The architecture of the panicle, including grain size and panicle morphology, directly determines grain yield. Panicle erectness, which is selected for achieving ideal plant architecture in the northern part of China, has drawn increasing attention of rice breeders. Here, dense and erect panicle 2 (dep2) mutant, which shows a dense and erect panicle phenotype, was identified. DEP2 encodes a plant-specific protein without any known functional domain. Expression profiling of DEP2 revealed that it is highly expressed in young tissues, with most abundance in young panicles. Morphological and expression analysis indicated that mutation in DEP2 mainly affects the rapid elongation of rachis and primary and secondary branches, but does not impair the initiation or formation of panicle primordia. Further analysis suggests that decrease of panicle length in dep2 is caused by a defect in cell proliferation during the exponential elongation of panicle. Despite a more compact plant type in the dep2 mutant, no significant alteration in grain production was found between wild type and dep2 mutant. Therefore, the study of DEP2 not only strengthens our understanding of the molecular genetic basis of panicle architecture but also has important implications for rice breeding.
穗的構(gòu)成包括籽粒大小和穗的形態(tài)，二者直接決定最終的產(chǎn)量。直立穗作為中國北方水稻理想株型的重要性狀已受到越來越多育種家的重視，dep2 是一個新的直立密穗突變體。DEP2 編碼一個目前功能未知的植物特有蛋白，主要在幼嫩組織（尤其幼穗）中表達。形態(tài)和表達分析表明DEP2 主要影響穗軸和一二次枝梗的伸長，但并不減弱穗原基的初始和形成。進一步分析表明，dep2 的穗長減少是因為在穗指數(shù)生長時細胞增殖減少所致。盡管dep2 植株具有更加緊湊的株型，但并未其與野生型之間有顯著的產(chǎn)量差異。因此，對DEP2 的研究不僅增加我們對穗發(fā)育的了解，而且在水稻育種中有著重要的應用價值。