FeSO_4引发提高秦艽种子萌发的生理机制

Physiological mechanism of FeSO_4 priming improvement of seed germination performances of Gentiana macrophylla

为探讨FeSO4引发提高秦艽种子萌发抗性的生理机制,同时设置水引发处理,以未作任何处理的种子为对照(CK),研究了0.6%FeSO4引发处理24 h对种子膜透性、储藏性物质、能量、激素及抗性相关酶等方面的影响。结果表明:FeSO4引发降低了种子膜透性,提高种子活力,在吸水12 h和24 h时,电导率分别较CK降低了6.61%和11.67%;调动了种子内部储藏物质的代谢,蔗糖含量减少9.57%,可溶性蛋白增加49.63%,饱和脂肪酸中的豆蔻酸和木焦油酸甲酯含量分别增加4.93%和9.03%,不饱和脂肪酸中的山嵛酸、油酸、亚油酸和亚麻酸分别减少6.73%、8.18%、8.40%和6.70%;改变了种子激素平衡,其中脱落酸的含量下降64.78%,赤霉素含量增加近22倍;加速了种子能量代谢, ATP含量增加2.16倍,细胞色素C氧化酶活性增加67.91%。此外,FeSO4引发使线粒体非酶促系统中谷胱甘肽含量和抗坏血酸的含量分别增加74.08%和10.89%,使细胞内酶促系统超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶活性分别增加285%、179%以及19.6%。因此,FeSO4引发对种子萌发是一个综合过程,一方面可促进种子物质代谢和提高能荷水平,一方面可改善种子内部生理状态和提高胁迫响应能力,从而提高种子活力,促进种子快速和整齐萌发。

Gentiana macrophylla is a widely used ingredient in traditional Chinese medicine for more than 2 000 years.Now,it is under third-class protection in China and on the list of National Key Protected Wild Herbs.G.macrophylla is a seed-propagated plant with extremely low germination rate.Short seed vigor,lower seed yield and after-ripening severely hinder its seedling establishment and significantly raise nursery cost.Various priming methods have shown that ferrous priming is better than other liquid priming,having higher germination performance under both optimal and adverse environments than non-primed seeds.The objectives of this study was to investigate the physiological mechanism of FeSO4 priming increasing seed germination performance of G.macrophylla to lay the theoretical basis for FeSO4 priming in abiotic stress response and application of FeSO4 priming technology in other plants seeds.Compare with non-priming of seeds,we investigated the effects of 0.6%FeSO4 priming on seed membrane permeability,stored material metabolism,energy metabolism,hormone homeostasis and enzyme activity.In this study,we noted that FeSO4 reduced seed membrane permeability and improved seed vigor by decreasing electrical conductivity by 6.61%at 12 h,11.67%at 24 h.The mobilization of stored materials such as sugars,proteins and fatty acids were activated,sucrose content decreased by 9.57%,and soluble protein content increased by 49.63%.With regard fatty acids,content of saturated fatty acids increased by 4.93%for myristic acid and 9.03%for methyl lignocerate.Then the content of unsaturated fatty acids decreased by 6.73%for behenic acid,8.18%for oleic acid,8.40%for linoleic acid and 6.70%for inolenic acid.In addition,FeSO4 priming altered hormone homeostasis of seeds between ABA and GA,of which ABA content decreased by 64.78%and GA content increased by nearly 22 times.In terms of energy metabolism,FeSO4 priming remarkably improved energy level,increased ATP content by 2.16 times and increased cytochrome C oxidase activity by 67.91%.Moreover,FeSO4 priming acted as an initial stress-exposure,both enzyme-catabolized and non-enzyme-catabolized systems response to environmental stress were activated.This was specifically so for the activities of SOD,CAT,APX of enzyme-catabolized elements,which increased by 2.85 times,1.79 times and 19.6%,respectively.The contents of non-enzyme-catabolized elements were increased by 74.08%for glutathione and 10.89%for ascorbic acid.In summary,our study indicated that regulation of FeSO4 priming was a complex process that promoted stored material mobilization,ATP biosynthesis,key enzyme activation,phytohormone homeostasis between ABA and GA;and simultaneously regulated both enzymatic-catabolized and non-enzymatic-catabolized effecters in biotic and an-biotic stress.On the one hand,priming induced more advanced development in seeds towards complete germination than unprimed ones.On the other hand,priming was considered as a pre-germination stress-exposure that left seeds with“stress-memory”and improved anti-adversity ability.These changes were not eliminated even when seeds dried to original moisture content.This was the main reason why priming enhanced seed vigor and rapid,uniform seed germination performance.