Genetic factors of grain cadmium concentration in Polish wheat (Triticum polonicum L.)

https://academic.oup.com/plphys/advance-article-abstract/doi/10.1093/plphys/kiae353/7698905?redirectedFrom=fulltext&login=false

Plant Physiology, kiae353,25 June 2024

Yiran Cheng,Rui Liu,Tian Yang,Shan Yang,Jia Chen,Yiwen Huang,Dan Long,Jian Zeng,Dandan Wu,Houyang Kang,Xing Fan,Lina Sha,Haiqin Zhang,Yonghong Zhou,Yi Wang

Abstract

Wheat (Triticum aestivumL.) is one of the most important crops worldwide and a major source of human cadmium (Cd) intake. Limiting grain Cd concentration (Gr_Cd_Conc) in wheat is necessary to ensure food safety. However, the genetic factors associated with Cd uptake, translocation and distribution and Gr_Cd_Conc in wheat are poorly understood. Here, we mapped quantitative trait loci (QTLs) for Gr_Cd_Conc and its related transport pathway using a recombinant inbred line (RIL) population derived from 2 Polish wheat varieties (RIL_DT; dwarf Polish wheat [DPW] and tall Polish wheat [TPW]). We identified 29 novel major QTLs for grain and tissue Cd concentration; 14 novel major QTLs for Cd uptake, translocation, and distribution; and 27 major QTLs for agronomic traits. We also analyzed the pleiotropy of these QTLs. Six novel QTLs (QGr_Cd_Conc-1A,QGr_Cd_Conc-3A,QGr_Cd_Conc-4B,QGr_Cd_Conc-5B,QGr_Cd_Conc-6A, andQGr_Cd_Conc-7A) for Gr_Cd_Conc explained 8.16% to 17.02% of the phenotypic variation.QGr_Cd_Conc-3A,QGr_Cd_Conc-6A, andQGr_Cd_Conc-7Apleiotropically regulated Cd transport; 3 other QTLs were organ-specific for Gr_Cd_Conc. We fine-mapped the locus ofQGr_Cd_Conc-4Band identified the candidate gene asCation/Ca exchanger 2(TpCCX2-4B), which was differentially expressed in DPW and TPW. It encodes an endoplasmic reticulum membrane/plasma membrane–localized Cd efflux transporter in yeast. Overexpression ofTpCCX2-4Breduced Gr_Cd_Conc in rice. The average Gr_Cd_Conc was significantly lower inTpCCX2-4BDPWgenotypes than inTpCCX2-4BTPWgenotypes of the RIL_DT population and 2 other natural populations, based on a Kompetitive allele-specific PCR marker derived from the different promoter sequences betweenTpCCX2-4BDPWandTpCCX2-4BTPW. Our study reveals the genetic mechanism of Cd accumulation in wheat and provides valuable resources for genetic improvement of low–Cd-accumulating wheat cultivars.