Defective Pollen Wall 3 (DPW3), a novel alpha integrin‐like protein, is required for pollen wall formation in rice

Abstract

In flowering plants, pollen wall is a specialized extracellular cell-wall matrix surrounding male gametophytes and acts as a natural protector of pollen grains against various environmental and biological stresses. The formation of pollen wall is a complex but well-regulated process, which involves the action of many different genes. However, the genetic and molecular mechanisms underlying this process remain largely unknown.In this study, we isolated and characterized a novel rice male sterile mutant, defective pollen wall3 (dpw3), which displays smaller and paler anthers with aborted pollen grains. DPW3 encodes a novel membrane-associated alpha integrin-like protein conserved in land plants. DPW3 is ubiquitously expressed in anther developmental stages and its protein is localized to the plasma membrane, endoplasmic reticulum (ER) and Golgi.Anthers of dpw3 plants exhibited unbalanced anther cuticular profile, abnormal Ubisch bodies, disrupted callose deposition, defective pollen wall formation such as abnormal microspore plasma membrane undulation and defective primexine formation, resulting in pollen abortion and complete male sterility.Our findings revealed a novel and vital role of alpha integrin-like proteins in plant male reproduction.

A Silent Exonic Mutation in a Rice Integrin-α FG-GAP Repeat-Containing Gene Causes Male-Sterility by Affecting mRNA Splicing

“…Indeed, in pl1, the transcript levels of several key enzyme encoding genes involved in this process were down-regulated ( Figure 8A-D). Consistently, loss-of-function of PL1 decreased the levels of serval waxes components and dominant cutin monomers [52]. These data raise a possibility that PL1 might participate in male development by affecting the metabolic pathway of anther cuticle and pollen exine.…”

“…Similar to defective pollen wall 3 (dpw3), another allelic mutant of pl1 (in japonica background) reported very recently [52], our pl1 mutant (in indica background) exhibited slightly swollen tapetum and abnormal primexine matrix formation at stage 9 ( Figures 6H and 7N), and necrosis-like tapetum cell death with less cytoplasmic contents, severely enlarged cell size and compromised cell wall integrity, as well as defective formation of Ubisch bodies and anther cuticle at later stages ( Figure 6L-O and Figure 7P,R,T). However, pl1 had some characteristics distinguished from dpw3.…”

“…Together, these results confirmed that the mutation in Os02g01070 is responsible for the defective male-fertility in pl1. In another parallel study, other mutations in Os02g01070, which was named as Defective Pollen Wall 3 (DPW3), were also identified and consistently lead to the similar male-sterile phenotype [52].…”

Male sterile 305 Mutation Leads the Misregulation of Anther Cuticle Formation by Disrupting Lipid Metabolism in Maize

“…The main lipid precursors of sporopollenin include linear fatty acids and monomers of oxygen-containing aromatic compounds, such as coumarin (C9) and ferulic acid (C10), all of which are synthesized in the tapetum cells [26]. In recent years, many genes that are involved in fatty acid metabolism and mediating anther cuticle and sporopollenin formation, whose mutation often leads to male sterile in Arabidopsis thaliana, rice and maize have been reported [19,29,30]. In addition, phospholipase a (releases lysophospholipids) and lipoxygenase (catalyses fatty acid oxidation) were involved in regulating pollen germination in olive (Olea europaea L.) [31].…”

Deficiencies in the formation and regulation of anther cuticle and tryphine contribute to male sterility in cotton PGMS line

“…However, some evidences demonstrates that carotenoids, avonoids, isoprenoids (terpenoids) and sterol esters are also precursors for the anther cuticle formation [9,10]. Several TTP-speci c genes have been showed to be essential to the early formation of anther cuticle and pollen exine, such as DPW, DPW2, OsGPAT3, DWP3, OsNP1, CYP704B2 and CYP703A3 in rice [11][12][13][14][15][16][17]. In plants, the CER family, also known as the Glossy (GL) family, have been reported to be involve in the accumulation of epicuticular waxes.…”