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Northwest University of Science and Technology (2013)

Assessment of Drought Tolerance of Triticum L. Species and Analysis of the Drought Responsive Proteins in Triticum boeoticum

Muhammad Abdul Rab Faisal Sultan

Titre : Assessment of Drought Tolerance of Triticum L. Species and Analysis of the Drought Responsive Proteins in Triticum boeoticum

Auteur : Muhammad Abdul Rab Faisal Sultan

Grade : Doctoral Dissertation 2013

Université : Northwest University of Science and Technology

Résumé
Wheat (Triticum aestivum L.) is the second most commonly used staple food, grown invarious parts of the world under diverse climatic conditions. Wheat like other crops is avictim of many environmental stresses, among them drought is the major abiotic constraintaffecting the growth, yield and quality of wheat. Drought is a worldwide problem,constraining crop production seriously and recent global climate change has made thissituation more serious. It is prerequisite to develop drought tolerant wheat varieties forsurvival in water deprived areas of world. Wild wheat relatives serve as rich source of genesconferring tolerance against environmental stresses. The integration of molecular techniqueswith physiology and plant breeding is a new approach being used to improve theenvironmental adaptation and yield of field crops. Two-dimension electrophoresis (2-DE),combined with protein identification by Matrix-assisted laser desorption/ionization-Time ofFlight (MALDI-TOF), has often been employed to identify individual protein of interest.Assessment of leaf low abundant proteins is hindered due to large quantity of Rubisco withinplant leaf tissues. An efficient protein extraction method is a prerequisite for proteomicanalysis. In present study, initially drought stress tolerance was assessed in two groups ofwheat separately via three physiological indices, i.e. Relative water content (RWC),Malondialdehyde (MDA), and Proline content (PC), using two well-known old cultivars(Shaanhe6&Zhengying1) with strong drought resistance and sensitiveness respectively asreferences. First group included five wheat species of Triticum L. i.e., T. boeoticum (2n=14,AbAb), T. dicoccum (2n=28, AuAuBB), T. araraticum (2n=28, AbAbGG), two cultivatedcultivars of T. durum (AuAuBB), whereas second group contained five elite winter wheat(Triticum aestium) cultivars including Xiaoyan22, Shaan354, Changwu134, Chang4640,Xinong928. Water stress condition was induced by treating the roots of wheat seedlings withHoagland’s solution containing20%polyethylene glycol6000(PEG-6000), at3leaf stage.However, the control group was supplied with normal Hoagland’s solution under the samegrowth conditions as the stressed treated plants. Then, two protein preparation protocols ofwheat leaf proteins used for2-DE analysis, a conventional trichloroacetic acid (TCA)/acetonemethod (named as conTCA/ac.) and an improved TCA/acetone protocol which is firstdeveloped in this study by combining phytate/Ca2+fractionation with TCA/acetoneprecipitation (designated as imTCA/ac.), were compared to reveal major differences in the2- DE images of wheat leaf proteins obtained from the two protocols in current study and todevelop a rapid, inexpensive and efficient protein preparation protocol to separate low-abundance proteins in wheat leaf tissues by2-DE analysis. Finally, water-stress responsiveproteins in wild wheat species (T. boeticum) were analyzed by2-DE. The main purposes ofthis study are ; to select drought tolerance wild wheat species and common wheat cultivars, todevelop a rapid, inexpensive and efficient protein preparation protocol for separation of low-abundance proteins in wheat leaf tissues by2-DE analysis, and to identify water-stressresponsive proteins in drought tolerant wheat. The main results of this study are as follows:1. The experimental data of the five wild wheat species showed that YS-1L (T. boeoticum)was most drought tolerant among studied species having significantly higher PC and RWCwhile lower MDA content, under water stress condition. The order of water stress tolerance ofthese species according to the three parameters is : YS-1L>YS-2L>SH6>87341>ZY1>MXLK>ALLT.2. The data of the five elite winter wheat cultivars showed that Changwu134and Xinong928had least reduction in leaf RWC, least increase in leaf MDA content and largest amount of PCaccumulation under48or72h of water stress. While Xiaoyan22exhibited greatest reductionin leaf RWC, largest increase in leaf MDA content and lowest amount of PC accumulation.The RWC and MDA content of Changwu134and Xinong928of stress treated group reachedto the level of the control when stress was dismissed for24h, while those of Xiaoyan22didnot. Combining the three physiological parameters, the rank of water stress tolerance of thesecultivars is : Xinong928>Shaanhe6>Changwu134>Chang4640>Zhengyin1>Shaan354>Xiaoyan22. Xinong928is most drought resistant cultivar among the newly released wheatcultivars, compared with the well-known drought resistant and sensitive reference cultivarsi.e., Shaanhe6and Zhengyin1respectively

Mots clés : Triticum L. Species; Triticum boeoticum; Drought tolerance; RWC; MDA; PC; Leaf proteome; Drought responsive proteins;

Présentation (CNKI)

Page publiée le 6 avril 2014, mise à jour le 29 septembre 2017