GhGPAT12/25 Are Essential for the Formation of Anther Cuticle and Pollen Exine in Cotton (Gossypium hirsutum L.)

Abstract

Glycerol-3-phosphate acyltransferases (GPATs), critical for multiple biological processes like male fertility, have been extensively characterized. However, their precise functions and underlying regulatory mechanism in cotton anther development are unclear. This research demonstrated the importance of GhGPAT12/25 (a paralogs pair on A12/D12 sub-chromosome of cotton) to regulate the degradation of tapetum, anther cuticle formation, and pollen exine development. GhGPAT12 and GhGPAT25 exhibited specifically detected transcripts in tapetum and pollen exine during the early anther developmental stages. GhGPAT12/25 are sn-2 glycerol-3-phosphate acyltransferases and can transfer the acyl group of palmitoyl-CoA to glycerol-3-phosphate (G3P). CRISPR/Cas9-mediated knockout identified the functional redundancy of GhGPAT12 and GhGPAT25. Knockout of both genes caused completely male sterility associated with abnormal anther cuticle, swollen tapetum, and inviable microspores with defective exine and irregular unrestricted shape. RNA-seq analysis showed that the loss of function of GhGPAT12/25 affects the processes of wax metabolic, glycerol monomer biosynthesis, and transport. Consistently, cuticular waxes were dramatically reduced in mutant anthers. Yeast one-hybrid system (Y1H), virus-induced gene silencing (VIGS), and dual-luciferase (LUC) assays illustrated that GhMYB80s are likely to directly activate the expression of GhGPAT12/25. This study provides important insights for revealing the regulatory mechanism underlying anther development in cotton.

Use of CRISPR/Cas9-Based Gene Editing to Simultaneously Mutate Multiple Homologous Genes Required for Pollen Development and Male Fertility in Maize

“…The CRISPR/Cas9 system, as a highly efficient and convenient genome editing tool, has been successfully used for simultaneously mutating homologous GMS genes in crops, including bread wheat [22,23], maize [24], and cotton [41]. The corresponding GMS genes include TaMs45-A/B/D, TaMsNP1-A/B/D, ZmGAMYB-1/-2, GhGPAT12/25, etc., which is much less than a single GMS gene.…”

Applications of Virus-Induced Gene Silencing in Cotton

“…However, their exact role and potential regulatory mechanisms in cotton anther development are poorly understood. GhGPAT12/25 has been confirmed to regulate tapetum degradation, anther cuticle formation, and pollen wall development [ 73 ]. Further investigation showed that the expression of GhGPAT12/25 might be activated by GhMYB80s in the regulation of male fertility.…”

“…Further investigation showed that the expression of GhGPAT12/25 might be activated by GhMYB80s in the regulation of male fertility. The virus-induced gene silencing of GhMYB80s in cotton exhibited a dramatic reduction in male fertility [ 73 ]. These findings provide insights into the regulatory mechanism of cotton anther development.…”

High‐temperature stress in crops: male sterility, yield loss and potential remedy approaches

“…In recent study of Wan et al (2020), it was found that many genes are involved in the biosynthesis and transport of cutin and wax in anther wall layers; however, Glycerol-3-phosphate acyltransferases was found in many crops to have a vital role in cutin biosynthesis. For instance, in rice, the gene OsGPAT3, in cotton GhGPAT12/25, and ZmMs33/ZmGPAT6 in maize have a function in cutin biosynthesis, while its knock-out creates sterile plants containing defective pollen grains due to delayed or premature PCD (Sun et al, 2018;Zhang et al, 2021b;Zhu et al, 2020). During HT stress, the gene GPAT was suppressed (Xue et al, 2019), which affects the fatty acid pathways, displays an abnormal cuticle layer in the anther, affects pollen exine formation and leads to male sterile plants.…”