The emerging role of cysteine-rich peptides in pollen-pistil interaction.

Abstract

Unlike early land plants, flowering plants have evolved a pollen tube that transport a pair of non-motile sperm cells to the female gametophyte. This process, known as siphonogamy, was first observed in gymnosperms and later become prevalent in angiosperms. However, the precise molecular mechanisms underlying the male-female interactions remain enigmatic. From the pollen grain's landing on the stigma to gametes fusion, the male part needs to pass various tests: How does the stigma distinguish between compatible and incompatible pollen? What mechanisms guide pollen tube towards the ovule? What factors trigger pollen tube rupture? How is polyspermy prevented? And how does the sperm cell ultimately reach the egg? Successful male-female communications is essential for surmounting these challenges, with cysteine-rich peptides (CRPs) playing a pivotal role in these dialogues. In this review, we summarize the characteristics of four distinct classes of CRPs and then we systematically review the recent progresses of the role of CRPs in four crucial stages of pollination and fertilization. Finally, we conclude by considering the potential applications of this knowledge in crop breeding, and suggesting avenues for future research.