Genetic and physiological bases for variation in water use efficiency in canola

Harsh Raman,Brett Mcvittie,Sureshkumar Balasubramanian,Graham Farquhar,Rosy Raman,Avilash Singh Yadav,Simon Diffey,Lauren Borg

doi:10.1002/fes3.237

Abstract

AbstractDrought stress due to water deficiency threatens production of canola worldwide. Carbon isotope discrimination (Δ13C), a trait that can be used to assess efficient water use, provides an opportunity to exploit natural variation in canola for stable production. Here, we show that substantial genetically controlled phenotypic variation in water use efficiency (WUE) component trait, Δ13C (20.4 to 23.6‰) exists among accessions of canola. Quantitative trait loci (QTL) analysis revealed ten loci for Δ13C, each accounting for 2.5% to 16.5% of the genotypic variation. One of the significant QTL for Δ13C was co‐localized with a QTL for flowering time, a trait implicated in drought escape and was mapped in the vicinity of the FLOWERING LOCUS T (FT) on chromosome A07. Gene expression analyses revealed that among FT paralogs, BnC6.FTb expression was significantly correlated (r = 0.33, p < .01) with variation in Δ13C across at least two environments in a canola DH population. Integration of data based on instantaneous single leaf gas exchange, dry matter Δ13C, and whole plant measurements suggests a possible trade‐off between early flowering and WUE. Our findings provide insights into the complexity of Δ13C and WUE which could enable the development of canola varieties resilient to drought and increasing canola productivity under water‐limited conditions.

Highlights

Drought is a major environmental stress that continues to threaten the sustainable production and profitability of various agricultural crops, including canola—the second most important oilseed crop used worldwide for healthy vegetable oil for human consumption, feed stocks, and biodiesel production
2.2.2 | Evaluation for Δ13C variation in doubled haploid (DH) population integrated with Δ13C data for all SAgS DH lines to see the relationships of Δ13C with productivity traits across environments
We used Empirical Best Linear Unbiased Predictors (EBLUPS) of Δ13C and considered their correlation with previously published FLOWERING LOCUS T (FT) expression data of SAgS DH population grown under field conditions (Raman, Raman, et al, 2019)

Summary

| INTRODUCTION

Drought (water deficit) is a major environmental stress that continues to threaten the sustainable production and profitability of various agricultural crops, including canola—the second most important oilseed crop used worldwide for healthy vegetable oil for human consumption, feed stocks, and biodiesel production. Studies in model plants have identified candidate genes such as MPK12, FRIGIDA, ERECTA as well as receptors for the abscisic acid (ABA) response to be involved in WUE (Des Marais et al, 2014; Karaba et al, 2007; Kuromori et al, 2016; Kuromori et al, 2010; Kuromori, Sugimoto, & Shinozaki, 2011; Lovell et al, 2013; Masle et al, 2005; Papacek, Christmann, & Grill, 2019; Zhang et al, 2016; Zhao, Hu, Li, Yao, & Liu, 2016; Zhao, Chan, et al, 2016) The knowledge of such pathways and their manipulation even in closely related major agricultural crops such as canola and Indian mustard is rather limited. We confirm that the early flowering allele is associated with large Δ13C, high CO2 assimilation rate, and high stomatal conductance, especially under water stress conditions in a mapping population

| MATERIALS AND METHODS

Objective

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