Considering causal genes in the genetic dissection of kernel traits in common wheat

Abstract

Genetic factors controlling thousand-kernel weight (TKW) were characterized for their association with other seed traits, including kernel width, kernel length, ratio of kernel width to kernel length (KW/KL), kernel area, and spike number per m (SN). For this purpose, a genetic map was established utilizing a doubled haploid population derived from a cross between German winter wheat cultivars Pamier and Format. Association studies in a diversity panel of elite cultivars supplemented genetic analysis of kernel traits. In both populations, genomic signatures of 13 candidate genes for TKW and kernel size were analyzed. Major quantitative trait loci (QTL) for TKW were identified on chromosomes 1B, 2A, 2D, and 4D, and their locations coincided with major QTL for kernel size traits, supporting the common belief that TKW is a function of other kernel traits. The QTL on chromosome 2A was associated with TKW candidate gene TaCwi-A1 and the QTL on chromosome 4D was associated with dwarfing gene Rht-D1. A minor QTL for TKW on chromosome 6B coincided with TaGW2-6B. The QTL for kernel dimensions that did not affect TKW were detected on eight chromosomes. A major QTL for KW/KL located at the distal tip of chromosome arm 5AS is being reported for the first time. TaSus1-7A and TaSAP-A1, closely linked to each other on chromosome 7A, could be related to a minor QTL for KW/KL. Genetic analysis of SN confirmed its negative correlation with TKW in this cross. In the diversity panel, TaSus1-7A was associated with TKW. Compared to the Pamier/Format bi-parental population where TaCwi-A1a was associated with higher TKW, the same allele reduced grain yield in the diversity panel, suggesting opposite effects of TaCwi-A1 on these two traits.

Artificial selection causes significant linkage disequilibrium among multiple unlinked genes in Australian wheat

“…Ethylene production can be induced under heat stress, which limits grain yield (Hays, Do, Mason, Morgan, & Finlayson, 2007). Given the large number of potential genes targeted by artificial selection, these sweeps were the largest two sweeps in this study spanning and TaSAP1-7A as well as a number of yield, different yield components, and quality QTL (Bennett, Izanloo, Edwards, et al, 2012;Maphosa et al, 2013;Mohler et al, 2016;Sukumaran, Lopes, Dreisigacker, & Reynolds, 2018). The average size of LD blocks in this germplasm was previously reported to be ~19 cM .…”

“…The third largest sweep identified here was the region 7A‐371.3:399.2 spanning 27.9 cM and was detected in all subpopulations using all statistical tests. This region encompasses the genes TaSus1‐7A and TaSAP1‐7A as well as a number of yield, different yield components, and quality QTL (Bennett, Izanloo, Edwards, et al, ; Bennett, Reynolds, et al, ; Maphosa et al, ; Mohler et al, ; Sukumaran, Lopes, Dreisigacker, & Reynolds, ). The average size of LD blocks in this germplasm was previously reported to be ~19 cM (Joukhadar et al, ).…”

“…These six regions were detected in the Post70 population as well as in some states (Table ). The 6A region involved the well‐documented grain yield gene TaGw2‐6A , while the 6B region could potentially be the homoeologous gene TaGw2‐6B (Mohler et al, ). The 6A sweep was previously reported in multiple studies to be associated with different yield and yield component traits as well as some quality traits such as grain protein content and water‐soluble carbohydrates (Bennett, Reynolds, et al, ; Maphosa et al, ; Sukumaran, Dreisigacker, et al, ; Sukumaran et al, ).…”

Comparative analysis of genetic architectures for nine developmental traits of rye

“…Kernel length in rice is controlled by 17 QTL (Zhao et al 2017) and each chromosome group of wheat and barley contains at least one QTL for thousand-kernel weight (Mohler et al 2016; Ogrodowicz et al 2017; Lex et al 2014). Numerous QTL spread across wheat, barley and rye genomes control plant height, spike length and heading date (Cui et al 2011; Mikołajczak et al 2017; Ogrodowicz et al 2017; Miedaner et al 2012; Myśków et al 2014 and this paper).…”

TaDA1, a conserved negative regulator of kernel size, has an additive effect with TaGW2 in common wheat (Triticum aestivum L.)

“…With growing global population and increasing demand for wheat, wheat yields must be further improved. Grain weight and size are major components of wheat yield and are therefore key targets for the further improvement of this crop (Li and Yang, ; Mohler et al , ; Xie et al , ). Many genes regulating wheat grain weights have been identified using comparative genomics approaches, including TaGW2 (Qin et al , ; Simmonds et al , ; Su et al , ), Ta CKX2 (Zhang et al , ), TaGS5 (Ma et al , ; Wang et al , ), TaCYP78A3 (Ma et al , ), TaTGW6 (Hanif et al , ; Hu et al , ), TaFlo2‐A1 (Sajjad et al , ), and TaAGP‐S1 and TaAGP‐L (Hou et al , ).…”