PbGLR3.3 Regulates Pollen Tube Growth in the Mediation of Ca2+ Influx in Pyrus bretschneideri

Abstract

Glutamate receptors (GluRs) are sensors of extracellular signals; they play important roles in the regulation of multiple physiological and developmental processes in eukaryotes. However, their functional roles in fruit trees are largely unknown. Here, based on the pear genome database, which was established in this lab, we identified 34 PbGLRs in pear (Pyrus bretschneideri Rehd), and they were divided into four groups by phylogenetic analysis. In comparisons with other groups, phylogenetic analyses and structural information of the PbGLRs in group 3 suggest that these genes underlie specific characteristics. Among the ten genes in group 3, we observed that the expression of PbGLR3.3 increased gradually during pollen germination and continuous growth, indicating that this gene might play a vital role in the development of pear pollen tubes. Using a combination of antisense oligodeoxy nucleotides and Ca2+-sensitive fluorescent probe methods, we verified that PbGLR3.3 participates in DSer-elicited intracellular Ca2+ signaling and Ca2+ regulation of growth in pear pollen tubes.