黄瓜的冷害及耐冷性

A Review on Chilling Injury and Cold Tolerance in Cucumis sativus

随着蔬菜反季节栽培面积的不断扩大,如何提高黄瓜(Cucumis sativus L.)耐冷性已成为选育新品种的研究重点。系统地综述近几年黄瓜耐冷性的鉴定、获得途径、冷害机理以及遗传和分子遗传学等方面的研究,以促进对黄瓜冷害机制的研究, 加速耐冷品种的培育。耐冷性鉴定时要从耐冷指数、低温发芽能力、MDA (丙二醛)含量和电解质渗漏率等几个方面综合鉴定。耐冷性的获得途径主要有冷驯化、激素处理、热激处理和培育耐低温品种,最重要的途径是耐冷品种选育。黄瓜冷害机理包括细胞膜的流动性降低及透性增加,光合作用被抑制,根系吸收减弱,可溶性糖含量减少,淀粉粒积累增加,微管的稳定性受到破坏等。黄瓜低温发芽能力由非加性基因决定,而幼苗时期主要由加性基因控制。黄瓜耐冷的分子遗传学研究进展缓慢,目前已克隆出在低温锻炼中特异表达的功能未知的基因CCR18。今后还应研究黄瓜低温胁迫时的信号转导系统,以进一步揭示黄瓜的冷害机理;利用野生资源的抗逆性状,拓宽栽培黄瓜的遗传基础,选育适于保护地栽培的耐低温品种。

With continuous expansion of the area for protected cultivation,how to improve chillingtolerance in cucumber has become one of the major objectives in current cucumber breeding program.In present paper,the advances on the estimation of chilling tolerance,the approaches to improvechilling tolerance in cucumber and the mechanisms of chilling injury,heredity and molecular genet-ics of chilling tolerance were systemically reviewed. It was necessary to estimate the chilling toler-ance in cucumber according to the integration of indexes,such as, the germinating ability under lowtemperature,the content of MDA and the leakage rate of electrolyte. Cold acclimation,treatingwith hormones,heating shock and breeding new varieties with chilling tolerance were used toimprove chilling tolerance in cucumber,in which the last one was thought to be the most importantone. The decrease of fluidity and increase of permeability of cytomembrane,the repression ofphotosynthesis,the weakening of absorbance in cucumber root,the reduce of soluble sugarcontent, the accumulation of starch grains and the destroy of stability of microtubules were involvedin the mechanisms of chilling injury in cucumber. The germinating ability at low temperature wasdetermined by non-additive genes,while the chilling tolerance was controled in young plants byadditive genes. The molecular genetics of chilling tolerance in cucumber was rarely reported,exceptfor an unknown function gene CCR18 which expressed specifically during low temperature acclima-tion was cloned. The signal transduction system should also been studied in order to further discoverthe mechanisms of chilling injury,and the trait of stress-tolerance in wild cucumber species shouldbeen explored to widen the genetic basis and breed the new varieties with cold tolerance adaptable toprotected culture.