Comprehensive Analysis of Arabinogalactan Protein-Encoding Genes Reveals the Involvement of Three BrFLA Genes in Pollen Germination in Brassica rapa

• Published in: International journal of molecular sciences Vol. 22; no. 23; p. 13142
• Main Authors: Huang, Huiting, Miao, Yingjing, Zhang, Yuting, Huang, Li, Cao, Jiashu, Lin, Sue
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 05.12.2021; MDPI
• Subjects: AGP gene; Amino acids; Annotations; Anthers; Arabinogalactan; arabinogalactan protein (AGP); Brassica rapa; Brassica rapa - genetics; Brassica rapa - physiology; Carbohydrates; Chinese cabbage; Chinese cabbage (Brassica rapa ssp. chinensis); Cloning, Molecular; Evolution, Molecular; Extensin; fasciclin-like AGP (FLA); Gene duplication; Gene Expression Profiling - methods; Gene Expression Regulation, Plant; Genes; Genomes; Germination; Glycoproteins; Hybrids; Hydroxyproline; Lysine; male sterility; Mucoproteins - genetics; Peptides; Phylogeny; Plant Infertility; Plant Proteins - genetics; Pollen; pollen germination; Pollen tubes; Proteins; Reagents; Relative humidity; Sequence Analysis, RNA; Signal transduction; arabinogalactan protein (AGP); pollen germination; fasciclin-like AGP (FLA); male sterility; Chinese cabbage (Brassica rapa ssp. chinensis)
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms222313142

Arabinogalactan proteins (AGPs) are a superfamily of hydroxyproline-rich glycoproteins that are massively glycosylated, widely implicated in plant growth and development. No comprehensive analysis of the gene family has been performed in Chinese cabbage ( ssp. ). Here, we identified a total of 293 putative AGP-encoding genes in , including 25 classical AGPs, three lysine-rich AGPs, 30 AG-peptides, 36 fasciclin-like AGPs (FLAs), 59 phytocyanin-like AGPs, 33 xylogen-like AGPs, 102 other chimeric AGPs, two non-classical AGPs and three AGP/extensin hybrids. Their protein structures, phylogenetic relationships, chromosomal location and gene duplication status were comprehensively analyzed. Based on RNA sequencing data, we found that 73 genes were differentially expressed in the floral buds of the sterile and fertile plants at least at one developmental stage in , suggesting a potential role of AGPs in male reproductive development. We further characterized , and , three FLA members especially expressed in anthers, pollen grains and pollen tubes. , and are indispensable for the proper timing of pollen germination under high relative humidity. Our study greatly extends the repertoire of AGPs in and reveals a role for three members of the FLA subfamily in pollen germination.