Loss of Arabidopsis PATATIN-RELATED PHOSPHOLIPASE 2A Affects the Expression of Genes Involved in Fertilization

Doubled haploid (DH) technology enables the generation and evaluation of new plant genotypes in ≤ 2 years, which is in stark contrast to the 6-7 years required for conventional breeding. Recently, a few proteins including MATRILINEAL (MTL) were found to trigger haploid induction in monocot plants. However, MTL function in dicot plants remains unclear. Here, we investigate the effects of Arabidopsis PATATIN-RELATED PHOSPHOLIPASE 2A (pPLA-IIα), a maize MTL homolog, on the expression of genes that modulate pollen development and fertilization in Arabidopsis. Quantitative real-time PCR analysis showed that transcript levels of four pollen tube growth-related genes and six pollen guidance- or reception-related genes were increased in the ppla-iiα T-DNA insertion mutant compared with the wild type. In addition, transcript levels of four mitosis- and meiosis-related genes, two hormone-related genes, and a calcium pump-encoding gene were also upregulated in the ppla-iiα mutant, whereas expression levels of genes encoding a synergid-secreted peptide (AtLURE1.1) and calmodulin-activated Ca²⁺ -ATPase ion pump 9 (ACA9) protein were downregulated in the ppla-iiα mutant compared with the wild type. Taken together, these results suggest that AtLURE1.1 and ACA9 play positive roles in pPLA-IIα-mediated fertilization. Thus, pPLA-IIα controls fertilization through the modulation of pollen germination and pollen tube growth and guidance in Arabidopsis.