Identification of a Novel Allele of TaCKX6a02 Associated with Grain Size, Filling Rate and Weight of Common Wheat

Abstract

Cytokinin oxidase (CKX) plays a crucial role in plant growth and development by reversibly inactivating cytokinin (CTK). Twenty-four primer pairs, designed from ESTs of the TaCKX genes family of common wheat, were used to identify their allelic variations associated with grain size, weight, and filling rate in 169 recombinant inbred lines (RIL) derived from Jing 411 × Hongmangchun 21. TaCKX6a02, a member of TaCKX gene family, amplified by primer pair T31–32, showed a close association with grain traits in this RIL population. Statistical analysis indicated that allelic variation of TaCKX6a02 had significant correlation with grain size, weight, and filling rate (GFR; P < 0.001) under varied environments. The TaCKX6a02-D1a allele from Jing411 significantly increased grain size, weight and grain filling rate, compared with TaCKX6a02-D1b from Hongmangchun 21. TaCKX6a02 was located on chromosome 3DS in the interval of Xbarc1119 and Xbarc1162, with a genetic distance of 1.4 cM. The location was further confirmed using Chinese Spring nulli–tetrasomic lines. A major QTL (quantitative trait locus) tightly linked to TaCKX6a02 was detected in the RIL population, explaining 17.1~38.2% of phenotype variations for grain size, weight, GFRmax and GFRmean in different environments. In addition, significant effects of variations of TaCKX6a02 on grain weight and GFR were further validated by association analysis among 102 wheat varieties in two cropping seasons. 12.8~35.1% of phenotypic variations were estimated for these genotypes. A novel 29-bp InDel behind the stop codon was detected by DNA sequence analysis between the two alleles of TaCKX6a02-D1. The gene-specific marker, TKX3D, was designed according to the novel variation, and can be used in marker-assisted selection (MAS) for grain size, weight, and GFR in common wheat.

Cloning and Characterization of TaTGW-7A Gene Associated with Grain Weight in Wheat via SLAF-seq-BSA

“…Therefore, other methods should also be used for identifying functional genes in wheat. In our previous studies, several genes including TaCKOX6a02 on 3DS (Lu et al, 2015), Tackx4 on 3AL (Chang et al, 2015), and TaTGW6 on 4AL (Hu et al, 2016) associated with TGW were identified based on the homology analysis of rice genes.…”

“…This approach was successfully used in detection of QTL, fine mapping of candidate genes and development of molecular markers in high plants (Trick et al, 2012; Qin et al, 2015; Xu et al, 2015a,b). In our previous studies, several genes for TGW, including TaCKOX6a02 (Lu et al, 2015), Tackx4 (Chang et al, 2015), and TaTGW6 (Hu et al, 2016), have been identified using RIL from a cross between Jing 411 and Hongmangchun 21. The two parents, Jing 411 and Hongmangchun 21, showed large differences in grain size, TGW, and grain filling rate.…”

High-Throughput Sequencing Reveals Single Nucleotide Variants in Longer-Kernel Bread Wheat

“…Some quantitative trait loci (QTLs) controlling grain shape and size in bread wheat have been mapped through marker analysis in different wheat populations ( Breseghello and Sorrells, 2006 ; Wu et al, 2015 ). Many of them were associated with the orthologs of rice grain traits QTLs ( Lu et al, 2015 ; Wu et al, 2015 ; Zanke et al, 2015 ). For example, GRAIN SIZE 3 (GS3) is a major QTL for rice grain length and weight ( Fan et al, 2006 ), TaGS-D1 was the syntenic gene in wheat ( Zhang et al, 2014 ).…”

Silencing ofTaCKX1mediates expression of otherTaCKXgenes to increase grain yield in wheat

“…The role of other TaCKX genes in wheat was analysed based on natural TaCKX variation. Haplotype variants of TaCKX6a02 and TaCKX6-D1 were related to higher filling rate and grain size (Zhang et al, 2012; Lu et al, 2015). QTL found in recombinant inbred lines containing a higher copy number of TaCKX4 was associated with higher chlorophyll content and grain size (Chang et al, 2015).…”