mn2+). The monomer bound with metal ions shows steady fluctuation at 300 K. Binding of metal ions seems to bring stability even at 600 K. Surprisingly binding of metal ions to the metal binding site not only stabilises the metal binding loop but also stabilises residues at back beta sheet which are involved in oligomerization. Hence, another simulation of the tetramer at 600 K bound with metal ions has been done. It has been shown that binding of metal ions increases the stability of the protein without altering the denaturation pathway. Appendix A describes a completely different study from PNA. The initial spectral and kinetic characterization of 7, 8- Diaminopelargonic acid Synthase (DAPA Synthase) has been done from Mycobacterium tuberculosis. The DAPA Synthase gene has been cloned earlier in our laboratory and the same has been used for further studies. This is a well known pyridoxal-5′ phosphate (PLP) dependent enzyme, which converts 8- Amino-7-oxopelargonic Acid (KAPA) to 7, 8-Diaminopelargonic Acid (DAPA) in the second step of biotin biosynthesis. DAPA Synthase uses S-adenosylmethionine (SAM) and KAPA as substrate. The first half of the enzymatic reaction has been followed spectroscopically, both by steady state and stopped flow. The enzyme seems to undergo change in conformation as evident from fluorescence and circular dichroism study. The Km value has been determined using bioassay technique. The detailed characterization of the enzyme has been described in this chapter.

Resumo: A presente pesquisa objetivou avaliar o efeito da redução do espaçamento entrelinhas sobre os períodos de interferência e a produtividade do amendoim rasteiro (Arachis hypogaea cv. Runner IAC 886). O experimento foi instalado no município de Jaboticabal, SP, em um Latossolo Vermelho de textura média. Os tratamentos constaram de dois espaçamentos entrelinhas de semeadura (80 e 90 cm), divididos em dois grupos. No primeiro as plantas daninhas foram controladas desde a emergência até os 0 (inteiramente no mato), 30, 45, 60, 82, 97 e 112 dias. Após estes períodos, as plantas daninhas que germinaram foram deixadas crescer livremente. No segundo, as plantas daninhas conviveram com a cultura pelos mesmos períodos do grupo anterior, sendo que após cada período foram removidas das parcelas. O delineamento experimental foi o de parcelas subdivididas, nas quais se constituíram por parcelas os diferentes espaçamentos e por subparcelas os períodos, totalizando 28 tratamentos em quatro repetições. As principais plantas daninhas presentes na área foram Digitaria sp., Xanthium strumarium, Acanthospermum hispidum e Cenchrus echinatus. Para uma perda tolerável de 5% de produtividade, o período crítico de prevenção da interferência foi dos 27 aos 76 e dos 35 aos 96 dias após a emergência para os espaçamentos de 80 e 90 cm, respectivamente, sendo que a queda de produtividade das parcelas mantidas no mato em relação às no limpo foi de mais de 80%, independentemente do espaçamento. / Abstract: The research was conducted to evaluate the effect of reduced row spacing on the extension of interfeence periods on peanut yield (Arachis hypogaea cv. IAC Runner 886). The experiment was conducterd in Jaboticabal, SP, Brazil, on a Red- Latosol of medium texture. The treatments consisted of two row spacing (80 and 90 cm), divided in two groups. At the first one, the weeds were controlled since the emergence until 0 (kept with the weeds), 30, 45, 60, 82, 97 and 112 days after the peanut emergence. After those periods, the weed emerged and grew without control. At the second group, the weed grew since the peanut emergence during the same periods from the first group, however, at each period the weeds were removed from the plots. The experimental design was the split-plot scheme, being the main plots constituted by different row spacing and subplots constituted by periods of weedy or weed control, in a whole of 28 treatments with four replicates. The main weed at the area where: Digitaria sp., Xanthium strumarium, Acanthospermum hispidum and Cenchrus echinatus. To an acceptable yield loss of 5%, the critical period of interference control was from 27 to 76 and from 35 to 96 days after the emergence at the spacing rows of 80 and 90 cm, respectively, but the yield reduction at the non-controlled weed plots related to the plots free from interference was more than 90%, independent of the row spacing. / Orientador: Pedro Luis da Costa Aguiar Alves / Coorientador: Maria do Carmo Morelli Damasceno Pavani / Banca: Robinson Antonio Pitelli / Banca: Ricardo Victoria Filho / Mestre

Peanut allergy is a public health concern which affects a significant proportion of the population. Accidental exposure to peanut can cause severe and fatal reactions in peanut allergic individuals and currently their only safeguard is to practise careful avoidance. Identification and protection of at-risk members of the allergic population is critical in managing this life-threatening condition. This thesis produces key data to enable this. A prospective study was performed on 60 peanut allergic participants to determine thresholds of reactivity to peanut using oral challenges with incrementally increasing amounts of peanut protein. Following a double-blind placebo-controlled peanut challenge, participants received three further peanut challenges, two with co-factors: sleep deprivation and exercise, and one without. Severity was measured using a numerical scale derived from symptoms and serum tryptase was measured at each challenge. A total of 187 challenges were performed. Findings were that the median amount of peanut protein which induces a reaction in 10% of the population (ED10) was 12.3mg (95% CI 7.3,20.4) equivalently this suggests that 90% of the allergic population will not react to doses below this level. Both sleep deprivation and exercise have a significant effect on lowering reaction threshold (ED10), by 5 times and 2.5 times respectively. Separately there is a reduction in threshold with successive challenges. Co-factors also significantly increased symptom severity during challenge reactions. In particular sleep deprivation significantly increased the severity of gastrointestinal symptoms suggesting that a stressful stimulus may affect intestinal permeability. Evidence was provided for the importance of asthma as a risk factor which increased the severity of respiratory symptoms during reaction. Using a novel visual analogue scale for measuring the participant’s perception of severity, a poor correlation was observed between the participant’s perception of the reaction and the overall numerical severity score, suggesting that participants misperceive severe symptoms. This thesis provides the first data showing that symptom patterns in repeated challenges show a high degree of homogeneity within individuals, but importantly that this symptom homogeneity is also observed across individuals. Lastly the utility of serum tryptase in identifying food allergic reactions has been disputed previously. This thesis provides evidence of its value and identifies a rise cut-off of 30% as being diagnostic of a food allergic reaction, but cautions that acute levels must be compared with baseline as this rise may occur within the normal range.