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Wageningen University (2011)

Genetic dissection of drought tolerance in potato

Anithakumari, A.M.

Titre : Genetic dissection of drought tolerance in potato

Auteur : Anithakumari, A.M. 

Université de soutenance : Wageningen University

Grade : Doctor 2011

Présentation
Drought is the most important cause of crop and yield loss around the world. Breeding for drought tolerance is not straightforward, as drought is a complex trait. A better understanding of the expression of drought traits, the genes underlying the traits and the way these genesinteract will significantly increase the success of breeding for drought tolerance.
Potato is an important food crop, yet it is relatively susceptible to drought. As a first step towards identifying the genetic basis for drought tolerance in potato, we make use of diploid potato populations that have been genetically well characterized (CxE, SHxRH). The CxE population was extensively evaluated for drought tolerance in vitro and for two successive years (2008, 2009) under greenhouse conditions and the data were used for QTL mapping. For optimal QTL mapping, we expanded the CxE and SHxRH genetic maps with 499 SNP markers (two arrays 384 and 768SNP arrays respectively, enriched for putative stress tolerance candidate genes). The SNPs were discovered in public EST databases using QualitySNP software and detected with the Illumina GoldenGate assay. About 300 SNPs served as bridge markers between the CxE and SHxRH maps. This will enable us to make use of the extensive genetic and sequence information of the SHxRH population and the RH genome sequence. With the availability of the potato genome sequence of the doubled monoploid DM1-3 516R44 (DM) (www.potatogenome.net), it was possible to further examine the SNP marker loci for paralogs and intron spanning sequences. In total 732 SNP marker loci were found to be unique in the potato genome sequence. Many of these SNP markers not only served as landmarks on the genetic map but may also as putative genes underlying quantitative traits. In addition the validated SNP markers are now utilized asanchors in the potato physical map.
We investigated the possibility of screening potato for relevant drought traits in in vitrocultures and evaluated the CxE population for the response to PEG-induced water deficit stress and recovery potential after stress. Significant genetic variation was observed for the response to drought and for recovery potential. Several shoot and root growth traits were measured. In this study the genetic variation and heritability estimates were high to very high for the measured traits under control and recovery condition. In total 23 QTLs were detected in plants under control, stress and recovery treatments. Interesting putative candidate genesthat may underly stress response QTLs were identified.
The drought tolerance evaluation of the CxE population in pots in the greenhouse included traits like leaf Relative Water Content, δ13C as a measure of Water Use Efficiency, Chlorophyll Fluorescence, Chlorophyll Content, shoot and root biomass and tuber yield. The progeny displayed a wide contrast for drought tolerance, with individuals surviving and recovering completely after 3 weeks of drought, and others completely wilted beyond recovery. Most of the traits had high heritabilities. QTLs effective in multiple treatments and years were detected for tuber number, tuber weight, plant height, shoot fresh and dry weight. Other QTLs were found to be dependent on the environment : QTL x Environment interaction was found for leaf d13C under drought conditions and we speculate that the function of δ13C was genetically split into a stomatal and non-stomatal component.

Mots clés : solanum tuberosum / potatoes / drought resistance / genetic analysis / diploidy / single nucleotide polymorphism / genetic markers / quantitative traits / quantitative trait loci / genetic mapping / plant breeding

Présentation

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Page publiée le 21 janvier 2015, mise à jour le 14 décembre 2021