Xiao Yunhua, Zhang Junwen, Yu Guiyuan, Lu Xuedan, Mei Wentao, Deng Huabing, Zhang Guilian, Chen Guihua, Chu Chengcai, Tong Hongning, Tang Wenbang
Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, College of Agriculture, Hunan Agricultural University, Changsha, China.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2020 Dec 22;11:618560. doi: 10.3389/fpls.2020.618560. eCollection 2020.
Cytokinins (CKs) are a class of phytohormones playing essential roles in various biological processes. However, the mechanisms underlying CK transport as well as its function in plant growth and development are far from being fully elucidated. Here, we characterize the function of PURINE PERMEASE1 (OsPUP1) in rice ( L.). was predominantly expressed in the root, particularly in vascular cells, and CK treatment can induce its expression. Subcellular localization analysis showed that OsPUP1 was predominantly localized to the endoplasmic reticulum (ER). Overexpression of resulted in growth defect of various aerial tissues, including decreased leaf length, plant height, grain weight, panicle length, and grain number. Hormone profiling revealed that the CK content was decreased in the shoot of -overexpressing seedling, but increased in the root, compared with the wild type. The CK content in the panicle was also decreased. Quantitative reverse transcription-PCR (qRT-PCR) analysis using several CK type-A () as the marker genes suggested that the CK response in the shoot of -overexpressing seedling is decreased compared to the wild type when CKs are applied to the root. Genetic analysis revealed that BG3/OsPUP4, a putative plasma membrane-localized CK transporter, overcomes the function of OsPUP1. We hypothesize that OsPUP1 might be involved in importing CKs into ER to unload CKs from the vascular tissues by cell-to-cell transport.
细胞分裂素（CKs）是一类在各种生物学过程中发挥重要作用的植物激素。然而，CK运输的潜在机制及其在植物生长发育中的功能远未得到充分阐明。在这里，我们描述了水稻（Oryza sativa L.）中嘌呤通透酶1（OsPUP1）的功能。OsPUP1主要在根中表达，特别是在维管细胞中，并且CK处理可以诱导其表达。亚细胞定位分析表明，OsPUP1主要定位于内质网（ER）。OsPUP1过表达导致各种地上组织生长缺陷，包括叶片长度、株高、粒重、穗长和粒数减少。激素分析表明，与野生型相比，OsPUP1过表达幼苗地上部分的CK含量降低，但根中的CK含量增加。穗中的CK含量也降低。使用几种A型CK响应调节因子（ARRs）作为标记基因的定量逆转录PCR（qRT-PCR）分析表明，当将CKs施加到根上时，OsPUP1过表达幼苗地上部分的CK响应与野生型相比降低。遗传分析表明，一种假定的质膜定位的CK转运蛋白BG3/OsPUP4克服了OsPUP1的功能。我们假设OsPUP1可能参与将CKs导入内质网，通过细胞间运输从维管组织卸载CKs。
