Identification of Genetic Loci Affecting Flag Leaf Chlorophyll in Wheat Grown under Different Water Regimes

Abstract

Chlorophyll content of the flag leaf is an important trait for drought resistance in wheat under drought stress. Understanding the regulatory mechanism of flag leaf chlorophyll content could accelerate breeding for drought resistance. In this study, we constructed a recombinant inbred line (RIL) population from a cross of drought-sensitive variety DH118 and drought-resistant variety Jinmai 919, and analyzed the chlorophyll contents of flag leaves in six experimental locations/years using the Wheat90K single-nucleotide polymorphism array. A total of 29 quantitative trait loci (QTLs) controlling flag leaf chlorophyll were detected with contributions to phenotypic variation ranging from 4.67 to 23.25%. Twelve QTLs were detected under irrigated conditions and 18 were detected under dryland (drought) conditions. Most of the QTLs detected under the different water regimes were different. Four major QTLs (Qchl.saw-3B.2, Qchl.saw-5A.2, Qchl.saw-5A.3, and Qchl.saw-5B.2) were detected in the RIL population. Qchl.saw-3B.2, possibly more suitable for marker-assisted selection of genotypes adapted to irrigated conditions, was validated by a tightly linked kompetitive allele specific PCR (KASP) marker in a doubled haploid population derived from a different cross. Qchl.saw-5A.3, a novel stably expressed QTL, was detected in the dryland environments and explained up to 23.25% of the phenotypic variation, and has potential for marker-assisted breeding of genotypes adapted to dryland conditions. The stable and major QTLs identified here add valuable information for understanding the genetic mechanism underlying chlorophyll content and provide a basis for molecular marker–assisted breeding.

Identification of genetic loci for flag-leaf-related traits in wheat (Triticum aestivum L.) and their effects on grain yield

“…The developed KASP markers were used to detect previously identified QTL in the DH118 × Jinmai 919 population as a means of validation. Following genotyping, the validation population was divided into two groups and differences in flag-leaf-related traits between the groups were assessed by t -tests in SAS V8.0 ( Yang et al, 2022 ).…”

“…Many quantitative trait loci (QTL) for flag-leaf-related traits have been reported in wheat. A QTL for FLW on chromosome 5A and 5B was fine mapped in previous studies (Xue et al, 2013;Zhao et al, 2022). A total of 38 QTL for flag-leaf-related traits was identified in a recombinant inbred line (RIL) population, among which were three stable QTL on chromosomes 4B, 5B, and 6B (Fan et al, 2015).…”

Identification and validation of quantitative trait loci for chlorophyll content of flag leaf in wheat under different phosphorus treatments

“…The analysis of variance (ANOVA), correlation analysis, and the Student’s t -test ( P < 0.05) of measured phenotype values in different environments were performed by SPSS 21.0 software (SPSS, Chicago, IL, USA; ) ( Yang et al., 2022 ). SAS (SAS Institute, Cary, NC, USA; ) was used for calculating the best linear unbiased prediction (BLUP) and broad sense heritability ( H 2 ) for chlorophyll content of flag leaves in different environments ( Smith et al., 1998 ).…”

“…Mapping and cloning genes controlling chlorophyll are essential for studying the genetic characteristics of this trait ( Thomas and Ougham, 2014 ; Rasheed et al., 2020 ). With increased research on chlorophyll-related traits in recent years, over 900 QTLs for chlorophyll content have been identified in rice, and at least eight stay-green related genes, including DYE1 , SGR , and EF8 , have been cloned ( Morita et al., 2009 ; Feng et al., 2014 ; Yamatani et al., 2018 ; Yang et al., 2022 ). Research on the genetic mechanism that regulates chlorophyll in wheat lags behind model crops such as rice ( Gupta et al., 2020 ).…”

“…Research on the genetic mechanism that regulates chlorophyll in wheat lags behind model crops such as rice ( Gupta et al., 2020 ). Under drought, high temperature, light intensity, and nutrient stress, QTL analysis of chlorophyll content has been performed ( Fang et al., 2004 ; Li et al., 2010 ; Vijayalakshmi et al., 2010 ; Christopher et al., 2018 ; Maulana et al., 2018 ; Kamal et al., 2019 ), and hundreds of QTLs were identified on 21 chromosomes of wheat ( Kumar et al., 2010 ; Li et al., 2010 ; Vijayalakshmi et al., 2010 ; Zhang et al., 2010 ; Kumar et al., 2012 ; Ilyas et al., 2014 ; Saleh et al., 2014 ; Barakat et al., 2015 ; Yang et al., 2016a ; Yang et al., 2016b ; Shi et al., 2017 ; Christopher et al., 2018 ; Puttamadanayaka et al., 2020 ; Yan et al., 2020 ; Yang et al., 2022 ). However, most studies used low-density SSR markers and were only identified in a few years/environments.…”