Role of Lipid Metabolism in Plant Pollen Exine Development

Abstract

Pollen plays important roles in the life cycle of angiosperms plants. It acts as not only a biological protector of male sperms but also a communicator between the male and the female reproductive organs, facilitating pollination and fertilization. Pollen is produced within the anther, and covered by the specialized outer envelope, pollen wall. Although the morphology of pollen varies among different plant species, the pollen wall is mainly comprised of three layers: the pollen coat, the outer exine layer, and the inner intine layer. Except the intine layer, the other two layers are basically of lipidic nature. Particularly, the outer pollen wall layer, the exine, is a highly resistant biopolymer of phenylpropanoid and lipidic monomers covalently coupled by ether and ester linkages. The precise molecular mechanisms underlying pollen coat formation and exine patterning remain largely elusive. Herein, we summarize the current genetic, phenotypic and biochemical studies regarding to the pollen exine development and underlying molecular regulatory mechanisms mainly obtained from monocot rice (Oryza sativa) and dicot Arabidopsis thaliana, aiming to extend our understandings of plant male reproductive biology. Genes, enzymes/proteins and regulatory factors that appear to play conserved and diversified roles in lipid biosynthesis, transportation and modification during pollen exine formation, were highlighted.

Overexpression of the TaSHN1 transcription factor in bread wheat leads to leaf surface modifications, improved drought tolerance, and no yield penalty under controlled growth conditions

“…In concert with stomata, the cuticle acts as an interface between plants and their surrounding environment, protecting them against a variety of biotic and abiotic stresses (Chen et al, ; Reina‐Pinto & Yephremov, ; Yeats & Rose, ). The cuticle also plays an essential role in plant development during pollen maturation (Shi, Cui, Yang, Kim, & Zhang, ; Zhang, Yang, & Shi, ) and in preventing organ fusion during seedling development (Kurdyukov et al, ; La Rocca et al, ; Luo, Xue, Hu, Wang, & Chen, ). However, the most important function of the cuticle is to protect aerial plant tissues and organs against water loss (Aharoni et al, ; Borisjuk, Hrmova, & Lopato, ; Yeats & Rose, ).…”

Pollen wall degradation in the Brassicaceae permits cell emergence after pollination

“…Sporopollenin's chemical resistance makes it both worthy of, and difficult to, study. Hundreds of research articles have been published in the past century seeking to characterize sporopollenin's biochemical composition developmentally (Ariizumi and Toriyama, 2011; Dobritsa et al, 2011; Quilichini et al, 2015; Zhang et al, 2016), or by extraction (Southworth, 1974), tracers, or solid‐state methods (Domínguez et al, 1999; Guilford et al, 1988; Jardine et al, 2015).…”

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

“…Lipids, categorized into eight groups (fatty acyls, glycerolipids, gly-cerophospholipids, sphingolipids, sterol lipids, prenollipids, saccharolipids, and polyketides) [25], play an important role in the development of maize anthers [26,27]. The anther cuticle is a derivative of fatty acids, which is synthesized in the endoplasmic reticulum of tapetum and distributed in the epidermis of anther to protect it from hydration [26]. Sporopollenin, a biopolymer that consists of lipid monomers, is a major component of pollen exine [28].…”