College of Horticulture and Landscape Architecture, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Northeast Agricultural University, Harbin, 150030, China.
Department of Applied Chemistry, College of Science, Northeast Agricultural University, Harbin, 150030, China.
BMC Plant Biol. 2018 Jan 18;18(1):16. doi: 10.1186/s12870-018-1236-2.
Cucumber downy mildew is among the most important diseases that can disrupt cucumber production. Propamocarb, also known as propyl-[3-(dimethylamino)propyl]carbamate (PM), is a systemic carbamate fungicide pesticide that is widely applied in agricultural production because of its high efficiency of pathogens control, especially cucumber downy mildew. However, residual PM can remain in cucumbers after the disease has been controlled. To explore the molecular mechanisms of PM retention, cucumber cultivars 'D9320' (with the highest residual PM content) and 'D0351' (lowest residual PM content) were studied. High-throughput tag-sequencing (Tag-Seq) results showed that the CsDIR16 gene was related to PM residue, which was verified using transgenic technology.
We investigated the activity of a dirigent cucumber protein encoded by the CsDIR16 in gene response to stress induced by PM treatment. Gene-expression levels of CsDIR16 were up-regulated in the fruits, leaves, and stems of 'D0351' plants in response to PM treatment. However, in cultivar 'D9320', CsDIR16 levels were down-regulated in the leaves and stems after PM treatment, with no statistically significant differences observed in the fruits. Induction by jasmonic acid, abscisic acid, polyethylene glycol 4000, NaCl, and Corynespora cassiicola Wei (Cor) resulted in CsDIR16 up-regulation in 'D0351' and 'D9320'. Expression after salicylic acid treatment was up-regulated in 'D0351', but was down-regulated in 'D9320'. CsDIR16 overexpression lowered PM residues, and these were more rapidly reduced in CsDIR16(+) transgenic 'D9320' plants than in wild-type 'D9320' and CsDIR16(-) transgenic plants.
Analyses of the CsDIR16-expression patterns in the cucumber cultivars with the highest and lowest levels of PM residue, and transgenic validation indicated that CsDIR16 plays a positive role in reducing PM residues. The findings of this study help understand the regulatory mechanisms occurring in response to PM stress in cucumbers and in establishing the genetic basis for developing low-pesticide residue cucumber cultivars.
黄瓜霜霉病是一种重要的病害，可严重影响黄瓜的生产。丙森锌，又名丙基-[3-（二甲基氨基）丙基]氨基甲酸酯（PM），是一种高效的氨基甲酸酯类杀菌剂，广泛应用于农业生产中，特别是防治黄瓜霜霉病。然而，在病害得到控制后，黄瓜中仍可能残留 PM。为了探究 PM 残留的分子机制，本研究选用 PM 残留量最高的黄瓜品种‘D9320’和最低的黄瓜品种‘D0351’进行研究。高通量标签测序（Tag-Seq）结果表明，CsDIR16 基因与 PM 残留有关，该结果通过转基因技术得到了验证。
我们研究了受 PM 处理诱导时，黄瓜中一个编码导向酶蛋白的基因 CsDIR16 的活性。PM 处理后，‘D0351’植株的果实、叶片和茎中的 CsDIR16 基因表达水平上调。然而，在品种‘D9320’中，PM 处理后叶片和茎中的 CsDIR16 水平下调，果实中无显著差异。茉莉酸、脱落酸、聚乙二醇 4000、NaCl 和柯赫氏尾孢（Cor）诱导均可使‘D0351’和‘D9320’中 CsDIR16 上调。水杨酸处理后，‘D0351’中 CsDIR16 的表达上调，而‘D9320’中则下调。CsDIR16 过表达降低了 PM 残留量，且在 CsDIR16(+)转基因‘D9320’植株中的 PM 残留量比野生型‘D9320’和 CsDIR16(-)转基因植株中下降得更快。
对 PM 残留量最高和最低的黄瓜品种的 CsDIR16 表达模式进行分析，并通过转基因进行验证，表明 CsDIR16 对降低 PM 残留量具有积极作用。本研究有助于了解黄瓜对 PM 胁迫的响应调控机制，并为培育低农药残留的黄瓜品种提供了遗传基础。
