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Martin-Luther-Universität Halle-Wittenberg (2013)

Understanding terminal drought tolerance in barley using AB-QTL analysis and an integrated omics approach

Kalladan, Rajesh

Titre : Understanding terminal drought tolerance in barley using AB-QTL analysis and an integrated omics approach

Auteur : Kalladan, Rajesh

Université de soutenance : Martin-Luther-Universität Halle-Wittenberg

Grade : Doctor of Philosophy (PhD) 2013

Résumé
Terminal drought is one of the major constraints for barley production that affects both seed yield and quality. The major objective of this investigation was to understand the mechanism of terminal drought tolerance for seed yield and quality using two complementary approaches. Firstly, an advanced backcross quantitative trait locus (QTL) analysis was carried out to identify exotic regions influencing terminal drought tolerance using a BC3-DH population developed between the cultivated parent Brenda and the wild accession, HS584. Secondly, an integrated omics (transcripts and metabolites) together with various physiological parameters were used o characterize the significance of staygreen/senescence mechanisms under terminal drought using contrasting elite breeding lines exhibiting staygreen and senescence phenotypes. Terminal drought was imposed by either spraying with potassium iodide or withholding water at 10 days after flowering. Significant contribution of various QTL for yield and seed quality parameters by HS584 indicated that wild barley is a potential source of terminal drought tolerance in various breeding programmes. With respect to second approach, our study reinforces that senescence induced remobilization of stem reserves is an important component of seed filling under terminal drought. LP104, characterized by senescence phenotype performed better compared to staygreen in terms of both seed yield and quality under terminal drought. In spite of higher stem water soluble sugars (WSC) in the staygreen genotype, its poor performance with respect to stem remobilization compared to senescing (LP104) indicates that stem weight/WSC at anthesis alone cannot be considered as a secondary parameter to screen for terminal drought tolerance in barley. The poor performance of one of the senescing genotypes, LP110 compared to LP104 with respect to leaf nitrogen remobilization also hints to the fact that senescence alone may not be sufficient for remobilization of stored reserves, which is to be explored in great detail.

Mots clés : AB-QTL ; barley ; stem remobilization ; seed quality ; yield ; staygreen ; senescing ; terminal drought ; wild relatives

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Page publiée le 24 juin 2013, mise à jour le 7 janvier 2019