Ishikawa Motokazu, Ohmori Yoshihiro, Tanaka Wakana, Hirabayashi Chizuru, Murai Koji, Ogihara Yasunari, Yamaguchi Takahiro, Hirano Hiro-Yuki
Graduate School of Agricultural Life Sciences, The University of Tokyo, Bunkyu-ku, Tokyo, Japan.
Genes Genet Syst. 2009 Apr;84(2):137-46. doi: 10.1266/ggs.84.137.
The DROOPING LEAF (DL) gene regulates carpel specification in the flower and midrib formation in the leaf in Oryza sativa (rice). Loss-of-function mutations in the dl locus cause homeotic transformation of carpels into stamens and lack of midrib, resulting in the drooping leaf phenotype. DL is a member of the YABBY gene family and is closely related to the CRABS CLAW (CRC) gene in Arabidopsis thaliana. The function of Arabidopsis CRC, however, differs from that of rice DL: it is responsible for nectary development and is partially involved in carpel identity. Thus, genes related to DL/CRC seem to have functionally diversified during angiosperm evolution. To assess the conservation of DL function in related species, here we examined the in situ expression patterns of DL orthologs in three grass species, i.e., maize, wheat and sorghum, which is assigned to subfamilies different from Ehrhartoideae including O. sativa. The results clearly show that the temporal and spatial expression patterns of DL orthologs in the three species are identical to those of rice DL in both flower and leaf development, suggesting that DL-related genes are functionally conserved within the grass family. It is likely that DL may have been recruited to carpel specification and midrib formation within the lineage of the grass family after divergence of their ancestor from that of eudicots.
下垂叶（DL）基因调控水稻（Oryza sativa）花中的心皮特化和叶中脉的形成。dl位点的功能缺失突变导致心皮同源异型转化为雄蕊且缺乏中脉，从而产生下垂叶表型。DL是YABBY基因家族的成员，与拟南芥中的蟹爪（CRC）基因密切相关。然而，拟南芥CRC的功能与水稻DL的功能不同：它负责蜜腺发育，并部分参与心皮身份的确定。因此，与DL/CRC相关的基因在被子植物进化过程中似乎在功能上发生了分化。为了评估DL功能在相关物种中的保守性，我们在此研究了三种禾本科植物（即玉米、小麦和高粱）中DL直系同源基因的原位表达模式，这三种植物属于与包括水稻在内的稻亚科不同的亚科。结果清楚地表明，这三个物种中DL直系同源基因在花和叶发育过程中的时空表达模式与水稻DL的相同，这表明与DL相关的基因在禾本科内功能保守。在禾本科祖先与双子叶植物祖先分化之后，DL可能在禾本科谱系中被用于心皮特化和中脉形成。
