Genetic variability of aquaporin expression in maize: From eQTLs to a MITE insertion regulating PIP2;5 expression

Area of Science:

• Plant molecular biology
• Genetics
• Physiology

Background:

• Plant aquaporins, specifically plasma membrane intrinsic proteins (PIPs), are crucial for cellular homeostasis, water transport, and stress responses.
• Understanding the genetic regulation of PIP gene expression is vital for plant adaptation but remains largely unknown.

Purpose of the Study:

• To investigate the genetic basis of expression variability in four maize PIP genes in leaves.
• To identify regulatory elements and mechanisms influencing PIP gene expression.

Main Methods:

• Expression quantitative trait locus (eQTL) mapping was performed on a panel of 252 maize hybrids.
• Genome-wide association studies (GWAS) were used to identify genetic loci associated with PIP transcript abundance.
• Sequence comparison and in vivo reporter assays were employed to characterize specific regulatory polymorphisms.

Main Results:

• Significant genetic variability in PIP transcript levels was observed across the maize panel, varying by PIP isoform.
• Numerous local and distant eQTLs were identified, highlighting natural diversity in PIP gene expression.
• A specific eQTL for PIP2;5 was linked to a transposon insertion in its promoter region.

Conclusions:

• Natural genetic variation significantly impacts maize PIP gene expression in leaves.
• Transposon insertions in regulatory regions can contribute to differential gene expression.
• This research provides insights into PIP gene regulation and its role in plant physiological and stress adaptation processes.