Abstract
SummaryDrought is a major abiotic stress that threatens maize production globally. A previous genome‐wide association study identified a significant association between the natural variation of ZmTIP1 and the drought tolerance of maize seedlings. Here, we report on comprehensive genetic and functional analysis, indicating that ZmTIP1, which encodes a functional S‐acyltransferase, plays a positive role in regulating the length of root hairs and the level of drought tolerance in maize. We show that enhancing ZmTIP1 expression in transgenic Arabidopsis and maize increased root hair length, as well as plant tolerance to water deficit. In contrast, ZmTIP1 transposon‐insertional mutants displayed the opposite phenotype. A calcium‐dependent protein kinase, ZmCPK9, was identified as a substrate protein of ZmTIP1, and ZmTIP1‐mediated palmitoylation of two cysteine residues facilitated the ZmCPK9 PM association. The results of this research enrich our knowledge about ZmTIP1‐mediated protein S‐acylation modifications in relation to the regulation of root hair elongation and drought tolerance. Additionally, the identification of a favourable allele of ZmTIP1 also provides a valuable genetic resource or selection target for the genetic improvement of maize.
Highlights
Maize is an essential cereal crop that is grown worldwide, providing a major resource for food, feed, and industrial materials
We reported the results of a comprehensive genetic and functional characterization of ZmTIP1, which revealed that genetic variations in the promoter region but not the protein-coding region are responsible for the gene functional variation in drought tolerance
A SNP within GRMZM2G087806 residing on chromosome 9 was identified in our previous research and found to be significantly associated with drought tolerance (ÀLog10P = 1.79 9 10À6) in maize seedlings (Wang et al, 2016)
Summary
Maize is an essential cereal crop that is grown worldwide, providing a major resource for food, feed, and industrial materials. Due to the complexity of the drought tolerance trait, which is associated with a variety of physiological parameters and controlled by multiple genes, improving drought tolerance in maize has been difficult. As a cross-pollinated crop, maize is thought to be an ideal model plant for conducting association studies because of its great genetic diversity and genome-wide rapid linkage disequilibrium (LD) decay (Gore et al, 2009; Yan et al, 2009). Recent progress in genome-wide association studies (GWAS) has facilitated the genetic dissection of several complex traits, including b-carotene concentration, oil biosynthesis in maize kernels, photoperiod sensitivity and seedling drought tolerance (Li et al, 2013; Wang et al, 2016; Yan et al, 2010; Yang et al, 2013). GWAS provides valuable information about the genetic loci underlying a specific trait, the accurate identification of the underlying allelic variation responsible for a specific trait, as well as the functional mechanism, typically demands additional studies
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