Auxin is a phytohormone that plays an important role in plant growth and development by forming local concentration gradients. The regulation of auxin levels is determined by the activity of auxin efflux carrier protein PIN-formed (PIN). In Arabidopsis thaliana, PIN-formed1 (PIN1) functions in inflorescence and root development. In rice (Oryza sativa L.), there are four PIN1 homologs (OsPIN1a-1d), but their functions remain largely unexplored. Hence, in this study, we created mutant alleles of PIN1 gene-pin1a, pin1b, pin1c, pin1d, pin1a pin1b and pin1c pin1d- using CRISPR/Cas9 technology and used them to study the functions of the four OsPIN1 paralogs in rice. In wild-type rice, all four OsPIN1 genes were relatively highly expressed in the root than in other tissues. Compared with the wild type, the OsPIN1 single mutants had no dramatic phenotypes, but the pin1a pin1b double mutant had shorter shoots and primary roots, fewer crown roots, reduced root gravitropism, longer root hairs and larger panicle branch angle. Furthermore, the pin1c pin1d double mutant showed no observable phenotype at the seedling stage, but showed naked, pin-shape inflorescence at flowering. These data suggest that OsPIN1a and OsPIN1b are involved in root, shoot and inflorescence development in rice, whereas OsPIN1c and OsPIN1d mainly function in panicle formation. Our study provides basic knowledge that will facilitate the study of auxin transport and signaling in rice.

中文翻译：

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水稻中PIN1旁系基因的功能差异。

生长素是一种植物激素，通过形成局部浓度梯度在植物生长和发育中起重要作用。生长素水平的调节取决于形成PIN的生长素外排载体蛋白的活性。在拟南芥中，PIN-formed1（PIN1）在花序和根系发育中起作用。在水稻（Oryza sativa L.）中，有四个PIN1同源物（OsPIN1a-1d），但它们的功能在很大程度上尚未得到开发。因此，在这项研究中，我们使用CRISPR / Cas9技术创建了PIN1基因-pin1a，pin1b，pin1c，pin1d，pin1a pin1b和pin1c pin1d的突变等位基因，并用它们研究了水稻中四个OsPIN1旁系同源物的功能。在野生型水稻中，所有四个OsPIN1基因在根中的表达均高于其他组织。与野生型相比，OsPIN1单突变体没有显着的表型，但是pin1a pin1b双重突变体的芽和初生根较短，冠根较少，降低了地心引力，更长的根毛和更大的圆锥花序分支角。此外，pin1c pin1d双突变体在苗期没有观察到表型，但在开花时显示出裸露的针状花序。这些数据表明OsPIN1a和OsPIN1b参与了水稻的根，茎和花序发育，而OsPIN1c和OsPIN1d主要在穗形成中起作用。我们的研究提供了基础知识，将有助于研究水稻中的植物生长素运输和信号传导。pin1c pin1d双重突变体在苗期没有表现出可观察到的表型，但在开花时显示出裸露的针状花序。这些数据表明OsPIN1a和OsPIN1b参与了水稻的根，茎和花序发育，而OsPIN1c和OsPIN1d主要在穗形成中起作用。我们的研究提供了基础知识，将有助于研究水稻中的植物生长素运输和信号传导。pin1c pin1d双重突变体在苗期没有观察到表型，但在开花时显示出裸露的针状花序。这些数据表明OsPIN1a和OsPIN1b参与了水稻的根，茎和花序发育，而OsPIN1c和OsPIN1d主要在穗形成中起作用。我们的研究提供了基础知识，将有助于研究水稻中的植物生长素运输和信号传导。