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以2个反义转酮醇酶基因(CsTK)黄瓜株系T2′-2和T2′-4以及野生型黄瓜‘08-1’为试材,研究CsTK沉默对高温(40℃)下黄瓜幼苗净光合速率(P_n)、核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)活性及其mRNA表达量和叶绿素荧光参数的影响。结果表明,与野生型相比,2个反义株系的转酮醇酶(TK)活性和CsTK mRNA的表达量显著降低。高温胁迫2h后,黄瓜幼苗叶片的P_n、气孔导度(G_s)以及以吸收光能为基础的光化学性能指数(PI_(ABS))、Rubisco活性及其mRNA表达量和光系统(PSⅡ)活性均显著降低,而CsTK的mRNA表达量和TK活性及胞间CO_2(C_i)浓度明显升高,但2个反义株系各指标始终低于野生型植株,尤其‘T2′-4’最低。CsTK沉默加剧了高温条件下黄瓜幼苗Rubisco和PSⅡ活性的降低,从而导致转反义CsTK黄瓜幼苗的光合作用降低幅度较大,对高温耐性下降。
Two antisense transketolase genes (CsTK) cucumber lines T2’-2 and T2’-4 and wild-type cucumber ’08 -1 ’were used as materials to study the effect of CsTK silencing on the growth of cucumber seedlings under high temperature (40 ℃) Net photosynthetic rate (P_n), Rubisco activity, mRNA expression level and chlorophyll fluorescence parameters. The results showed that the transketolase (TK) activity and the expression of CsTK mRNA in two antisense plants were significantly decreased compared with the wild type. P_n, stomatal conductance (G_s), and photochemical index (PI_ (ABS)), Rubisco activity, mRNA expression level and PSⅡ activity of cucumber seedling leaves were significantly higher after 2h of high temperature stress While the CsTK mRNA expression, TK activity and intercellular CO 2 (C_i) concentration were significantly increased. However, the indexes of the two antisense plants were always lower than those of wild type plants, especially the lowest of ’T2’-4’. CsTK silencing exacerbated the decrease of Rubisco and PSⅡ activity in cucumber seedlings under high temperature conditions, which led to the decrease of photosynthesis and the decrease of high temperature tolerance of antisense CsTK seedlings.