A loss-of-function mutation in the DWARF4/PETANKO5 gene enhances the late-flowering and semi-dwarf phenotypes of the Arabidopsis clock mutant lhy-12;cca1-101 under continuous light without affecting FLC expression

作者：Suzuki Syunji; Miyata Kana; Hara Miyuki; Niinuma Kanae; Tsukaya Hirokazu; Takase Masahide; Hayama Ryosuke; Mizoguchi Tsuyoshi^*

来源：Plant Biotechnology, 2016, 33(4): 315-321.

DOI：10.5511/plantbiotechnology.16.0601a

• brassinosteroid
• CCA1
• DWF4
• flowering time
• LHY

The circadian clock plays important roles in the control of photoperiodic flowering in Arabidopsis. Mutations in the LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) genes (lhy;cca1) accelerate flowering under short days, whereas lhy; cca1 delays flowering under continuous light (LL). The lhy; cca1 mutant also exhibits short hypocotyls and petioles under LL. However, the molecular mechanisms underlying the regulation of both flowering time and organ lengths in the LHY/CCA1-dependent pathway are not fully understood. To address these questions, we performed EMS mutagenesis of the lhy-12;cca1-101 line and screened for mutations that enhance the lhy; cca1 phenotypes under LL. In this screen, we identified a novel allele of dwarf4 (dwf4) and named it petanko 5 (pta5). A similar level of enhancement of the delay in flowering was observed in these two dwf4 mutants when combined with the lhy; cca1 mutations. The lhy; cca1 and dwf4 mutations did not significantly affect the expression level of the floral repressor gene FLC under LL. Our results suggest that a defect in brassinosteroid (BR) signaling delayed flowering independent of the FLC expression level, at least in plants with the lhy; cca1 mutation grown under LL. The dwf4/pta5 mutation did not enhance the late-flowering phenotype of plants overexpressing SVP under LL, suggesting that SVP and BR function in a common pathway that controls flowering time. Our results suggest that the lhy;cca1 mutant exhibits delayed flowering due to both the BR signaling-dependent and -independent pathways under LL.

• 出版日期2016-9