Aims

R₂R₃-type MYB transcription factors are associated with diverse developmental processes and responses to abiotic stresses. However, there is limited information regarding drought-responsive R₂R₃-MYB in a widespread subtropical tree species, Schima superba. Hence, the purpose of this study was to identify and functionally characterize the role of SsMYB113 in S. superba under drought stress.

Results

SsMYB113, a novel R₂R₃-MYB transcription factor that was targeted to the nucleus in Arabidopsis thaliana protoplasts, functioned as a transcriptional activator during in vitro and in vivo assays. SsMYB113 transcript was abundant in the leaves of six-month-old S. superba, and was significantly up-regulated by PEG-simulated drought stress and abscisic acid (ABA). Overexpression of SsMYB113 in A. thaliana seedlings led to enhanced tolerance to drought stress and facilitated flavonoid biosynthesis and ABA accumulation, including of corresponding biosynthetic genes, particularly SsCHS and SsNCED. Furthermore, SsMYB113 was shown to bind directly to the promoters of SsCHS and SsNCED using Y1H and a dual-LUC assay, thus activating their expression. In addition, in SsMYB113-overexpressing lines, proline, water content, superoxide dismutase, and peroxidase activities increased, while malondialdehyde, electrolyte leakage, and the rate of superoxide production decreased, suggesting the explicit role of SsMYB113 in conferring drought tolerance.

Conclusions

Drought-responsive SsMYB113 functioned as a positive regulator by participating in flavonoid and ABA biosynthesis, thereby enhancing drought stress tolerance in indigenous fast-growing S. superba.

中文翻译：

---

SsMYB113 是一种木荷 MYB 转录因子，通过调节 ROS 生成来调节黄酮类化合物的积累和干旱胁迫耐受性功能

目标

R ₂ R ₃型MYB转录因子与多种发育过程和对非生物胁迫的反应有关。然而，关于在广泛分布的亚热带树种Schima superba中响应干旱的 R ₂ R ₃ -MYB 的信息有限。因此，本研究的目的是鉴定 SsMYB113 在干旱胁迫下SsMYB113 在S.superba中的作用并对其进行功能表征。

结果

SsMYB113 是一种新的 R ₂ R ₃ -MYB 转录因子，靶向拟南芥原生质体的细胞核，在体外和体内试验中充当转录激活剂。SsMYB113转录物在 6 个月大的 S.superba 叶片中含量丰富，并且在 PEG 模拟干旱胁迫和脱落酸 (ABA) 的作用下显着上调。SsMYB113在拟南芥幼苗中的过表达导致增强对干旱胁迫的耐受性并促进黄酮类生物合成和 ABA 积累，包括相应的生物合成基因，特别是SsCHS和SsNCED. 此外，使用 Y1H 和双 LUC 测定显示 SsMYB113 直接与SsCHS和SsNCED的启动子结合，从而激活它们的表达。此外，在过表达 SsMYB113的品系中，脯氨酸、水含量、超氧化物歧化酶和过氧化物酶活性增加，而丙二醛、电解质泄漏和超氧化物产生率下降，表明 SsMYB113 在赋予干旱耐受性方面的明确作用。

结论

干旱响应性 SsMYB113 通过参与类黄酮和 ABA 生物合成发挥正调节作用，从而增强本土快速生长的 S.superba 的干旱胁迫耐受性。