塔里木盆地特有植物硬枝碱蓬耐盐机制及相关基因挖掘

Soil salinity is one of the most significant limiting factors in agriculture. There is about 1,300 million hectares affected by salt stress in Xinjiang Autonomous Region, the largest province in China. Halophytes are plant groups that survive after long-term natural selection to reproduce in salinity environments where the salt concentration is around 200 mM NaCl or more. Halophytes are a valuable natural salt tolerant gene pool. Suaeda rigida H. W. Kung et G. L. Chu is an endemic plant which is an euhalophyte with important economic and ecological value in Tarim Basin, Xinjiang. In this project, samples inculding S. rigida plants and seeds as well as the soil were collected from different saline environments of Tarim Basin. The optimal salt concentrations for S. rigida growth were determined. The morphological and anotomical features of S. rigida were investigated by microscopy. The physiological and biochemical characteristics associated with salt tolerance in S. rigida were investigated under different saline environments. To explore the expression of salt tolerance genes and regulatory networks of S. rigida in response to salt stress and screen ESTs related to salt stress, we will carry out the high-throughput RNA sequence (RNA-seq) and subtractive suppression hybridization (SSH) library of S. rigida under salt stress to generate diffential gene expression data sets, which should help understand the mechanisms of salt tolerance in S. rigida and isolate related genes. This project will provide valuable information about the salt tolerance species endemic to Tarim Basin at individual, cellular and molecular levels.

盐渍土壤是制约农业生产的重要因素之一，新疆有盐渍土0.13亿hm2，是我国盐渍土分布最广、面积最大的省区。盐生植物是在盐渍环境中经过长期自然选择生存下来的植物类群，是宝贵的天然耐盐基因资源，具有特殊价值的盐生植物更具开发意义，硬枝碱蓬是塔里木盆地的特有植物，是具有重要的经济价值和生态价值真盐生植物。本项目以采自塔里木盆地不同生境的硬枝碱蓬植株、种子及土壤为材料，通过理化分析确定适宜硬枝碱蓬生长的盐分含量；通过显微观察明确硬枝碱蓬在不同盐分下形态的差异；通过生化分析明确硬枝碱蓬在不同盐分下主要生理生化特性的变化；通过转录组测序 (RNA-seq)和抑制性消减杂交（SSH）技术，筛选盐胁迫下的差异表达基因，并进行功能验证，了解耐盐基因调控网络。从个体、细胞和分子水平多个层次研究硬枝碱蓬对盐胁迫的响应规律，以全面解析硬枝碱蓬耐盐机制，并挖掘相关基因，为开发塔里木盆地本土耐盐植物资源提供科学支撑。

硬枝碱蓬是塔里木盆地的特有植物，是具有重要的经济价值和生态价值真盐生植物。本项目利用HPLC指纹图谱法对不同采集地硬枝碱蓬进行分析，明确采集地点对样品的影响；对硬枝碱蓬种子基本形态进行解剖观察，分析其休眠原因为种皮机械障碍和种子内有抑制物；明确了打破其种子休眠的方法为150目砂纸打磨1.5 min + 900～1500 mg/L的GA3溶液浸泡24 h；进一步明确了其种子萌发的最适条件为(30℃、12 h黑暗)/(35℃、12 h光照)或(25℃、12 h黑暗)/ (30℃、12 h光照)；在此条件下，进行NaCl和NaHCO3胁迫实验，并与其他藜科植物的抗盐性进行比较，结果表明，硬枝碱蓬种子萌发期的耐NaCl的阈值和极限值分别为394.30 mmol/L和894.30 mmol/L，其耐NaCl能力，在塔里木盆地10种藜科植物中排名第2，仅次于盐穗木；硬枝碱蓬种子萌发期的耐NaHCO3的阈值和极限值分别为237 mmol/L和540 mmol/L，其耐NaHCO3能力，在塔里木盆地10种藜科植物中排名第4，排在盐节木、白茎盐生草、盐穗木之后，表现出较强的抗盐性；对硬枝碱蓬幼苗进行NaCl处理的结果表明，与对照（0）相比，在NaCl为100～500 mmol/L范围内，随着NaCl浓度升高，硬枝碱蓬幼苗的相对电导率和丙二醛（MDA）含量无显著变化，脯氨酸含量、可溶性糖含量、可溶性蛋白含量、过氧化氢酶（CAT）活性、过氧化物酶（POD）活性呈增加的趋势，硬枝碱蓬幼苗表现出较好的抗盐性；在不同时间点采集盐处理的硬枝碱蓬根、叶、茎，进行RNA-seq测序，挖掘耐盐基因，为开发塔里木盆地本土耐盐植物资源提供科学支撑。