Overexpression of Maize ZmMYB59 Gene Plays a Negative Regulatory Role in Seed Germination in Nicotiana tabacum and Oryza sativa

Abstract

MYB transcription factors are involved in many biological processes, including metabolism, stress response and plant development. In our previous work, ZmMYB59 was down-regulated by deep sowing during maize seed germination. However, there are few reports on seed germination regulated by MYB proteins. In this study, to examine its functions during seed germination, Agrobacterium-mediated transformation was exploited to generate ZmMYB59 overexpression (OE) tobacco and rice. In T 2 generation transgenic tobacco, germination rate, germination index, vigor index and hypocotyl length were significantly decreased by 25.0-50.9, 34.5-54.4, 57.5-88.3, and 21.9-31.3% compared to wild-type (WT) lines. In T 2 generation transgenic rice, above corresponding parameters were notably reduced by 39.1-53.8, 51.4-71.4, 52.5-74.0, and 28.3-41.5%, respectively. On this basis, antioxidant capacity and endogenous hormones were determined. The activities of catalase, peroxidase, superoxide dismutase, ascorbate peroxidase of OE lines were significantly lower than those of WT, suggesting that ZmMYB59 reduced their oxidation resistance. As well, ZmMYB59 overexpression extremely inhibited the synthesis of gibberellin A1 (GA 1) and cytokinin (CTK), and promoted the synthesis of abscisic acid (ABA) concurrently. Taken together, it proposed that ZmMYB59 was a negative regulator during seed germination in tobacco and rice, which also contributes to illuminate the molecular mechanisms regulated by MYB transcription factors.

Comparative Transcriptome Analysis Reveals Regulatory Networks during the Maize Ear Shank Elongation Process

“…In plants, these transcription factor families are related to hormone signaling transduction during cell elongation. It has been proven that overexpressed ZmMYB59 during seed germination promotes the synthesis of ABA and inhibits the synthesis of gibberellin and cytokines, thereby hindering cell elongation [44]. The application of exogenous brassinolide can up-regulate the expression of GhbHLH/HLH genes in cotton fiber.…”

DNA-Binding One Finger Transcription Factor PhDof28 Regulates Petal Size in Petunia

“…In contrast, overexpression of its orthologous GmMYB010 gene could not produce similar phenotypes in soybean [Glycine max (L.) Merr.]. In addition, overexpression of the maize (Zea mays L.) MYB59 TF significantly reduced the seeds' germination rates in transgenic tobacco plants [21]; however, overexpression of its orthologous OsMYBAS1 gene promoted germination of transgenic rice seeds [22]. Given these reports, it is reasonable to speculate that PhDof28 and its orthologous AtDof5.4 gene might have undergone functional differentiation during plant evolution.…”

Application of Methionine Increases the Germination Rate of Maize Seeds by Triggering Multiple Phenylpropanoid Biosynthetic Genes at Transcript Levels

“…Upstream of the GA synthesis and degradation pathway, V-myb avian myeloplastosis viral oncogene homolog (MYB) transcription factors are also involved in the regulation of maize seed germination. Maize ZmMYB59 can activate the expression of GA2Ox-3 and GA2Ox-10 encoding gibberellin 2 oxidase by binding to the ATCCACC element in plants, leading to the conversion of active GA into an inactive form, thereby reducing the endogenous GA content in plants and inhibiting maize seed germination [7]. Moreover, it is important to note that plant hormones do not only act alone; many of them also have antagonistic or synergistic effects with each other to better assist plant growth and development, such as the interaction relationship between jasmonic acid (JA), ABA, and GA. GA can affect the content of JA through RGA-LIKE 2 (RGL2), a member of the DELLA protein, a major inhibitor of Arabidopsis germination, and ABA can also promote JA synthesis through the SAPK10-bZIP72-AOC pathway.…”