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Wageningen University (2014)

Molecular and genetic analysis of drought tolerance in potato

Sultana, Nasrin

Titre : Molecular and genetic analysis of drought tolerance in potato

Auteur : Sultana, Nasrin

Université de soutenance : Wageningen University

Grade : Master of Science (MS) 2014

Résumé
Potato is the most important non-cereal food crop in the world and it is detrimentally affected by drought stress. Researches related to drought tolerance have an escalating importance with a view to combating hunger. Drought tolerance traits are quantitative and genetic variation is known to exist for these. The response of plant is undoubtedly regulated at the molecular level and studying the genes involved is an important route to gain insight. In addition, QTL identification has been proven to have enormous potential for target oriented trait improvement. Keeping this view in mind, a study was performed for the gene expression of C-partitioning genes, drought tolerance genes and recombinants identification targeted to dissect QTL loci for drought tolerance. The C-partitioning genes Stin8, stin6 and Sus3 have been taken into account as their activities signify the capability of potato plant to adapt assimilate partitioning when subjected to drought. The drought responsive genes TAS14, ER24 and NF-YC4 had been studied to unravel the regulation of the response when drought stress is embarked upon. An e-QTL hotspot for drought response and a QTL locus colocalizing with maturity locus CDF had been identified earlier in close proximity to each other, on chromosome 5. Much still needs to be understood on their distinct effects on plant drought response. Two leaf types i.e. source and sink of 8 genotypes from a previously conducted mild drought stress greenhouse experiment for two different time points of stress. In case of C-partitioning genes, for overall comparison through all genotypes, the invertases Stin8 and Stin6 exhibited contrasting expression with respect to timepoint. Moreover, Stin8 and Sus3 showed contrasting expression in case of leaf type for the same timepoint. Albion was an remarkable genotype, giving a unique peak for its melting curve pattern compared the other genotypes only for Stin8 and Stin6. The reason for this is still unclear. The genotype Mondial, known for its shutting down of tuberization under stress, exhibited downregulation for the genes. The drought tolerance genes comply with the findings of previous works i.e. up-regulation for TAS14 and ER24 under stress, and downregulation for NF-YC4. The genotype Albion again was exceptional as it was found to be sensitive to drought but give upregulation for TAS13 and ER24 and downregulation for NF-YC4. Genotype Eos, known to be drought tolerant, showed significant downregulation of NF-YC4 and upregulation of gene ER24. In case of recombinant screening, 49 plants in total were obtained as recombinant among which 4 lines were recombinant for between Zinc Finger Domain marker and Seryl-tRNA synthetase marker i.e. between left flank of both of the maturity locus and eQTL hotspot ; 1 line was for Zinc Finger Domain marker and TERF1 marker i.e. inside maturity locus ; 39 lines were recombinant for between SeryltRNA synthetase marker and Peroxidase 27 marker i.e. inside eQTL hotspot region, 3 lines were for between TERF1 and Peroxidase 27 marker i.e. in between two right flank of maturity locus and eQTL hotspot ; 2 lines were between Zinc finger domain marker and Peroxidase 27 i.e. in between left flank end of maturity locus and right flank end of eQTL hotspot.

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Page publiée le 20 février 2016, mise à jour le 19 octobre 2018