基于转录组分析弱光胁迫对葡萄幼苗的影响

Transcriptional analysis of grape in response to weak light stress

摘要:

葡萄在生长过程中，常常暴露在光照不足的环境条件下，弱光严重影响葡萄的正常生长发育。为了探究弱光胁迫对葡萄生理生化的影响，本研究以‘鄞红’葡萄幼苗为试验对象，对其在不同弱光强度胁迫下（CK、T1、T2、T3和T4，胁迫强度逐渐增大）各种生理指标变化及部分处理组的转录组进行分析。结果表明，低强度弱光胁迫对葡萄光合作用以及生理生化的影响并不显著；随着胁迫强度的增大，葡萄叶片表皮层、栅栏组织、海绵组织变薄，海绵组织和栅栏组织细胞间隙变大，过氧化氢酶活性、过氧化物酶活性和超氧化物歧化酶活性逐渐下降，同时可溶性蛋白含量下降，游离脯氨酸含量上升。在遮光率为80%的胁迫下，葡萄光合作用以及其他生理生化各指标均发生显著变化。RNA-seq数据显示CK和T2、CK和T4、T2和T4的差异表达基因分别为13 913、13 293和14 943个，大部分差异代谢通路均与植物的抗逆响应密切相关；多个抗逆信号通路的基因表达发生变化，包括JA/MYC2途径、MAPK信号途径。此外多酚氧化酶、硫氧还蛋白等多个抗氧化相关基因以及光敏色素相关基因的表达也发生变化，以上结果表明，在弱光胁迫下，‘鄞红’葡萄可能通过调整活性氧清除剂的表达水平，以维持体内活性氧的平衡状态，同时通过调整光合色素和光反应结构蛋白的表达水平，以维持体内光合作用的平衡与正常运作。本研究将为葡萄耐弱光生理响应机制的探究、抗弱光葡萄品种的选育及设施栽培条件的优化提供理论与技术支持。

关键词:葡萄;弱光胁迫;转录组;MYC2

Abstract:

Grape (Vitis vinifera L.) in production is frequently exposed to inadequate light, which significantly affects its agronomic traits via inhibiting their physiological, metabolic and developmental processes. To explore the mechanism how the grape plants respond to the weak light stress, we used ‘Yinhong’ grape and examined their physiology-biochemistry characteristics and transcriptional profile under different levels of weak light stress. The results showed that grape seedlings upon low intensity shading treatments were not significantly affected. As the shading stress intensity was strengthened, the epidermis cells, palisade tissue, and spongy tissue in the leaves were thinner, the intercellular space between the palisade tissue and spongy tissue was larger compared with that of the control, and the activities of superoxide dismutase, catalase and peroxidase were decreased gradually. Additionally, the soluble protein content increased and the free proline content decreased gradually. Compared with the control, significant changes in plant photosynthetic characteristics and physiology-biochemistry characteristics were observed under high intensity of shading (80%). RNA-seq data showed that the differentially expressed genes between CK and T2, CK and T4, T2 and T4 were 13 913, 13 293 and 14 943, respectively. Most of the enrichment pathways were closely related with the plant's response to stress. Several signaling pathways in response to stress-resistance, e.g. JA/MYC2 pathway and MAPK signal pathway, were activated under weak light stress. The expression level of a variety of genes related to antioxidation (such as polyphenol oxidase and thioredoxin), photosynthesis (such as phytochrome) was altered under weak light stress, indicating that ‘Yinhong’ grape may activate the antioxidation related pathways to cope with reactive oxygen species (ROS). In addition, it may activate the expression of photosynthetic pigment and light reaction structural protein to maintain the photosynthesis activity. This research may help better understand the relevant physiological response mechanism and facilitate cultivation of grape seedlings under weak light.

Key words:grape;weak light stress;transcriptome;MYC2