Association mapping uncovers maize ZmbZIP107 regulating root system architecture and lead absorption under lead stress

Abstract

Lead (Pb) is a highly toxic contaminant to living organisms and the environment. Excessive Pb in soils affects crop yield and quality, thus threatening human health via the food chain. Herein, we investigated Pb tolerance among a maize association panel using root bushiness (BSH) under Pb treatment as an indicator. Through a genome-wide association study of relative BSH, we identified four single nucleotide polymorphisms (SNPs) and 30 candidate genes associated with Pb tolerance in maize seedlings. Transcriptome analysis showed that four of the 30 genes were differentially responsive to Pb treatment between two maize lines with contrasting Pb tolerance. Among these, the ZmbZIP107 transcription factor was confirmed as the key gene controlling maize tolerance to Pb by using gene-based association studies. Two 5’ UTR_variants in ZmbZIP107 affected its expression level and Pb tolerance among different maize lines. ZmbZIP107 protein was specifically targeted to the nucleus and ZmbZIP107 mRNA showed the highest expression in maize seedling roots among different tissues. Heterologous expression of ZmbZIP107 enhanced rice tolerance to Pb stress and decreased Pb absorption in the roots. Our study provided the basis for revelation of the molecular mechanism underlying Pb tolerance and contributed to cultivation of Pb-tolerant varieties in maize.

An Integration of Linkage Mapping and GWAS Reveals the Key Genes for Ear Shank Length in Maize

“…The Cyclin11 expression levels were quantified by conducting RT-qPCR with the SYBR qPCR SuperMix Plus (Novoprotein, Nanjing, China), the primers of RT-qPCR were listed in Table S8 . ZmActin served as a reference gene, and the 2 −ΔΔCT method was employed to calculate the relative expressions of Cyclin11 [ 53 ]. Three biological repetitions and three technical replicates were carried out for each sample.…”

“…To understand the subcellular localization of Cyclin11 , we cloned the full-length coding sequence of Cyclin11 without the stop codon into the reporter vector pCAMBIA2300-eGFP, generating the p35S: Cyclin11 -eGFP fusion expression vector. The fusion vector was then introduced into the Nicotiana benthamiana leaves for transient expression using the Agrobacterium-mediated method [ 53 ]. The p35S: eGFP vector served as the negative control.…”

Flavonoid metabolism plays an important role in response to Pb stress in maize at seedling stage

“…Pb stress is one of the most common heavy metal stresses in soil and is increasing with the development of industry [45]. Previous studies have shown that root development, including lateral root formation and root morphological parameters, including length, surface area, volume, bushiness, and biomass, is inhibited by Pb [46,47]. Root cell viability was attenuated, leading to induced cell death under Pb stress [48].…”

A genome-wide co-expression network analysis revealed ZmNRAMP6-mediated regulatory pathway involved in maize tolerance to lead stress

“…The expression level of ZmNRAMP6 was quanti ed by conducting RT-qPCR using SYBR qPCR SuperMix Plus (Novoprotein, Nanjing, China). The ZmActin gene was used as the internal reference to normalize the expression level of ZmNRAMP6 and the 2 -ΔΔCT method was applied to calculate the relative expression levels of ZmNRAMP6 (Hou et al 2022a). Three biological repetitions were performed for each sample with three technical replicates included in a single biological replication.…”