OsAP65, a rice aspartic protease, is essential for male fertility and plays a role in pollen germination and pollen tube growth

Abstract

Aspartic proteases (APs) comprise a large proteolytic enzyme family widely distributed in animals, microbes, viruses, and plants. The rice genome encodes 96 APs, of which only a few have been functionally characterized. Here, the identification and characterization of a novel AP gene, OsAP65, which plays an indispensable role in pollen tube growth in rice, is reported. The T-DNA insertion line of OsAP65 caused severe segregation distortion. In the progeny derived from an individual heterozygous for the T-DNA insertion, the wild type and T-DNA-carrying heterozygote segregated at a ratio close to 1:1, while homozygotes of disrupted OsAP65 (OsAP65–/–) were not recovered. Reciprocal crosses between heterozygotes and wild-type plants demonstrated that the mutant alleles could not be transmitted through the male gamete. Examination of the anthers from heterozygous plants revealed that the mutant pollen matured normally, but did not germinate or elongate. OsAP65 was expressed in various tissues and the transcript level in heterozygous plants was about half of the amount measured in the wild-type plants. The subcellular localization showed that OsAP65 is a pre-vacuolar compartment (PVC) protein. These results indicated that OsAP65 was essential for rice pollen germination and tube growth.

Two Membrane-Anchored Aspartic Proteases Contribute to Pollen and Ovule Development

“…Many aspartic proteases in plants have been reported to be involved in sexual reproduction (Ge et al, 2005;Chen et al, 2008;Yang et al, 2012;Huang et al, 2013;Niu et al, 2013). In this study, RT-PCR and GUS staining assays revealed that both A36 and A39 are specifically expressed in pollen grains and in growing pollen tubes (Fig.…”

Rice phenylalanine ammonia-lyase gene OsPAL4 is associated with broad spectrum disease resistance

“…6). Heterozygous mutations can result in a 50 % reduction in overall expression due to a functional single allele (Huang et al 2013), and in the ospal4 mutant, we observed a significantly lower expression level of OsPAL4 compared to the wild type (Fig. 6).…”

Tomato Male sterile 1035 is essential for pollen development and meiosis in anthers

“…Cell wall modification/degeneration genes such as proteolytic enzyme families induce PCD in tapetum cells ( Niu et al , 2013 ). Solyc06g069220.1.1 had high similarity to rice aspartic proteinase 65 , which is involved in tapetum degradation ( Huang et al , 2013 ).…”