Studies On The Differences Among Wheat Seed In Zinc Absorption And Distribution And Transcriptomic Analysis

Zinc(Zinc,Zn)is one of the essential trace elements for living organisms.More than 30%of the world’s population is deficient in zinc,which seriously endangers human health.At least 100 million people in China have been in a state of "hidden hunger" caused by zinc deficiency.Humans mainly acquire nutrients such as Zn through food.Wheat is the staple food of nearly 40%of the world’s population and is one of the main food crops in China.However,the low Zn concentration in wheat grains leads to a generally low zinc intake among people who rely on wheat as their staple food.Therefore,increasing wheat grain Zn concentration can effectively improve the zinc deficiency status of Chinese residents.This experiment analyzed the differences in Zn uptake and distribution among six genotypes,including four with higher grain Zn concentration(Triticale,cultivated einkorn wheat,Xinjiang wheat,and Ningchun No.2)and two with lower grain Zn concentration(Ningchun No.19 and Ningchun No.41).The study also compared the differences in transcriptomics upon Zn deficiency among three genotypes,including the cultivated einkorn wheat,Ningchun No.2 and Ningchun No.19.This study provided valuable insights and paved the way for further studies.The main results were as follows:1.In this study,after growing for 14 days in 1/4 Hoagland solution,the root Zn absorption efficiency of the cultivated einkorn wheat was significantly higher than that of the other wheat.The dry matter accumulation of 14-days-old wheat seedlings was mainly controlled by wheat seed,and was less affected by Zn deficiency stress.Xinjiang wheat has the highest dry matter accumulation efficiency,while Triticale has the lowest dry matter accumulation efficiency.2.Due to the higher grain number and grain weight per spike,the tested low Zn wheat allocated higher proportion of aboveground Zn into grains than the genotypes with higher grain Zn concentration.(2)Zn uptake efficiency may be a key factor affecting grain zinc concentration.(3)Grain is the largest Zn sink in wheat.There was no significant difference in Zn concentration between the grains from main spike and the grains from tillers.(4)The loading of Zn to rachis may be a limiting factor for Zn accumulation in common wheat.(5)There may be a mechanism that restricts the transport of Zn in the nodes of cultivated einkorn wheat.(6)Genotypes with higher surface to volume ratio may not necessarily have higher grain Zn concentration.3.Under zinc deficiency,Ningchun No.19 would upregulated the ion homeostasis pathway,while Ningchun No.2 upregulated the passive transport pathway.Based on the differential gene expression between Ningchun No 2 and Ningchun No 19,it is speculated that the study of Zn absorption efficiency in common wheat can start with gene expression regulation,secondary metabolite synthesis,and ion transmembrane transport.Zinc deficiency had a larger impact on the photosynthesis of Ningchun No 19,while had a larger impact on the synthesis and metabolism of secondary metabolites of Ningchun No 2.The up-regulated pathway in response to Zn deficiency in cultivated einkorn wheat is similar to that commonly upregulated in common wheat under Zn deficiency,while the down-regulated pathway is similar to that of Ningchun No 2,which has higher Zn absorption efficiency.