A novel Arabidopsis MYB-like transcription factor, MYBH, regulates hypocotyl elongation by enhancing auxin accumulation

Abstract

Critical responses to developmental or environmental stimuli are mediated by different transcription factors, including members of the ERF, bZIP, MYB, MYC, and WRKY families. Of these, MYB genes play roles in many developmental processes. The overexpression of one MYB gene, MYBH, significantly increased hypocotyl elongation in Arabidopsis thaliana plants grown in the light, and the expression of this gene increased markedly in the dark. The MYBH protein contains a conserved motif, R/KLFGV, which was implicated in transcriptional repression. Interestingly, the gibberellin biosynthesis inhibitor paclobutrazol blocked the increase in hypocotyl elongation in seedlings that overexpressed MYBH. Moreover, the function of MYBH was dependent on phytochrome-interacting factor (PIF) proteins. Taken together, these results suggest that hypocotyl elongation is regulated by a delicate and efficient mechanism in which MYBH expression is triggered by challenging environmental conditions such as darkness, leading to an increase in PIF accumulation and subsequent enhanced auxin biosynthesis. These results indicate that MYBH is one of the molecular components that regulate hypocotyl elongation in response to darkness.

Gene cloning of ZmMYB59 transcription factor in maize and its expression during seed germination in response to deep‐sowing and exogenous hormones

“…According to the report of Collett, Harberd, and Leyser (), the auxin levels in wild‐type Arabidopsis were optimal for hypocotyl extension, whereas the extension was suppressed after spraying exogenous auxin. A novel Arabidopsis MYB‐like transcription factor, MYBH, regulated hypocotyl elongation by enhancing auxin accumulation (Kwon et al., ). In our results, IAA soaking significantly promoted ZmMYB59 expression in mesocotyls while reduced its expression in roots.…”

“…GA 3 significantly enhanced the elongation of the first internode in Hong Mang Mai, a wheat variety tolerant to deep-seeding conditions (Chen et al, 2001(Chen et al, , 2003 (2000), the auxin levels in wild-type Arabidopsis were optimal for hypocotyl extension, whereas the extension was suppressed after spraying exogenous auxin. A novel Arabidopsis MYB-like transcription factor, MYBH, regulated hypocotyl elongation by enhancing auxin accumulation (Kwon et al, 2013).…”

Role of Reactive Oxygen Species during Cell Expansion in Leaves

“…In both cases, loss of the transcriptional regulators results in increased H 2 O 2 levels and decreased cell size, indicating that the biochemical action of H 2 O 2 in roots and leaves on cell enlargement is conserved. Notably, UPB1 was shown to act independently from plant hormones, while overexpression of KUA1 is accompanied by an increase in auxin (Kwon et al, 2013). As KUA1 and UPB1 show no homology, it indicates that plants evolved diverse transcriptional regulators to control POXs.…”

MYB-related transcription factors function as regulators of the circadian clock and anthocyanin biosynthesis in Arabidopsis

“…9 Additionally, MYBH/KUA1 expression is regulated by the circadian clock and this MYBH/ KUA1 transcription factor regulates cell expansion, hypocotyl elongation, and leaf senescence in the plant. [14][15][16] Currently, we have found that AtMYBD expression is also controlled by diurnal regulation, see ref. 17 , and this implies that the AtMYBD transcription factor may function to control downstream processes in a circadian clock-dependent manner.…”