Genome‐wide association study revealed TaHXK3‐2A as a candidate gene controlling stomatal index in wheat seedlings

Abstract

Stomata are important channels for the control of gas exchange between plants and the atmosphere. To examine the genetic architecture of wheat stomatal index, we performed a genome-wide association study (GWAS) using a panel of 539 wheat accessions and 450 678 polymorphic single nucleotide polymorphisms (SNPs) that were detected using wheat-specific 660K SNP array. A total of 130 SNPs were detected to be significantly associated with stomatal index in both leaf surfaces of wheat seedlings. These significant SNPs were distributed across 16 chromosomes and involved 2625 candidate genes which participate in stress response, metabolism and cell/organ development. Subsequent bulk segregant analysis (BSA), combined with GWAS identified one major haplotype on chromosome 2A, that is responsible for stomatal index on the abaxial leaf surface. Candidate gene association analysis revealed that genetic variation in the promoter region of the hexokinase gene TaHXK3-2A was significantly associated with the stomatal index.Moreover, transgenic analysis confirmed that TaHXK3-2A overexpression in wheat decreased the size of leaf pavement cells but increased stomatal density through the glucose metabolic pathway, resulting in drought sensitivity among TaHXK3-2A transgenic lines due to an increased transpiration rate. Taken together, these results provide valuable insights into the genetic control of the stomatal index in wheat seedlings.

A comprehensive overview of breeding strategy to improve phenotypic and quality traits in Valeriana jatamansi Jones

“…There is the presence of paracytic stomata on both abaxial and adaxial surfaces of the leaf, however higher stomatal density was observed on the abaxial surface [ 4 ]. Interestingly, the stomatal density is also regulated by various genes and have been reported in other crops too [ 44 , 45 , 46 ]. Being sciophytic this plant shows high nitrogen content/leaf area, high leaf mass/leaf area unit, thicker leaves having higher respiration rate and chloroplasts under full irradiance compared to net shade plants [ 47 ].…”

TaSINA2B, interacting with TaSINA1D, positively regulates drought tolerance and root growth in wheat (Triticum aestivum L.)

“…Mao et al (2020) found that a 3 bp insertion in the TaSNAC8‐6A promoter increased the transcription of TaSNAC8‐6A to enhance drought tolerance. In turn, promoter variation of TaNAC071‐A and TaHXK3‐2A also found to elicit the transcription of target genes, thereby contributing to the regulation of responses to drought stress (Li et al, 2022; Mao et al, 2022). In this study, we found two types of promoters, TaSINA2B I and TaSINA2B II , from 192 wheat accessions (Figure 2a).…”

The battle of crops against drought: Genetic dissection and improvement

“…Besides SR, the degrees of leaf rolling and wilting, stomatal size and density, and root architecture are important traits which contribute to drought resistance (Krannich et al, 2015; Caine et al, 2019; Dunn et al, 2019; Li et al, 2022). DROUGHT1 ( DROT1 ), encoding a COBRA‐like protein, was identified in a GWAS in rice based on an index combining the degree of leaf rolling with the color of seedling leaves under drought conditions (Sun et al, 2022b).…”