National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070, China.
J Integr Plant Biol. 2013 Nov;55(11):1119-35. doi: 10.1111/jipb.12101. Epub 2013 Oct 23.
In this study, PUP-type cytokinin transporter genes were identified in rice (Oryza sativa L.). The Oryza sativa purine permease (OsPUP) family has 12 members that show similar predicted protein sequences with AtPUPs. To reveal the functions of OsPUP genes, we searched the T-DNA mutant library of rice and found one mutant for the member OsPUP7. The T-DNA insertion caused a new transcript that encodes a protein with 26 amino acids different from the native OsPUP7 at the C-terminus. The mutant showed multiple phenotypic changes including increased plant height, big seeds, and delayed flowering. The mutant also showed increased sensitivity to drought and salt stresses and treatments with kinetin and abscisic acid. OsPUP7 is expressed mainly in the vascular bundle, pistil, and stamens. The measurement of cytokinins (CKs) showed that CK content in the mutant spikelets accumulated higher than that in the wild type. Moreover, uptake experiment in the yeast fcy2 mutant suggested that OsPUP7 has the ability to transport caffeine, a CK derivative. Our results indicate that the PUP transport system also exists in rice, and OsPUP7 has an important role in the transport of CK, thus affecting developmental process and stress responses.
在这项研究中，鉴定了水稻（Oryza sativa L.）中的 PUP 型细胞分裂素转运体基因。水稻嘌呤通透酶（OsPUP）家族有 12 个成员，它们与 AtPUPs 具有相似的预测蛋白序列。为了揭示 OsPUP 基因的功能，我们搜索了水稻的 T-DNA 突变体文库，发现了一个 OsPUP7 的突变体。T-DNA 插入导致一个新的转录本，该转录本在 C 末端编码的蛋白质与天然 OsPUP7 有 26 个氨基酸不同。该突变体表现出多种表型变化，包括株高增加、种子变大和开花延迟。该突变体还表现出对干旱和盐胁迫以及细胞分裂素和脱落酸处理的敏感性增加。OsPUP7 主要在维管束、雌蕊和雄蕊中表达。细胞分裂素（CKs）的测量表明，突变体小穗中的 CK 含量比野生型积累得更高。此外，在酵母 fcy2 突变体中的摄取实验表明，OsPUP7 具有运输咖啡因（一种 CK 衍生物）的能力。我们的结果表明，PUP 转运系统也存在于水稻中，OsPUP7 在 CK 的转运中起重要作用，从而影响发育过程和应激反应。
