Identification of Genetic Loci on Chromosome 4B for Improving the Grain Number per Spike in Pre-Breeding Lines of Wheat

Jinpeng Zhang,Weihua Liu,Xinming Yang,Lihui Li,Xiuquan Li,Shenghui Zhou,Haiming Han,Ruixin Li,Yuqing Lu,Qifu Yao

doi:10.3390/agronomy12010171

Jinpeng Zhang, Weihua Liu + Show 8 more

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https://doi.org/10.3390/agronomy12010171

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Abstract

The grain number per spike (GNPS) is an important yield component, and much attention is given to the increase in GNPS for current yield improvement of common wheat. Here, a panel of 259 pre-breeding lines and elite commercial varieties were collected for the investigation of 12 agronomic traits, especially for spike-related traits, with 2-year replicates. The high correlation between GNPS and kernel number per spikelet (KNS) suggested that the high GNPS trait in our pre-breeding lines was mainly controlled by grain set number per spikelet. Genome-wide association studies (GWAS) using the 660K SNP genotyping assay suggested that a major locus on chromosomes 4BS contributed to the high GNPS trait, which contributed to 33% and 48% of the variation in KNS and GNPS, respectively. A good diagnostic KASP marker AX-109286577 flanking the 4BS locus was developed for easy selection of the large spike trait. Taken together, the results suggested that untapped rare allele variation in our pre-breeding lines can be used for improvement of the yield component of set grain number per spike.

Highlights

Common wheat (Triticum aestivum, allohexaploid, AABBDD genome) is the most widely grown crop globally, providing approximately 20% of the calories and protein in human diets [1]
It has been reported that spikelet fertility has increased during recent decades, especially in the European lines, and spikelet fertility is suggested as an essential driver of grain yield progress in wheat [22]
We reported that a panel of pre-breeding derivatives derived from the cross between high grain number per spike (GNPS) germplasm and diverse elite varieties carry prominent GNPS and kernel number per spikelet (KNS) phenotypes

Summary

Introduction

Common wheat (Triticum aestivum, allohexaploid, AABBDD genome) is the most widely grown crop globally, providing approximately 20% of the calories and protein in human diets [1]. Increasing wheat yield is a global challenge for food security, and six complementary approaches have been proposed, including optimizing developmental patterns to maximize spike fertility and grain number, and improving potential grain size and grain filling [2]. Wheat yield components are determined by three main factors, namely the spike number per unit area, grain number per spike (GNPS), and thousandkernel weight (TKW). Breeding practices have indicated that improvement of the spike number per unit area and TKW have increased to very high levels in China and other countries [3,4,5], while the increase in GNPS will be of widespread concern for future yield improvements [2,6]. A number of quantitative trait loci (QTLs) affecting grain number per spike have been mapped in common wheat. Some major QTLs were identified for GNPS on chromosomes 1A, 2B, 4B, 5B [7,8,9,10], for spikelet number per spike (SNS) on chromosome 2D, 4A, 5A, 6A, 7AL [11,12,13,14], and for kernel number per spikelet (KNS) on

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