低温胁迫下番茄幼苗根穗互作对其抗坏血酸—谷胱甘肽循环的影响

为探讨番茄根系与接穗及其互作效应影响嫁接苗耐冷性的效应大小与生理机制,以耐冷性强的番茄‘060112’(R)和冷敏感番茄‘060911’(S)为试材,采用靠接法进行嫁接,组成双根双穗嫁接苗RS/RS,待嫁接苗成活后通过断根或断穗,形成R/R、R/RS、R/S、S/R、S/RS和S/S共6个根/穗组合处理,置于光强22 klx、光周期12 h/12 h光照培养箱,测定昼夜温度10℃/3℃低温胁迫9 d及25℃/15℃常温恢复3 d时嫁接苗叶片和根系中活性氧水平及As A-GSH循环中关键酶和抗氧化物质的变化。结果表明,低温胁迫显著提高了番茄嫁接苗叶片和根系中H_2O_2含量及超氧阴离子产生速率,但耐冷性强的R根系嫁接苗活性氧水平显著低于冷敏感的S根系嫁接苗,虽然R接穗嫁接苗活性氧水平亦显著低于S接穗嫁接苗,但降幅不及根系嫁接苗的大,表明根系在增强嫁接苗耐冷性中的作用大于接穗。低温胁迫下,各处理嫁接苗叶片和根系As A-GSH循环中关键酶(APX、MDHAR、DHAR、GR)活性和抗氧化物质(As A、DHA、GSH、GSSG)的含量均显著增加,且除DHA和GSSG外,均以R根系或R接穗嫁接苗较高,S根系或S接穗嫁接苗较低,RS根系或RS接穗嫁接苗居中,表明低温胁迫下耐冷性强的R根系或接穗嫁接苗的抗氧化能力显著高于S根系或接穗嫁接苗。具RS双接穗的嫁接苗中又以RS-R叶片的抗氧化能力显著高于RS-S叶片,且互作效应的P值小于0.01(或0.05),表明根、穗对嫁接苗耐冷性存在显著的互作效应。

Effects of Rootstock and Scion Interactions on Ascorbate-Glutathione Cycle in Tomato Seedlings Under Low Temperature Stress

In order to investigate the effect of tomato rootstock，scion and their potential interaction on chilling tolerance，the approach grafting between chilling-sensitive tomato cultivar‘060911’（S）and chilling-resistant tomato cultivar‘060112’（R）was proceeded to generate grafted seedlings RS/RS with double rootstocks and scions. By selectively detaching one rootstock or scion from RS/RS，newly formed seedlings of six combinations with different rootstock and scion，i.e.，R/R，R/RS，R/S，S/R，S/RS，S/S were raised in the growth chamber with light intensity of 22 klx and photoperiod of 12 h/12 h. Seedlings were treated with low temperature at 10 ℃ in the day and 3 ℃ at night for 9 days and recovered at 25 ℃ in the day and 15 ℃ at night for 3 days. The level of reactive oxygen species（ROS），and the key enzymes and antioxidants in AsA-GSH cycle in leaves and roots of grafted seedlings were measured after the chilling treatment and recovery. The content of hydrogen peroxide and production rate of superoxide anion in leaves and roots of grafted tomato seedlings were significantly increased under low temperature stress. The ROS level in grafted seedlings with R rootstock or R scion was significantly lower than that with S rootstock or S scion，respectively. The decrease of ROS level between R and S rootstock was more significant than that between R and S scion，indicating that rootstock conferred more chilling resistance than scion. Low temperature stress increased the accumulation of AsA，DHA，GSH and GSSG，and enhanced the activities of APX，MDHAR，DHAR and GR. Moreover，enzyme activities and the content of antioxidants except for DHA and GSSG were highest in grafted seedlings with R rootstock or R scion，lowest in those with S rootstock or scion，and intermediate in those with RS rootstock or scion，indicating that the ability of anti-oxidation in grafted seedlings with R rootstock or R scion under cold stress was significantly higher than that in grafted seedlings with S rootstock or S scion. In addition，the ability of anti-oxidation in leaves of RS-R grafted seedling was significantly higher than that in RS-S grafted seedlings. Statistical analysis showed that probability（P）values of interaction between rootstock and scion were less than 0.01（or 0.05），indicating that rootstock and scion posses significant interaction effects on the chilling tolerance of grafted tomato seedlings.