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Chinese Academy of Agricultural Sciences (2008)

Studies on the Relationships between Amino Acids Metabolism and Drought-resistance of Winter Wheat

Xu Chun Ying

Titre : Studies on the Relationships between Amino Acids Metabolism and Drought-resistance of Winter Wheat

Auteur : Xu Chun Ying

Grade : Doctoral Dissertation 2008

Université : Chinese Academy of Agricultural Sciences

Résumé
The relationships between drought-resistance and amino acids metabolism in wheat were studied for exploring whether amino acids metabolism can be an indicator to evaluate the drought-resistance of wheat, different drought-resistant winter wheat varieties were selected based on their carbon isotope discrimination and actual drought information at first. These varieties were planted in pots, and the soil moisture was controlled under the condition of 85% in the jointing stage, the 15N-labelled fertilizer was applied in the stage. The dynamics of amino acids nitrogen isotope composition of leaves is analyzed by GC-MS and GC-C-IRMS for these varieties. The dynamics and difference of amino acids metabolism are also investigated among the different wheat varieties according to the dynamics change of amino acids nitrogen isotope composition. Finally, the change of carbon isotope composition was compared between control varieties and treated varieties by application of 15N-labelled fertilizer.The following conclusions are drawn :(1) The different genotypes of winter wheat grain have different carbon stable isotope discriminations (△‰), which are generally fallen in the range of 18‰to 21‰. Furthermore, there is a very significant difference of△‰between strong and weak drought-resistant wheat varieties in this research.(2) The dynamics of nitrogen assimilation and amino acids metabolism are studied for different wheat varieties which grew in the conditions of soil moisture content 85% during the jointing stage. The results are as following : From the whole time of 10min-24h after the application of 15N-labelled fertilizer, the strong drought-resistant varieties have very significantly higher nitrogen assimilation efficiency and nitrogen uptake efficiency than weak and middling drought-resistant varieties wheat, while there are no distinct difference between weak and middle drought-resistant varieties in this research, however, there are still difference between the three strong varieties for nitrogen uptake efficiency.δ15N of amino acids shows linear accumulation in the strong and middle drought-resistant varieties in the 24 hours, and the strong varieties increase more quickly and fast, whileδ15N of amino acids almost keep stable during 3h-24h for the weak drought-resistant varieties, which is the most difference among them. No significant change is observed on the content of protein amino acid, although which is changeable either increased or decreased. The increase ofδ15N is significantly bigger in the strong drought-resistant wheat varieties such as Bainong9310, Linfen50744, W98zhong18 than in the middle or weak drought-resistant wheat varieties, including Glu/Gln, Asp/Asn, Ser, Gly, and it is bigger too in the middle drought-resistant varieties than weak drought-resistant varieties after 15NH4+ treatment within 24h. On the other hand, those amino acids which synthesize relatively slow or late including Val, Leu, Ile, Met, Pro, Phe,Tyr etc, change more greatly in the strong drought-resistant varieties than middle and weak drought-resistant varieties.Based on our results, we can make a conclusion that there is significant difference of amino acids metabolism between strong drought, middle and weak resistant wheat varieties in the jointing stage under the 85% soil moisture condition. Therefore, the dynamics of amino acids metabolism can be used as an index to identify the drought character of winter wheat in the jointing stage, which could play a great theoretical and practical role for selecting drought-resistant wheat varieties.

Mots clés : winter wheat drought-resistance amino acids stable isotope

Présentation (Dissertationtopic)

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