Integrated analysis of pollen recognition and double fertilization mechanisms

Brown University, Providence RI

Investigators

Abstract

Fertilization and seed production in flowering plants relies on the delivery of two sperm to female gametes by a pollen tube. The success of the long and rapid journey of the pollen tube relies on constant signaling between the pollen tube cell and the cells of the pistil. Pollen tubes must find specific cellular targets, they must burst when they arrive at the target, and their sperm must fuse with female gametes. These events are all essential for seed production, which is central to agricultural production and food security. Our goal is to understand the molecules that mediate exchanges between pollen and pistil. Cellular interactions between pollen and pistil are mediated by extracellular signaling exchanges occurring in a complex environment where multiple pollen tubes are competing for a limited number of ovules. Ovules are the structures where female gametes develop and that mature into seeds (e.g. rice grains and corn kernels) only after successful fertilization by a pollen tube. The United States will be better able to contribute to scientific progress when our scientists represent the full diversity of our nation. This project will provide cutting edge training in biological imaging, genetics and genomics for early-stage students from groups that have not traditionally been represented in US science. These students will join a team of graduate students and a post-doctoral researcher who will also receive training through this project. This project will use unique molecular tools to define: 1) Pollen components of the signaling system that results in cessation of tube growth and sperm release in the ovule, 2) Novel components of the mechanisms required for gamete fusion, and 3) How gamete fusion triggers a mechanism that prevents multiple pollen tubes from entering a single ovule.This project will take an integrated approach to the study of fertilization in flowering plants. The molecules that must be displayed by the pollen tube for recognition by the female will be discovered. The project will also define novel components of the gamete fusion mechanism and test hypotheses aimed at understanding how gamete fusion blocks attraction of subsequent pollen tubes. The project takes advantage of unique expertise in imaging, genetics, and genomics to understand how pollen-pistil interactions are integrated to maximize seed production. Defining the molecular exchanges between pollen and pistil that maximize reproductive success will transform our ability to generate new crop varieties with resilient pollination systems.