ANXUR1 and 2, Sister Genes to FERONIA/SIRENE, Are Male Factors for Coordinated Fertilization

Abstract

In sexual reproduction, proper communication and cooperation between male and female organs and tissues are essential for male and female gametes to unite. In flowering plants, female sporophytic tissues and gametophytes direct a male pollen tube toward an egg apparatus, which consists of an egg cell and two synergid cells. The cell-cell communication between the pollen tube and the egg apparatus makes the tip of pollen tube rupture to release the sperm cell. To detect male factors involved in this communication, we screened mutants of receptor-like kinases expressed in pollen tubes and characterized ANXUR1 (ANX1) and ANXUR2 (ANX2) genes. Here we report that pollen tubes of anx1/anx2 mutants ruptured before arriving at the egg apparatus, suggesting that ANX1 and ANX2 are male factors controlling pollen tube behavior by directing rupture at proper timing. Furthermore, ANX1 and ANX2 were the most closely related paralogs of a female factor, FERONIA/SIRENE, controlling pollen tube behavior expressed in synergid cells. Our findings show that the coordinated behaviors of female and male reproductive apparatuses are regulated by these sister genes, whose duplication might play a role in the evolution of the fertilization system in flowering plants.

Receptor-like cytoplasmic kinase MARIS functions downstream of Cr RLK1L-dependent signaling during tip growth

“…For the fast-growing PTs, this growth cessation would lead to a failure in fertilization, necessitating a robust signal transduction network to maintain CW integrity during tip growth. The ANX1/2 RLKs of the CrRLK1L subfamily and their closest homolog FER have been implicated in the control of tip growth in PTs and root hairs, respectively, acting upstream of ROSproducing NADPH oxidases (3,4,19). In this study, we identified MRI, a novel, positive downstream component of these RLK signaling pathways.…”

“…In PTs of the model plant Arabidopsis thaliana, the plasma membrane-localized ANXUR (ANX1 and ANX2) receptor-like kinases (RLKs) play a major role in controlling CW integrity and growth. On one hand, loss of function of the redundant RLKs ANX1 and ANX2 leads to precocious PT rupture shortly after germination, resulting in male sterility (3,4). This phenotype also is seen when the ANX-RLKs are degraded by the endoplasmic reticulumassociated degradation pathway in the turan mutant affecting N-glycosylation (5).…”

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana

“…Interaction of another related RLK, At2g23200 in yeast two-hybrid assays with the Pseudomonas syringae effector AvrPto showed that its expression was regulated by a number of PAMPs, pathogen-secreted molecules that regulate infection and triggers immunity (Xiang et al 2008). ANXUR 1 and ANXUR 2 which are RLKs help in cell wall integrity and are homologous to FeR, but have opposite functions to FeR (Boisson-Dernier et al 2009;Miyazaki et al 2009). These studies imply a dynamic signaling complex involving FeR and ANXUR.…”

RLKs orchestrate the signaling in plant male-female interaction

“…The CrRLK1L family is conserved in plants and consists of 17 members in Arabidopsis. ANXs are expressed in pollen tubes and loss-of-function of both ANX1 and ANX2 causes precocious pollen tube burst when grown in vitro or in the pistil (Boisson-Dernier et al, 2009;Miyazaki et al, 2009). …”