NaCl胁迫对甜瓜生理指标及相关基因表达的影响

以薄皮甜瓜(IVF05、IVF89)和厚皮甜瓜(IVF117、IVF303)为试材,研究Na Cl(150 mmol·L~(-1))处理对4个甜瓜品种发芽、幼苗生长及相关基因表达的影响。结果表明,在Na Cl胁迫下,薄皮甜瓜IVF89的生长指标受到的抑制作用最大,其发芽率、发芽指数、胚根长度和胚轴长度分别下降23百分点、76.24%、46.71%和39.27%;厚皮甜瓜IVF303的生长指标受到的抑制作用最小,其发芽率下降不明显,发芽指数、胚根长度和胚轴长度分别下降46.52%、34.86%和23.08%;Na Cl胁迫提高了甜瓜幼苗叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性,增加了游离脯氨酸(Pro)、丙二醛(MDA)、可溶性蛋白的含量;4个甜瓜品种幼苗的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和SPAD值均显著降低,IVF05、IVF89、IVF117和IVF303的Pn分别下降了64.44%、69.62%、61.23%、60.00%;4个甜瓜品种的卡尔文循环(Calvin)关键酶基因1,5-二磷酸核酮糖羧化酶/加氧酶基因(CmRubisco)、3-磷酸甘油酸激酶基因(CmPGK)和叶绿体型果糖-1,6-二磷酸酶基因(Cm FBPase)表达均显著下调,核酮糖-5-磷酸激酶基因(Cm PRK)表达大多上调;甜瓜耐盐相关基因质膜Na~+/H~+逆向转运蛋白基因(Cm SOS1)、液泡膜Na~+/H~+逆向转运蛋白基因(CmNHX1)、高亲和力K~+转运体基因(CmHKT1)和N-乙酰氨基葡萄糖基转移酶基因(CmGnT)的表达均上调,其中IVF303的基因表达上调幅度最大。通过主成分分析、相关分析和聚类分析等综合分析方法,将4个甜瓜品种分为3类,IVF05和IVF89为盐敏感类型,IVF117为中耐盐类型,IVF303为强耐盐类型。

Effects of NaCl Stress on Physiology Index and Related Gene Expression in Melon

This paper studied the effects of NaCl（150 mmol · L-1）treatment on germination，seedling growth and related gene expression of 4 melon cultivars（thin-skinned melon IVF05，IVF89 and thick-skinned melon IVF117，IVF303）．The results showed that under NaCl stress，the growth indexes of thin-skinned melon IVF89 were severly inhibited. Its germination rate，germination index，radicle length and hypocotyl length were decreased by 35.00%，76.24%，46.71% and 39.27%，respectively. While，the growth indexes of thick-skinned melon IVF303 were least inhibited. Its germination rate did not decrease obviously，germination index，radicle length and hypocotyl length were decreased by 46.52%，34.86% and 23.08%，respectively. NaCl stress could increase the activities of antioxidant enzymes superoxide dismutase（SOD），peroxidase （POD）and catalase（CAT）in the leaves of melon seedlings，and increased the contents of free proline（Pro）， malondialdehyde（MDA）and soluble protein. The net photosynthetic rate（Pn），transpiration rate（Tr）， stomatal conductance（Gs）and SPAD values of these 4 melon cultivar seedlings were significantly decreased． The Pn of IVF05，IVF89，IVF117 and IVF303 were decreased by 64.44%，69.62%，61.23% and 60.00%， respectively. And the expression of key enzyme genes in Calvin cycle（CmRubisco，CmPGK and CmFBPase） of the 4 cultivars was significantly down-regulated，while the expression of CmPRK was up-regulated. The expression of salt-tolerant genes（CmSOS1，CmNHX1，CmHKT1 and CmGnT）was up-regulated. Among them，the gene expression of cultivar IVF303 had the largest range of up-regulation. These 4 melon cultivars were divided into 3 categories by principal component analysis，correlation analysis and cluster analysis. IVF05 and IVF89 were of salt-sensitive type，IVF117 was of moderate salt-tolerant type，and IVF303 was of strong salt-tolerant type．