National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
J Exp Bot. 2013 Aug;64(11):3351-60. doi: 10.1093/jxb/ert173.
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.
天冬氨酸蛋白酶（APs）是广泛存在于动物、微生物、病毒和植物中的一大类蛋白水解酶。水稻基因组编码 96 种 APs，其中只有少数几种具有功能特征。本文报道了一种新的 AP 基因 OsAP65 的鉴定和特征，该基因在水稻花粉管生长中起着不可或缺的作用。OsAP65 的 T-DNA 插入系导致严重的分离失真。在 T-DNA 插入个体的后代中，野生型和 T-DNA 携带的杂合子以接近 1:1 的比例分离，而破坏的 OsAP65（OsAP65-/-）的纯合子则没有恢复。杂合子与野生型植物之间的正反交表明，突变等位基因不能通过雄配子传递。对杂合子花药的检查表明，突变花粉成熟正常，但不能萌发或伸长。OsAP65 在各种组织中表达，杂合子中的转录水平约为野生型植物的一半。亚细胞定位表明 OsAP65 是前液泡区室（PVC）蛋白。这些结果表明 OsAP65 对水稻花粉萌发和管生长是必需的。
