Detection of two major grain yield QTL in bread wheat (Triticum aestivum L.) under heat, drought and high yield potential environments

Abstract

A large proportion of the worlds' wheat growing regions suffers water and/or heat stress at some stage during the crop growth cycle. With few exceptions, there has been no utilisation of managed environments to screen mapping populations under repeatable abiotic stress conditions, such as the facilities developed by the International Wheat and Maize Improvement Centre (CIMMYT). Through careful management of irrigation and sowing date over three consecutive seasons, repeatable heat, drought and high yield potential conditions were imposed on the RAC875/Kukri doubled haploid population to identify genetic loci for grain yield, yield components and key morpho-physiological traits under these conditions. Two of the detected quantitative trait loci (QTL) were located on chromosome 3B and had a large effect on canopy temperature and grain yield, accounting for up to 22 % of the variance for these traits. The locus on chromosome arm 3BL was detected under all three treatments but had its largest effect under the heat stress conditions, with the RAC875 allele increasing grain yield by 131 kg ha(-1) (or phenotypically, 7 % of treatment average). Only two of the eight yield QTL detected in the current study (including linkage groups 3A, 3D, 4D 5B and 7A) were previously detected in the RAC875/Kukri doubled haploid population; and there were also different yield components driving grain yield. A number of discussion points are raised to understand differences between the Mexican and southern Australian production environments and explain the lack of correlation between the datasets. The two key QTL detected on chromosome 3B in the present study are candidates for further genetic dissection and development of molecular markers.

Ppd1, Vrn1, ALMT1 and Rht genes and their effects on grain yield in lower rainfall environments in southern Australia

“…In the Trident/Molineux population, the positive allele for grain yield on chromosome 4D came from Trident (Kuchel et al 2007). However, in the RAC875/ Kukri population, the positive allele in southern Australia came from RAC875 (Bennett et al 2012a), but in a heat environment in Mexico it came from Kukri (Bennett et al 2012b). Similarities to these interactions and effects were observed in our study (Tables 6 and 9), but clearly more work is required to determine the contribution of ALMT1 to the QTL effects observed in the Trident/Molineux and RAC875/Kukri populations.…”

“…Molineux carried ALMT1-I, cv. Kukri carried ALMT1-V, and the breeding lines RAC875 carried ALMT1-I, so the Trident/Molineux population studied by Kuchel et al (2007) and the RAC875/Kukri population studied by Bennett et al (2012aBennett et al ( , 2012b were both segregating at the ALMT1 locus. ALMT1 is located on chromosome 4D, and in both populations, a QTL was detected on this chromosome.…”

Quantifying Wheat Sensitivities to Environmental Constraints to Dissect Genotype × Environment Interactions in the Field

“…Overall, this analysis confirmed the positive constitutive effect of the Drysdale allele at this QTL on number of spikes and explained the null effect on yield observed by Parent et al (2015) due to the tradeoff between the number of spikes, the number of seeds per spike, and seed weight. The second data set included 48 lines of the RAC875 3 Kukri double haploid population cultivated in the three environments of 2009 and for which a QTL for yield and thousand kernel weight had been observed on chromosome 3B (marker Xwmc236; Bennett et al, 2012aBennett et al, , 2012bBonneau et al, 2013). This QTL was highly dependent on the environment, but no clear relationship had been observed with quantitative environmental variables.…”

“…The method itself can now be applied to larger data sets and populations, once plant development and meteorological data are recorded. More specifically, this study deciphered the strong QTL 3 E interaction of the QTL on chromosome 3B (qYDH.3BL), a major yield QTL but highly dependent on environmental conditions (Bennett et al, 2012a(Bennett et al, , 2012bBonneau et al,2013;Maphosa et al, 2014). This should facilitate the cloning of the gene or genes underlying the 3B QTL by informing on the conditions associated with a positive impact on yield for each allele.…”

“…This QTL overlaps with QKpsl.aww-1B for grain per spikelet and yields QTL QYld.aww-1B on the second population, RAC875/ Kukri (Bennett et al, 2012a), but with lower effects than in Drysdale/Gladius. A QTL found on chromosome 3B, qYDH.3BL, in the RAC875 3 Kukri double haploid population (Bennett et al, 2012b;Bonneau et al, 2013) controlled yield and thousand kernel weight and showed a strong interaction with the environment. qYDH.3BL of RAC875/Kukri (Bonneau et al, 2013) also segregates in Drysdale/Gladius (Maphosa et al, 2014), as confirmed by Bonneau et al (2013).…”