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3 pp. / Growing degree days to reach various growth stages in small grains is presented in this publication, as well as the optimum timing of cultural practices relative to crop growth stage.

Stem rust and Yellow rust diseases are the two major wheat fungal diseases causing considerable yield losses in Turkey and all around the world. There are studies which are carried out to identify and utilize resistance sources in order to obtain resistant lines of wheat. However, virulent pathotypes are continuously being important threats to wheat production and yield. For that reason, new approaches for rapid identification are needed. The aim of this study was to investigate and to understand the structural and functional differences between the resistant and sensitive durum wheat cultivars to the plant fungal diseases of stem and yellow (stripe) rusts. To aim this, forty durum wheat recombinant inbred lines (RILs), which were previously determined to be resistant or sensitive to stem and yellow rust diseases, were investigated by the noninvasive Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy. Also, classification of the resistant and sensitive lines depending on the structural and functional differences has been attempted. The FTIR spectra for stem rust disease showed that, resistant durum wheat lines had a significant increase in the population of unsaturation in acyl chains of lipid molecules, an increase in lipid and in total protein content and also an increase in carboxylic acids and alcohols. For yellow rust disease, resistant lines had a significant increase in hydrogen bonding and they had also a more ordered membrane structure. In Principal Component Analysis for stem rust disease, according to 3700-650 cm-1 region, amide III band (1213-1273 cm-1 region) and C-H stretching region (3020- 2800 cm-1), the resistant and sensitive groups were separated successfully. For yellow rust disease, according to 3700-650 cm-1 region, Amide A and Amide III bands, the resistant and sensitive lines were grouped distinctly. FTIR spectroscopy provides a useful approach to determine the differences in molecular structure of durum wheat RILs regarding resistance of lines to fungal diseases. However, further research is still needed to ensure if the structural and functional differences in biomolecules of the samples could be used as molecular markers for discrimination of rust resistant materials from rust sensitive ones.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Le blé dur est la matière première de base pour la production de semoules et de pâtes. Les origines des rendements semouliers et qualité des pâtes sont multifactorielles. Or, il n’existe pas aujourd’hui d’outil global permettant de prédire les valeurs semoulières et pastières des blés durs sur la base des caractéristiques physiques et biochimiques des grains. Le travail mené dans le cadre de cette thèse s’attache à objectiver le potentiel semoulier et pastier de lots de grains, issus de pratiques culturales innovantes, dans une optique d’améliorer la durabilité de la filière blé dur.Des lots de grains de blé dur ont été caractérisés et leurs variabilités mises en relation avec les différents itinéraires techniques agricoles dont ils sont issus. L’impact de la qualité des récoltes sur le comportement à la mouture des lots, ainsi que sur l’aspect des pâtes sèches et la texture des pâtes cuites a été étudié. Les teneurs en protéines, en cendres et la granulométrie de la semoule ont été identifiées comme des facteurs influençant la qualité des pâtes. Une démarche « plan d’expériences » a été développée pour évaluer l’impact d’un seul facteur, indépendamment des deux autres, sur la qualité des pâtes. L’efficience des procédés de transformation en fonction de la variabilité de la matière première a également été appréciée. En particulier, l’impact des caractéristiques des grains de blé dur sur les énergies nécessaires à la mouture, les liens entre composition de la semoule et comportement à l’extrusion et l’efficacité de différents diagrammes de séchage sur la qualité des pâtes en fonction de leurs compositions, ont été analysés. Une étude a été également menée sur l’état de polymérisation des protéines au cours de la fabrication des pâtes. Enfin, cette thèse a permis la constitution d’une base de données qui contribuera à la prédiction de la qualité des semoules et pâtes en fonctions des caractéristiques physiques et biochimiques des blés durs. / Durum wheat is the best raw material to process semolina and pasta. The origins of high semolina yield and the good pasta quality are multifactorial. However, there is currently no tool predicting milling and pasta making results based on physical and biochemical characteristics of durum wheat grains. The work carried out in this PhD thesis attempts to objectify the technological value of durum wheat samples, grown with innovative technical practices in order to improve sustainability of the French durum wheat chain.Durum wheat samples batches were characterised and their variability was related to the different agricultural technical routes used. The impact of the grain quality on the milling behaviour of the samples, as well as the appearance of the dry pasta and the texture of the cooked pasta was studied. Protein, ash contents and semolina particle size distribution were identified as factors influencing pasta quality. An “experimental design” approach was developed to obtain a non-distorted estimate of how each variable impacts the quality of pasta, independently of the other two variables. Efficiency of the semolina milling and pasta making processes depending on the variability of the raw material was also assessed. Especially, the impact of durum wheat grains characteristics on the energies required for milling, the relationship between semolina composition and extrusion behaviour and the effectiveness of different drying diagrams on the quality of the pasta based on their compositions were analysed. A study on the protein polymerisation state during the pasta making process was also conducted. Finally, this PhD thesis has contributed to the development of a database that will predict semolina and pasta quality depending on physical and biochemical characteristics of durum wheat.

Tan spot, caused by Pyrenophora tritici-repentis (Ptr), is a major foliar disease on wheat. The pathosystem involves three pairs of necrotrophic effector (NE) and host sensitivity (S) gene interactions, namely Ptr ToxA-Tsn1, Ptr ToxB-Tsc2 and Ptr ToxC-Tsc1. Additionally, genetic factors conferring race-nonspecific resistance have been identified. The objectives of this study were to map tan spot resistance QTL and investigate the role of NE-S interactions in disease in durum using association and bi-parental mapping. Evaluation of a worldwide collection of durum accessions allowed identifying highly resistant nineteen lines to multiple Ptr races. Association mapping revealed genomic regions on chromosomes 1A, 2B and 3B significantly associated with resistance to tan spot, which likely correspond to Tsc1, Tsc2 and racenonspecific resistance. Using a bi-parental population derived from Ben and PI 41025, we found that ToxA-Tsn1 interaction plays no significant role in disease, instead a major race-nonspecific QTL on chromosome 5A was identified.

Le blé dur, du fait de sa vitrosité et de sa richesse en protéines est particulièrement adapté àla fabrication des pâtes alimentaires. Cette céréale, largement cultivée dans le bassinméditerranéen, est fréquemment soumise à des stress hydriques et thermiques. Les objectifsde cette thèse ont été d'approfondir les connaissances sur les modalités d'accumulation etd'assemblage des protéines de réserve au cours du développement du grain. Un suivi fin duremplissage du grain, de la morphologie des corps protéiques, des changements d'état redox etde la distribution en taille des polymères de gluténines a été réalisé. L'influence, sur cesdifférents paramètres, de températures élevées appliquées à différents stades dedéveloppement du grain a été étudiée.En privilégiant l'accumulation des protéines au détriment de l'amidon, le stress thermiquejoue un rôle non négligeable dans l'obtention de grains vitreux et à fortes teneurs en protéines.L'arrêt de la croissance du grain, observé à 45% de teneur en eau, est précédé de la mise enplace de la matrice protéique. L'accumulation de la matière sèche apparaît étroitement liée à ladynamique de l'eau, confirmant le lien entre teneur en eau et poids final du grain. Au cours duremplissage du grain, les températures élevées exercent un effet significatif sur la formationdes polymères de gluténines insolubles dans le SDS. Leur formation n'intervient qu'en fin dedessiccation et en deçà de 30% de teneur en eau. La durée de cette phase ultime d'oxydation etd'assemblage des polymères de gluténines a été reliée à la teneur en protéines.L'évolution du statut redox du grain montre qu'une accumulation massive de polymères degluténines intervient juste avant l'entrée en dessiccation du grain qui coïncide avecl'effondrement de l'ascorbate dans le grain. Coïncidant avec cette oxydation manifeste, unphénomène de glutathionylation des protéines a été détecté avec une rupture de l'activité de laCAT. Au cours de la dessiccation, les activités de la SOD et de la GR augmentent de façonsignificative. Cette synthèse tardive pourrait se produire au niveau de la couche à aleurone etdu germe en réponse à l'oxydation massive de l'albumen.Enfin, nous avons analysé le couplage entre oxydation des thiols protéiques et croissance entaille des polymères de gluténines. Très précocement, les sous-unités de gluténiness'assemblent sous forme d'oligomères partiellement réduits. Durant le remplissage du grain,une oxydation massive des thiols intervient avec la formation de polymères majoritairementcomposés de SG-HPM sur lesquels viendraient se fixer les SG-FPM. Au cours de la dessiccation,la taille des polymères augmente. Les structures polymériques formées au cours del'élaboration du grain possèdent un nombre de cystéines réduites élevé et incompatible avecun modèle d'assemblage linéaire. Les résultats obtenus nous permettent de proposer unrepliement tardif des SG-FPM, postérieur à leur insertion dans les assemblages oligomériques.Ils nous amènent à mettre en avant le rôle du glutathion comme co-facteur de la genèse despolymères, à l'opposé des thèses classiques qui en font plutôt un inhibiteur de la croissance entaille des polymères de gluténines. / Durum wheat is particularly recognized as the most suitable raw material for pasta makingdue to its vitreousness and its high protein content. This cereal is commonly grown inMediterranean environment and then frequently submitted to high temperature and waterstress. The aim of this thesis was to better understand the accumulation and assembly ofstorage proteins during the grain development. Evaluation of the grain filling, the morphologyof protein bodies, the redox status and the size distribution of glutenin polymers were carriedout. The effect of high temperatures applied at different stages of the grain development onthese parameters was studied.By favouring protein accumulation at the expense of starch, heat stress appeared essentialto obtain vitreous grains and high protein content. The arrest of grain growth observed at 45%grain water content is preceded by the formation of a continuous protein matrix. The dry massaccumulation is closely related to water dynamics, confirming the link between water contentand final grain weight. During grain filling, high temperatures have a significant effect on theformation of SDS-insoluble glutenin polymers. It occurred when grain water concentrationdropped below 30%. The duration of this final stage of oxidation and assembly of gluteninpolymers was related to protein content.Changes in the grain redox status showed an accumulation of glutenin polymers mainlyoccurring before the onset of grain desiccation phase and coinciding with the ascorbateoxidation. This clear oxidation coincided also with the glutathionylation of proteins and thedrop of the CAT activity. During desiccation, the activities of SOD and GR increased significantly.This late synthesis could occur in the aleurone layer and germ in response to massive oxidationof the endosperm cells.Finally, we evaluated the coupling between protein thiol oxidation and size increase ofglutenin polymers. In the early stages, glutenin subunits assembled as oligomers partiallyreduced. During grain filling, a strong thiol oxidation took place with the formation of polymersmainly composed of HMW-GS associated with LMW-GS branching. The polymer size increasedduring desiccation. The polymeric structures obtained during the grain development presenteda high number of reduced cysteines inconsistent with a linear concatenation model ofassembly. It allowed us to propose that the folding of LMW-GS is a late event, subsequent totheir insertion into oligomeric assemblies. These results highlighted the role of glutathione asco-factor in the polymers formation, contrasting with the common assumption that considers itas an inhibitor of the size increase of glutenin polymers.

Au cours du stockage et sous de mauvaises conditions de conservation, les grains de blé peuvent subir diverses altérations causées par le développement fongique. Les moisissures peuvent produire des toxines pouvant avoir un impact sur la santé du consommateur. L’évaluation de la diversité fongique sur blé de stockage produit localement dans les régions céréalières du Nord de la Tunisie durant deux années successives (2010-2011 et 2011-2012) a montré une dominance du genre Alternaria. L’étude de la cinétique d’évolution de cette mycoflore au cours du stockage s’est caractérisée par un profil particulier dépendant des paramètres géographiques et temporels et des conditions écophysiologiques. L’évaluation du pouvoir toxinogène a révélé un faible pourcentage d’isolats ochratoxinogènes. L’évaluation de la présence de l’OTA dans le blé ont montré des taux de contaminations largement inférieurs aux normes européennes. L’étude sur la physiologie de sporulation et la production d’OTA en Fermentation en Milieu Solide par A. carbonarius à montré une amplification de la production des conidiospores et de l’OTA par aération humide forcée. L’évaluation de l'activité antifongique de 15 bactéries lactiques isolées du blé de stockage à l’égard de 8 moisissures post-récolte a montré une bonne aptitude de Lb. plantarum à inhiber la croissance de ces moisissures. L’étude du pouvoir anti-ochratoxinogène de Lb. plantarum LabN10, Lb. graminis LabN11 and P. Pentosaceus LabN12 ont montré un effet significatif de la température, du pH et de la biomasse bactérienne sur l’inhibition de la biomasse fongique ainsi que sur la réduction d’OTA. / During storage and under bad storage conditions, wheat grains can undergo various alterations caused by fungal growth. Molds can produce toxins that can have an impact on consumer health. Assessment of fungal diversity on wheat storage locally produced cereal in northern Tunisia during two successive years (2010-2011 and 2011-2012) showed a dominance of the genus Alternaria. Study of kinetics evolution of mycoflora during storage is characterized by a particular pattern depending on geographic and temporal parameters and ecophysiological conditions. Evaluation of toxigenic fungal revealed a low percentage of ochratoxinogenic isolates. Occurence of OTA in wheat showed contamination levels under European standards. The study on sporulation physiology and production of OTA by Solid State Fermentation by A. carbonarius shown amplification and production of conidiospores OTA wet forced by aeration. The evaluation of the antifungal activity of lactic acid bacteria (LAB) isolated from the 15 wheat storage against 8 post-harvest molds showed good ability of Lb. plantarum to inhibit the growth of these fungi. The study of anti-ochratoxinogène activity Lb. LabN10 plantarum, Lb. and P. graminis LabN11 LabN12 pentosaceus showed a significant effect of temperature, pH and the bacterial biomass on the inhibition of the fungal biomass and on the reduction of OTA.

Pulses are an important component in crop rotations in the semiarid Brown soil zone of southern Saskatchewan, Canada. Besides their capability to fix nitrogen, pulse crops establish a strong symbiotic relationship with arbuscular mycorrhizal fungi (AMF), which have been shown to increase nutrient and water uptake through hyphal extensions in the soil. Incorporating strongly mycorrhizal crops in a rotation may increase inoculum levels in the soil and benefit the growth of a subsequent crop. The objective of this study was to determine if AMF potential and colonization of a durum crop is significantly affected by cropping history and to assess the impact of pulses in crop rotations on the abundance and diversity of AMF communities in the soil. In 2004 and 2005, soil, plant, and root samples were taken on Triticum turgidum L. (durum) with preceding crops of Pisum sativum L. (pea), Lens culinaris Medik (lentil), Cicer arietinum L. (chickpea), Brassica napus L. (canola) or Triticum turgidum L. (durum). Although there were few differences in soil N and P levels, previous crop had a significant effect (p<0.05) on durum yields in both years. A previous crop of pea was associated with the highest yields, while the durum monocultures were lowest. Arbuscular mycorrhizal potential and colonization were significantly affected (p<0.05) by cropping history, but not consistently as a result of inclusion of a pulse crop. Phospholipid and neutralipid fatty acids (PLFA/NLFA) were completed to analyse the relative abundance of AMF (C16:1ù5), saprophytic fungi (C18:2ù6), and bacteria in the soil. The effect of treatment on the abundance of AMF, saprotrophic fungi and bacteria were not significant (p<0.05), but the changes over time were. These results demonstrate that although previous crop may play a role in microbial community structure, it is not the only influencing factor.

Current trends in population growth suggest that global food production is unlikely to satisfy future demand under predicted climate change scenarios. Therefore, further improvements on wheat yield potential will be essential to meet future food demand. Thus, to further raise wheat grain yield it is critical to understand the physiological basis of grain number per m2 determination. Yield responsiveness to resource availability is usually related to grain number per m2 in most of grain crops, such as durum wheat. Under Mediterranean conditions, wheat yields vary widely, mainly in response to erratic rainfall, but it has been proposed that part of this variability may be reduced through nitrogen (N) management. Wheat yield responses to N fertilisation are usually related to those of grains per m2, which in turn is the consequence of processes related to floret development (floret initiation followed by floret death/survival) during stem elongation. However, there are almost no studies published relating floret primordia generation and survival in response to increases in N availabilities in wheat. Understanding the dynamics of floret primordia development as a physiological determinant of grain setting can be relevant to further increase grain yield in wheat. The focus of this thesis was to study the effects of N availability and the differences among modern cultivars (and, in some cases, combined with availability of other resources) on dynamics of floret development and survival determining the fate of these primordia and the generation of grain number in durum wheat. Six experiments were conducted (4 semi-controlled and 2 field conditions) during four consecutive growing seasons at Catalonia, NE Spain, with a combination of different N and water availabilities and contrasting modern durum wheat cultivars. Across all experiments, yield responsiveness to N was, in general, related to grain number increases as an indirect response to N through its effect on increasing growth. This is not only based on the fact that the relationship of grain number with spike dry matter was not improved if spike N were used instead, but also on the fact that detillering did increased grain number through the same relationships to spike dry matter. Also, improved spike fertility was due to both producing more fertile florets (in response to N and water or to the removal of competing shoots) and to reduce the percentage of failure of fertile florets in becoming grains. Responsiveness of the number of fertile florets was determined by a developmental response of floret primordia, which under high resource availability conditions continued developing normally in some distal florets of the spikelets, at any position of the spike, whilst in more stressful conditions their development stopped. Genotypic variation in fruiting efficiency was found for modern durum wheat cultivars and there was a tendency for some cultivars to have higher values of fruiting efficiency in most of the environments. Differences in fruiting efficiency were responsible for genotypic differences in grain number. A functional negative relationship was found between grain weight and fruiting efficiency, revealing a trade-off related to spike growth per floret developing normally.