Speaker: Ueli Grossniklaus, professor in the Department of Plant and Microbial Biology, and Zürich-Basel Plant Science Center, University of Zürich, Switzerland

Title: "Signaling processes during plant development and reproduction"

Abstract: Research in our laboratory focuses on the developmental genetics of plant reproduction, with an emphasis on epigenetic gene regulation and cell-cell communication during double fertilization. Fertilization depends on the proper reception of the pollen tube by the synergid cells involving a complex interplay mediated by calcium signaling [1]. We have shown that receptor kinases (RKs) of the CrRLK1L subfamily play an important role in reproduction, with the FERONIA RK acting in the synergids and the two redundant ANXUR (ANX1/2) RKs in the pollen tube [2,3]. The extracellular domain of CrRLK1Ls has similarities with malectin, suggesting it may bind carbohydrate moieties, but it was also reported to bind the small, secreted RALF peptides [4,5,6]. Thus, the functions of CrRLK1Ls are diverse and complex. Upon proper reception of the pollen tube, the two sperm cells are released to effect double fertilization. How exactly fertilization triggers the development of the two fertilization products, the embryo and endosperm, is currently unknown. In this seminar, I will report on our process in deciphering the signals and underlying mechanisms that control reproduction in plants.

Host: Michelle Guo, assistant professor in the Department of Genetics, Development and Cell Biology

[1]    Ngo QA, Vogler H, Lituiev DS, Nestorova A, Grossniklaus U (2014). A calcium dialog mediated by FERONIA signal transduction controls plant sperm delivery. Dev Cell 29, 491-500.
[2]    Escobar-Restrepo JM, Huck N, Kessler S, Gagliardini V, Gheyselinck J, Yang WC, Grossniklaus U (2007). The FERONIA receptor-like kinase mediates male-female interactions during pollen tube reception. Science 317:656-660.
[3]    Boisson-Dernier AJ, Roy S, Kritsas K, Grobei MS, Jaciubek M, Schroeder JI, Grossniklaus U (2009). Disruption of the pollen-expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge. Development 136, 3279-3288.
[4]    Haruta M, Sabat G, Stecker K, Minkoff BB, Sussman MR (2014). A peptide homone and its receptor protein kinase regulate plant cell expansion. Science 343, 408-411.
[5]    Mecchia M, Santos-Fernandez G, Duss NN, Somoza SC, Boisson-Dernier A, Gagliardini V, Martínez-Bernardini A, Ndinyanka Fabrice T, Ringli C, Muschietti JP, Grossniklaus U (2017) RALF4/19 peptides interact with LRX proteins to control pollen tube growth in Arabidopsis. Science 358, 1600-1603.
[6]    Moussu S, Broyart C, Santos-Fernandez G, Augustin S, Wehrle S, Grossniklaus U, Santiago J (2020) Structural basis for recognition of RALF peptides by LRX proteins during pollen tube growth. Proc Natl Acad Sci USA 117, 7494-7503.