盐胁迫对线辣椒根系生长及基因表达的影响

Effects of Salt Stress on Root Growth and Gene Expression of Capsicum annuum L.

为研究线辣椒耐盐机理,以线辣椒耐盐品种‘强丰7301’和盐敏感品种‘GX7’为材料,用50、100、150、200、250mmol·L-1的NaCl溶液对其幼苗进行胁迫处理,研究盐胁迫对线辣椒幼苗根系形态、根系生长参数的影响,用250mmol·L-1的NaCl溶液对其幼苗进行胁迫处理研究对根系基因表达的影响。结果表明,随着盐浓度的升高,根系的颜色从乳白色逐步变为褐色;低浓度盐胁迫(50和100 mmol·L-1的NaCl溶液)可以促进‘强丰7301’幼苗根系的生长,150mmol·L-1及其以上的高浓度盐胁迫则对‘强丰7301’幼苗根系的生长具有抑制作用;而5个浓度的盐胁迫处理对‘GX7’幼苗根系的生长均具有明显的抑制作用。在盐胁迫3 h、6 h和12 h后2个品种都有大量的基因差异表达,‘GX7’和‘强丰7301’在盐胁迫后差异表达基因的数量随时间的延长而增加,在12 h达到最大,上调基因和下调基因几乎各占一半。通过GO注释分析,‘强丰7301’与根系耐盐有关的差异表达基因在细胞成分、分子功能和生物学过程3个GO分支中均有分布,涉及到根形态发生、渗透胁迫反应、细胞生长、细胞内膜结合细胞器及谷胱甘肽转移酶活性等过程,说明这些基因的差异表达与其耐盐性有关;将‘强丰7301’在3个时间点筛选出的与根系生长发育有关的基因注释到KEGG数据库,有11个基因在所有时间点均发生了差异表达,且集中在胞吞作用、谷胱甘肽代谢、真核生物中的核糖体生物合成、吞噬体、苯丙氨酸代谢、苯丙素生物合成和植物激素信号转导等方面,说明‘强丰7301’的耐盐与上述代谢过程有关。

In order to provide reference for the research of salt tolerance mechanism of Xianlajiao chili pepper( Capsicum annuum L.),the cultivar ‘Qiangfeng 7301’ and ‘GX7’ were used as materials. NaCl solutions of 50,100,150,200 and 250 mmol·L ^-1 were used to treat the seedlings under stress. The effects of salt stress on root morphology and root growth parameters of Xianlajiao chili pepper seedlings were studied.NaCl solution of 250 mmol·L^-1 was used to treat the seedlings under stress. The effects of salt stress on root gene expression were studied. The results showed that the root color changed from milky white to brown with the increase of salt concentration.Low concentration salt stress(NaCl solution of 50 and 100 mmol·L ^-1 ) could promote root growth of ‘Qiangfeng 7301’ seedlings. High concentration salt stress of 150 mmol·L ^-1 and above inhibited root growth of ‘Qiangfeng 7301’ seedlings. Salt stress treatment of 5 concentrations significantly inhibited root growth of ‘GX7’ seedlings. After salt stress for 3 h,6 h and 12 h,there was a large amount of gene differential expression in both varieties.The number of differentially expressed genes of ‘GX7’ and ‘Qiangfeng 7301’ increased with the extension of time after salt stress,it reached the maximum at 12 h ,with up-regulated genes and down-regulated genes accounting for almost half.Through GO annotation analysis,differentially expressed genes related to root salt tolerance of ‘Qiangfeng 7301’ were distributed in three GO branches,namely,cell components,molecular functions and biological processes,itinvolved root morphogenesis,osmotic stress response,cell growth,endometrium-binding organelles and glutathione transferase activity. The results indicated that the differential expression of these genes was related to salt tolerance.Genes of ‘Qiangfeng 7301’ related to root growth and development were selected at 3 time points and annotated into the KEGG database.The 11 genes were differentially expressed at all time points,and they were mainly involved in endocytosis,glutathione metabolism,ribosome biosynthesis in eukaryotes,phagosome,phenylalanine metabolism,phenylpropanoids biosynthesis and plant hormone signal transduction.The salt tolerance of ‘Qiangfeng 7301’ was related to the above metabolic process.