A small-RNA pathway that regulate male fertility under heat stress in grasses

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Unlike in animals, plants become extremely vulnerable during sexual reproduction as they undergo genetic reduction (meiosis) and large-scale developmental and whole-genome reprogramming to produce specialized haploid gametes (e.g. male sperm cells and female egg cells). Due to their sessile nature, plants are thought to have evolved coping mechanisms to be able to withstand fluctuations in ambient temperature during these critical times, however, the molecular details of such mechanisms are far from clear. We recently uncovered the presence of a novel class of small RNAs (Hphasi) acting with specific Argonaute proteins found exclusively in male germ cells and their surrounding somatic cells to regulate male fertility during heat stress conditions. We also have various lines of evidence suggesting that this pathway is conserved in the grasses. In this proposal, we therefore propose to use maize as a model crop system to determine exactly how this sRNA pathway regulates male fertility under environmental constrains, by using a variety of experimental approaches (eg. developmental genetics, biochemical, and molecular techniques) to uncover the various components and regulatory factors involved. We anticipate that this work will not only advance our basic understanding of how cereal plants safeguard their male germline but will also provide important know-how to engineer new breeding tools in cereal crops to make them more resilient to temperature stress brought on by climate change.