不同去果面蜡粉能力砧木影响嫁接黄瓜抗冷性机制

Grafting is an important agronomic technique to improve tolerance of cucumber to biological and abiotic stress, promote growth and increase yield, especially for protected cultivation in north China in winter with low temperature and weak light. In order to improve the commercial and nutritional quality of grafted cucumber fruit, bloom-removing white (yellow) seed pumpkin instead of Yunnan Figleaf Gourd was used as cucumber rootstock in the production in recent years, but at the same time, the tolerance to low temperature and weak light and the growth were weakened , and yield was reduced. In order to explore the mechanism of cold-tolerant difference in grafted cucumber by rootstocks with different bloom-removing ability, different rootstocks was used to graft cucumber, and self-rooted cucumber was as control, by setting low temperature stress and silicon treatment, the epidermis structure and silicon distribution were observed by electron microscopy and in situ X-ray technique, the cold-induced metabolism and signal transduction pathway (including miRNA) were studied by high performance liquid chromatography and high throughput sequencing, the qRT-PCR was used to detect the expression of silicon metabolism related and cold tolerance related genes, the specific protein expression was analyzed by iTRAQ quantitative proteimic analysis; in order to reveal the mechanism of different types of rootstocks affecting cold tolerance of grafted cucumber by the way of signal transduction and silicon metabolism.

嫁接是增强黄瓜对生物和非生物胁迫抗性，促进生长，提高产量的重要农艺技术，尤其对我国北方地区冬季低温弱光下设施生产具有重要意义。为提高嫁接黄瓜果实商品性和营养品质，近年来生产中逐渐用去蜡粉能力强的白（黄）籽南瓜替代黑籽南瓜作为砧木，但同时带来耐低温弱光能力下降，生长势减弱，产量降低等问题。为探明不同去蜡粉能力砧木影响嫁接黄瓜抗冷性的机制，本项目选用去蜡粉能力不同的砧木南瓜嫁接黄瓜，以自嫁接黄瓜为对照，通过低温胁迫和加硅处理，借助电镜和原位X射线技术观测嫁接黄瓜叶片表皮细胞结构及硅沉积分布特征，通过高效液相色谱分析和高通量测序技术研究嫁接黄瓜抗冷相关代谢过程和砧-穗信号(miRNA等)传导途径，利用qRT-PCR技术检测嫁接黄瓜硅代谢相关基因及抗冷相关基因转录因子表达特性，利用iTRAQ定量蛋白组分析技术研究特异蛋白表达特性，以期从信号传导和硅代谢角度揭示不同类型砧木嫁接黄瓜抗冷性差异机制。

果面蜡粉是黄瓜重要的商品品质性状。嫁接是促进黄瓜生长，提高抗性和产量的重要农艺技术，但不同去果面蜡粉能力砧木对嫁接黄瓜抗冷性影响不同。本项目选用去蜡粉强的砧木‘黄诚根2号’和弱的砧木‘云南黑籽南瓜’嫁接‘新泰密刺’黄瓜，以自根黄瓜为对照，通过水培加硅和低温处理，观测细胞结构、生理生化和分子生物学变化，从硅代谢和信号传导角度揭示砧木影响嫁接黄瓜抗冷性机制。结果表明：幼苗生长、叶片厚度、栅栏组织和海绵组织厚度，嫁接黄瓜大于自根黄瓜，加硅处理大于不加硅处理，砧木影响大于硅营养。不同器官中硅含量高低为叶片＞根系＞茎；低温胁迫下，器官硅含量和硅转运蛋白基因表达量均呈先升高后降低趋势；与自根黄瓜相比，‘云南黑籽南瓜’促进嫁接黄瓜硅吸收和硅转运蛋白基因表达，‘黄诚根2号’则起抑制作用；加硅显著增加自根和嫁接黄瓜各器官硅含量，但抑制硅转运蛋白基因表达。砧木和硅营养均能提高黄瓜幼苗抗冷性，以砧木作用更明显，‘云南黑籽南瓜’作用大于‘黄诚根2号’。生理测定、miRNA测序、转录组和蛋白组关联分析表明，砧木通过提高离子转运、促进丙酮酸和苯丙烷生物合成以及调节谷胱甘肽、α-亚麻酸和亚油酸代谢增强黄瓜幼苗抗冷性，硅通过促进苯丙烷生物合成、调节磷脂酰肌醇信号系统以及促进糖代谢和次生代谢增强黄瓜幼苗抗冷性；‘云南黑籽南瓜’比‘黄诚根2号’嫁接黄瓜具有更强的激素合成、α-亚麻酸、亚油酸和谷胱甘肽代谢能力。本研究结果阐明了砧木和硅对黄瓜抗冷性的影响差异，为深入研究不同类型砧木嫁接黄瓜冷胁迫响应机制奠定了基础。