Effects of water stress and NaCl stress on different life cycle stages of the cold desert annual Lachnoloma lehmannii in China

For a plant species to complete its life cycle in arid and saline environments,each stage of the life cycle must be tolerant to the harsh environmental conditions.The aim of the study was to determine the effects of water stress(water potentials of–0.05,–0.16,–0.33,–0.56,–0.85 and–1.21 MPa)and NaCl stress(50,100,200,300,400,500 and 600 mmol/L NaCl)on seed germination percentage,seedling survival and growth,juvenile growth and plant reproduction of Lachnoloma lehmannii Bunge(Brassicaceae),an cold desert annual that grows in the Junggar Basin of Xinjiang,China in 2010.Results indicated that low water stress(–0.05 and–0.16 MPa)had no significant effect on seed germination percentage.With a decrease in water potential,germination percentage decreased,and no seeds germinated at–0.85 and–1.21 MPa water stresses.Germination percentage of seeds was significantly affected by NaCl stress,and higher germination percentages were observed under non-saline than saline conditions.An increase in NaCl concentrations progressively inhibited seed germination percentage,and no seeds germinated at ≥400 mmol/L NaCl concentration.Non-germinated seeds were transferred from both PEG(polyethylene glycol-6000)and NaCl solutions to distilled water for seed germination recovery.The number of surviving seedlings and their heights and root lengths significantly decreased as NaCl stress increased.About 30% of the plants survived and produced fruits/seeds at 200 mmol/L NaCl concentration.Thus,seed germination,seedling establishment and reproductive stage in the life cycle of L.lehmannii are water-and salt-tolerant,with seedlings being the least tolerant.These tolerances help explain why this species can survive and produce seeds in arid and saline habitats.

两种早春短命植物CBF基因的原核表达分析

【目的】在原核表达系统中高效表达真核生物中与抗寒相关的转录因子CBF基因,验证序列的正确性,摸索高效表达的条件,为后续转录因子的功能验证奠定基础。【方法】以具有耐低温胁迫的两种早春短命植物绵果荠和卷果涩荠为材料,扩增两端有NcoⅠ和Hind III酶切位点的Ll CBF和Ms CBF基因的CDS全长,构建原核表达载体p ET32a-Ll CBF和p ET32a-Ms CBF,并将其转入Rosetta(DE3)菌株,进行了15、25、30和37℃下不同IPTG浓度的诱导表达;选择表达量最大时的温度及IPTG浓度进行不同时间的诱导表达;对高效表达条件下收集的菌体沉淀超声破碎,离心后同时收集上清和沉淀并进行煮沸处理,SDS-PAGE电泳检测融合蛋白可溶性。【结果】Ll CBF蛋白在30℃、IPTG浓度1 mmol/L、20 h表达量达到最大,Ms CBF蛋白在30℃、IPTG浓度2 mmol/L、20 h达到最大表达量。【结论】探索出了在原核表达系统中高效表达目的蛋白的最适条件,Ll CBF蛋白和Ms CBF蛋白表达形式均为包涵体。

早春短命植物绵果荠愈伤组织诱导相关因素研究

绵果荠是分布在新疆北部准噶尔荒漠中的十字花科一年生早春短命植物。本研究为探讨绵果荠愈伤组织诱导条件,以无菌苗子叶为外植体,研究了不同苗龄、培养基种类、蔗糖浓度和培养条件对愈伤组织的诱导及其生长的影响。结果表明,1)愈伤组织诱导的最佳条件为:苗龄14d、培养基为MS+1.0mg/L IBA+0.1mg/L BAP、含糖量3%、温度25℃和光照为黑暗。2)愈伤组织生长的适宜条件是光照16h/d和温度25℃。

早春短命植物绵果荠无菌苗组织培养相关因素研究

为建立绵果荠(Lachnoloma lehmannii)无菌苗培养体系,以种子作为试验材料,对不同消毒方法的效果进行了比较,并对影响种子萌发、幼苗生长相关因素进行了探讨。结果表明,1)种子消毒适宜方法为种子流水冲洗1～2min,70%酒精浸泡1min,0.1%HgCl2消毒1.5min;2)光照对种子萌发有促进作用,而幼苗的不同部位对光照有不同响应;3)种子萌发对低温有依赖性,而幼苗生长需要一定的高温;4)适宜激素对种子萌发有促进作用,而幼苗的不同部位对激素有不同反应。因此,绵果荠种子萌发和幼苗生长适合培养体系为把种子消毒后接种无激素的MS,放在变温为15℃/5℃的光照条件下培养4～5d,萌发后转至温度为(25±1)℃的光照条件下培养,发芽率达到90%,比对照高16%,且幼苗长势良好。

绵果荠CBF基因启动子克隆及诱导特性分析

CBF基因不仅是植物CBF抗冷途径的枢纽,而且可以提高植物的抗冷能力。而植物的抗冷能力的提高是由于CBF基因调控下游抗冷基因的表达来实现的。本研究根据前期已克隆得到的绵果荠Ll CBF基因(JQ687132)序列,利用TAIL-PCR方法从新疆早春短命植物绵果荠基因组DNA中分离得到Ll CBF基因编码区上游1 172 bp启动子序列;将该序列连入克隆载体并测序,通过生物信息学分析表明,该序列含TATAbox、CAAT-box等典型的真核生物核心启动子元件,同时具有等逆境响应相关元件。在烟草叶片中的瞬时表达分析,进一步表明,在低温、干旱及盐胁迫诱导下该启动子序列具有驱动GUS报告基因表达的特性。本研究对新疆早春短命植物种质资源的开发利用及丰富作物逆境基因工程诱导启动子资源具有重要的实践意义。