The journey to glory: receptor-like kinases in pollen tube growth

Glycosylphosphatidylinositol-anchored proteins mediate the interactions between pollen/pollen tube and pistil tissues

In flowering plants, pollen germination on the stigma and pollen tube growth in pistil tissues are critical for sexual plant reproduction, which are involved in the interactions between pollen/pollen tube and pistil tissues. GPI-anchored proteins (GPI-APs) are located on the external surface of the plasma membrane and function in various processes of sexual plant reproduction. The evidences suggest that GPI-APs participate in endosome machinery, Ca²⁺ oscillations, the development of the transmitting tract, the maintenance of the integrity of pollen tube, the enhancement of interactions of the receptor-like kinase (RLK) and ligand, and guidance of the growth of pollen tube, and so on. In this review, we will summarize the recent progress on the roles of GPI-APs in the interactions between pollen/pollen tube and pistil tissues during pollination, such as pollen germination on the stigma, pollen tube growth in the transmitting tract, pollen tube guidance to the ovule, and pollen tube reception in the embryo sac. We will also discuss the future outlook of GPI-APs in the interactions between pollen/pollen tube and pistil tissues.

TMT-Based Quantitative Proteomic Analysis Reveals the Crucial Biological Pathways Involved in Self-Incompatibility Responses in Camellia oleifera

Camellia oleifera is a valuable woody oil plant belonging to the Theaceae, Camellia oil extracted from the seed is an excellent edible oil source. Self-incompatibility (SI) in C. oleifera results in low fruit set, and our knowledge about the mechanism remains limited. In the present study, the Tandem mass tag (TMT) based quantitative proteomics was employed to analyze the dynamic change of proteins response to self- and cross-pollinated in C. oleifera. A total of 6,616 quantified proteins were detected, and differentially abundant proteins (DAPs) analysis identified a large number of proteins. Combined analysis of differentially expressed genes (DEGs) and DAPs of self- and cross-pollinated pistils based on transcriptome and proteome data revealed that several candidate genes or proteins involved in SI of C. oleifera, including polygalacturonase inhibitor, UDP-glycosyltransferase 92A1-like, beta-D-galactosidase, S-adenosylmethionine synthetase, xyloglucan endotransglucosylase/hydrolase, ABC transporter G family member 36-like, and flavonol synthase. Venn diagram analysis identified 11 proteins that may participate in pollen tube growth in C. oleifera. Our data also revealed that the abundance of proteins related to peroxisome was altered in responses to SI in C. oleifera. Moreover, the pathway of lipid metabolism-related, flavonoid biosynthesis and splicesome were reduced in self-pollinated pistils by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In summary, the results of the present study lay the foundation for learning the regulatory mechanism underlying SI responses as well as provides valuable protein resources for the construction of self-compatibility C. oleifera through genetic engineering in the future.

Molecular Basis of Pollen Germination in Cereals

Understanding the molecular basis of pollen germination in cereals holds great potential to improve yield. Pollen, a highly specialized haploid male gametophyte, transports sperm cells through a pollen tube to the female ovule for fertilization, directly determining grain yield in cereal crops. Although insights into the regulation of pollen germination and gamete interaction have advanced rapidly in the model Arabidopsis thaliana (arabidopsis), the molecular mechanisms in monocot cereals remain largely unknown. Recently, pollen-specific genome-wide and mutant analyses in rice and maize have extended our understanding of monocot regulatory components. We highlight conserved and diverse mechanisms underlying pollen hydration, germination, and tube growth in cereals that provide ideas for translating this research from arabidopsis. Recent developments in gene-editing systems may facilitate further functional genetic research.