冷激诱导高温胁迫下番茄幼苗矮化机理

Mechanism of dwarfing effect of tomato( Solanum lycopersicon) seedlings induced by coldshock treatment under high temperature stress

为了探明冷激诱导高温胁迫下番茄幼苗矮化的机理,育苗期间,每天8:00对幼苗分别进行5、10、15℃持续时间依次为10、20、30 min的冷激处理,测试了不同冷激强度下番茄幼苗乙烯释放速率,研究了冷激处理T10℃D10 min(10℃持续10 min)结合不同生长调节物质对番茄幼苗乙烯释放速率、赤霉素(GA3)含量和幼苗生长特性的影响.结果表明:冷激处理刺激了番茄幼苗乙烯的产生,随着冷激温度的降低和冷激时间的延长,冷激诱导乙烯释放的效应显著增强.5℃持续30 min的冷激处理番茄幼苗乙烯产生速率最大,达到60.3 n L·h-1·g-1,为对照的6.5倍;乙烯利(ETH)、硫代硫酸银(STS)、GA3和多效唑(PP333)均不能完全阻止冷激处理T10℃D10 min诱发的高乙烯产生率.冷激处理T10℃D10 min番茄幼苗茎叶GA3含量为80.8μg·g-1,与对照(130.6μg·g-1)相比降低了38.1%.喷施ETH、STS对冷激诱发的幼苗矮化效应无显著影响,而GA3显著减弱了冷激的矮化效应,PP333显著增强了冷激的矮化效应.以株高作为衡量指标,浓度为4.0 mg·L-1的PP333处理,相当于10℃冷激处理.冷激诱导的番茄幼苗矮化效应主要原因在于冷激降低了番茄幼苗茎叶GA3的含量.T10℃D10 min可以在降低幼苗株高的同时不降低幼苗干物质的积累.

To explore the dwarfing mechanism of tomato seedlings induced by cold-shock treatment followed by high temperature, tomato seedlings were subjected to cold-shock treatment once a day at 8：00 with temperature of 5, 10 and 15 ℃ for 10, 20 and 30 min, respectively, and ethylene pro- duction rate was measured. Plant height, ethylene production and gibberellin （ GA3 ） content of the seedlings treated with T10℃D10min（cold-shock with 10 ℃ for 10 min）, coupled with utilization of growth regulators, were also evaluated. The results showed that the release of ethylene was increased with the decrease of cold-shock temperature and extension of treatment time. The cold-shock treat- ment of 5 ℃ and 30 min had the highest ethylene production rate of 60.3 nL · h-1 · g-1, which was 6.5 times of the control. None of ethephon （ETH）, silver thiosulphate （STS）, GA3 or pa- clobutrazol （PP333） could completely block high ethylene production induced by cold-shock treat- ment. Tomato seedlings with cold-shock treatment （T10 ℃ Dao min ） resulted in reduction in GA3 con- tent by 38.1% compared with the value of control （130.6 μg ·g-l）. Neither ethephon nor STS had significant effect on the dwarfing induced by cold-shock. However, GA3 weakened the dwarfing effect induced by cold-shock treatment （T10℃ D10 min ） , while PP333 greatly enhanced it. The dwar- fing effect by cold-shock treatment of T10 ℃ D10min was equivalent to that of application of 4.0 mg · L-1 PP333 based on the seedling height as an evaluation indicator. It was concluded that cold- shock treatment stimulated shoot ethylene production and blocked GA3 synthesis. GA3 played a vital role in dwarfing effect on tomato seedling induced bv cold-shock treatment. Cold-shock with 10 ℃and duration of 10 min could promote the growth of tomato seedlings with shorter stem and higher dry mass accumulation.