关键词: 24- 表油菜素内酯, 亚低温, 番茄, 钾, 钾吸收转运相关基因

Abstract: Taking 2 tomato varieties‘Dongnong 708’（‘DN 708’） sensitive to low temperature and
‘Dongnong 722’（‘DN 722’）tolerant to low temperature as test materials，this paper studied the effects
of 24-epibrassinolide（EBR）on tomato growth and potassium accumulation under sub-low temperature
condition．The results showed that comparing with the suitable temperature，low temperature stress could
inhibit the seedling growth of these 2 tomato varieties，and remarkably reduce the maximum photochemical
efficiency of PSII （F_v/F_m），and K⁺ concentrations in stems and leaves，and significantly increase the
malondialdehyde（MDA）content and electrolyte permeability．Moreover，the effects of sub-low temperature
stress on‘DN 708’was greater than that on‘DN 722’．While，exogenous EBR effectively alleviated
the inhibition of sub-low temperature stress on tomato seedling growth，significantly improved F_v/F_m，K⁺
concentrations in roots，stems and leaves of these 2 tomato varieties，and increased relative expression levels of
LKT1，SIHAK5 and SIHAK9 genes in roots and leaves，and significantly reduced MDA content and electrolyte
permeability in seedlings of these 2 tomato varieties．And the variation range in‘DN 708’was greater
than that in‘DN 722’．To sum up，exogenous EBR may increase the K⁺ concentration in various organs of
tomato seedlings by promoting the expression of transport related genes and K+ absorption，reduce the degree
of cell membrane peroxidation，and enhance the adaptability of tomato seedlings to sub-low temperatures
condition．Thus，exogenous EBR has a greater mitigation effect on low temperature sensitive tomato variety‘ DN
708’ under sub-low temperature stress than low temperature tolerant tomato variety‘ DN 722’．

Key words: 24-epibrassinolide, sub-low temperature, tomato, potassium, K⁺ absorption and transport related gene