Genome-Wide Approach to Identify Quantitative Trait Loci for Drought Tolerance in Tetraploid Potato (Solanum tuberosum L.).

Christina Schumacher,Manuela Haas,Karin Köhl,Sylvia Seddig,Ellen Zuther,Florian Schilling,Rolf Peters,Dirk Walther,Heike Sprenger,Dirk Karl Hincha,Susanne Thümecke,Renate Horn,Joachim Kopka

doi:10.3390/ijms22116123

Abstract

Drought represents a major abiotic stress factor negatively affecting growth, yield and tuber quality of potatoes. Quantitative trait locus (QTL) analyses were performed in cultivated potatoes for drought tolerance index DRYM (deviation of relative starch yield from the experimental median), tuber starch content, tuber starch yield, tuber fresh weight, selected transcripts and metabolites under control and drought stress conditions. Eight genomic regions of major interest for drought tolerance were identified, three representing standalone DRYM QTL. Candidate genes, e.g., from signaling pathways for ethylene, abscisic acid and brassinosteroids, and genes encoding cell wall remodeling enzymes were identified within DRYM QTL. Co-localizations of DRYM QTL and QTL for tuber starch content, tuber starch yield and tuber fresh weight with underlying genes of the carbohydrate metabolism were observed. Overlaps of DRYM QTL with metabolite QTL for ribitol or galactinol may indicate trade-offs between starch and compatible solute biosynthesis. Expression QTL confirmed the drought stress relevance of selected transcripts by overlaps with DRYM QTL. Bulked segregant analyses combined with next-generation sequencing (BSAseq) were used to identify mutations in genes under the DRYM QTL on linkage group 3. Future analyses of identified genes for drought tolerance will give a better insight into drought tolerance in potatoes.

Highlights

Facing global climate change and increasing demands for food production, the improvement of crop yields under limited water supply conditions and other abiotic stresses such as heat or salinity is vital for mankind [1,2,3,4]
By focusing on genomic regions relevant for drought stress, we identified a number of potential candidate genes for drought tolerance within these regions that can be further analyzed to eventually help to discriminate between drought-tolerant and -sensitive cultivars in potato breeding programs
SSR-markers derived from candidate genes for drought tolerance [34] and the information of the annotated potato genome sequence, we identified candidate genes for drought tolerance underlying DRYM quantitative trait loci (QTL) that are interesting for future studies of drought response mechanisms in potatoes and that partly overlap with previously identified transcript candidate genes for drought tolerance prediction [14]

Summary

Introduction

Facing global climate change and increasing demands for food production, the improvement of crop yields under limited water supply conditions and other abiotic stresses such as heat or salinity is vital for mankind [1,2,3,4]. As increased irrigation is expensive and ecologically detrimental, improving the plant’s own mechanisms to cope with abiotic and biotic stresses is a favorable approach [5]. Recent “omics” approaches to study drought stress response in potatoes have been performed on transcript and metabolite levels [10,11,12,13,14], transcription factors [15] and heat shock proteins [16]. Mapping of quantitative trait loci (QTL) to identify genomic regions associated with drought [17,18], foliar symptoms caused by potato virus

Methods

Discussion

Conclusion