热激蛋白70（Heat shock protein 70,HSP70）是一类结构保守的分子伴侣类型应激蛋白,在调控动植物新陈代谢和信号传导方面发挥重要作用。本研究以谷子基因组数据库为基础,利用生物信息学方法鉴定了谷子HSP70基因家族成员,并对其序列的保守性、保守基序分布、内含子-外显子结构、在染色体上的分布以及系统发育关系进行了分析。结果表明,谷子HSP70家族是一个至少包含25个成员的多基因家族,基因编码区介于295~851个氨基酸之间;家族成员共有10类保守基序,长度分布于17~50个氨基酸之间;结构分析表明,各成员的内含子数目位于0~8之间,约一半的成员含有3’和5’非编码区;各成员不均匀地分布于第1,2,3,4,5,6,7和9号染色体上;系统发育关系揭示其成员之间具有较高的遗传多样性。该研究不仅有助于为了解该基因家族的进化起源提供参考,而且可为进一步分析该家族成员的功能奠定基础。
Polyamines play important roles in plant tolerance to environmental stress. With the aim of investigating the possible involvement of putrescine （Put） in salt-tolerance mechanisms in vegetable soybean roots, exogenous Put （10 mmol L＂） and its biosynthetic inhibitor D-arginine （D-Arg） （0.5 mmol L-1） were added to nutrient solution when vegetable soybean （Glycine max L. cv. Huning 95-1） seedlings were exposed to 100 mmol L^-11 sodium chloride （NaCl）. The results showed that Put ameliorated but D-Arg aggravated the detrimental effects of NaCl on plant growth and biomass production. Under NaCl stress, levels of free, soluble conjugated and insoluble bound types of Put in roots of vegetable soybean were reduced, whereas those of free, soluble conjugated, and insoluble bound types of spermidine （Spd） and spermine （Spm） were increased. Exogenous Put eliminated the decrease in Put but promoted the increase of Spd and Spm. However, these changes could be reversed by D-Arg. Under NaCl stress, activities of arginine decarboxylase （ADC）, S-adenosylmethionine decarboxylase （SAMDC）, diamine oxidase （DAO）, and polyamine oxidase （PAO） were induced, with exogenous Put promoting and D-Arg reversing these changes. Furthermore, NaCl stress decreased activities of antioxidant enzymes. Exogenous Put alleviated but D-Arg exaggerated these effects of NaCl stress, resulting in the same changes in membrane damage and reactive oxygen species （ROS） production. These results indicated that Put plays a positive role in vegetable soybean roots by activating antioxidant enzymes and thereby attenuating oxidative damage.
