Mapping of quantitative trait locus (QTLs) that contribute to germination and early seedling drought tolerance in the interspecific cross Setaria italica×Setaria viridis.

Lufeng Qie,Yang Chai,Zhonglin Shang,Mingzhe Li,James Schnable,Wei Li,Binhui Liu,Xianmin Diao,Hui Zhi,Guanqing Jia,Wenying Zhang,Jean-Marc Lacape

doi:10.1371/journal.pone.0101868

Abstract

Drought tolerance is an important breeding target for enhancing the yields of grain crop species in arid and semi-arid regions of the world. Two species of Setaria, domesticated foxtail millet (S. italica) and its wild ancestor green foxtail (S. viridis) are becoming widely adopted as models for functional genomics studies in the Panicoid grasses. In this study, the genomic regions controlling germination and early seedling drought tolerance in Setaria were identified using 190 F7 lines derived from a cross between Yugu1, a S. italica cultivar developed in China, and a wild S. viridis genotype collected from Uzbekistan. Quantitative trait loci were identified which contribute to a number of traits including promptness index, radical root length, coleoptile length and lateral root number at germinating stage and seedling survival rate was characterized by the ability of desiccated seedlings to revive after rehydration. A genetic map with 128 SSR markers which spans 1293.9 cM with an average of 14 markers per linkage group of the 9 linkage groups was constructed. A total of eighteen QTLs were detected which included nine that explained over 10% of the phenotypic variance for a given trait. Both the wild green foxtail genotype and the foxtail millet cultivar contributed the favorite alleles for traits detected in this trial, indicating that wild Setaria viridis populations may serve as a reservoir for novel stress tolerance alleles which could be employed in foxtail millet breeding.

Highlights

Droughts reduce the water available in the soil to crop plants, producing stress and decreasing grain production [1]
root length (RL) and lateral root number (LRN) showed the largest changes between control and osmotic stress conditions
Similar biases were observed in related analysis [27,43,47]. These results suggest that many alleles from the wild parent S.viridis are lost in recombinant mapping populations, resulting in the considerably distorted segregation ratios of SSR markers observed in this study and others

Summary

Introduction

Droughts reduce the water available in the soil to crop plants, producing stress and decreasing grain production [1]. Global climate change, combined with increased urban demand for freshwater, means that agricultural production will be increasingly constrained by water supply while demand for food continues to grow [2]. In order to avoid catastrophic yield losses and to meet the food requirement of the rapidly growing world population it will be necessary to develop new crop varieties which can produce more grain while using less water. Previous genetic investigations have shown that drought tolerance is a complex trait controlled by multiple small effect QTLs (quantitative trait loci), and increasing of the efficiency of water use always certainly involves trade-offs with growth [3,4]. To date, no published study has examined the genetic architecture of drought tolerance in Setaria

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Conclusion