壳聚糖引发对盐胁迫下水稻种子萌发及幼苗生长的影响

Effects of Chitosan Priming on Seed Germination and Seedling Growth of Rice Under Salt Stress

【目的】盐胁迫是影响作物生长及产量的重要胁迫,探究壳聚糖(chitosan,CTS)引发对盐胁迫下水稻种子萌发及幼苗生长的影响,并筛选出缓解胁迫的最优质量浓度,对于保障粮食安全意义重大。【方法】以皖稻16为材料,采用100 mmol/L NaCl溶液模拟盐胁迫,设置0,50,100,150,200,250 mg/L的CTS溶液引发水稻种子,以未引发无盐胁迫处理作为对照1(CK),未引发有盐胁迫处理作为对照2(S-CK)。测量水稻种子发芽指标以及根苗生长状况,并监测水稻幼苗抗氧化酶活性和糖代谢指标。【结果】与CK相比,盐胁迫显著降低了水稻种子发芽率、发芽势和发芽指数,分别为12.36%、52.18%和36.99%;水稻幼苗根系生长被显著抑制,幼苗叶片的丙二醛(MDA)显著含量增加67.41%,SOD、POD和CAT含量均显著降低,幼苗叶片的可溶性糖含量提高38.47%,蔗糖磷酸合成酶(SPS)活性增加了15.84%,而蔗糖合成酶(SS)活性则显著下降37.19%。利用纯水及各质量浓度CTS引发处理均不同程度缓解盐胁迫对种子萌发的抑制,提高了各项发芽指标,促进了水稻幼苗及根系的生长;与S-CK相比,各引发处理均显著提高了叶片中SOD(28.89%~53.99%)、POD(21.27%~50.33%)和CAT(62.88%~81.19%)活性,显著降低丙二醛含量(15.53%~28.79%),提高了幼苗可溶性糖含量、SPS与SS活性。【结论】利用CTS引发可有效改善盐胁迫下水稻种子的萌发、幼苗相关的糖代谢进程,通过去除活性氧、缓解渗透压,增强水稻幼苗抗逆性,可提高幼苗根系的生长状况,其中以100 mg/L壳聚糖效果最佳。

[Objective]Salt stress is one of the dominant stresses affecting crop growth and yield.In this study,the effects of chitosan(CTS)priming on rice seed germination and seedling growth under salt stress were investigated to identify the best priming treatment for rice to resist salt stress,which is of vital significance for ensuring food security.[Method]Wandao 16 was used as the study material,and 100 mmol/L NaCl solution was used to simulate salt stress.0(H_(2)O),50,100,150,200,and 250 mg/L CTS solution were set to prime rice seeds.The unprimed treatment without salt stress was adopted as control group 1(CK),and the unprimed treatment with salt stress was as adopted as control group 2(S-CK).The germination indicators of rice and the growth conditions of root and seeding,as well as antioxidant enzyme activities and glucose metabolism indicators were measured.[Result]The results showed that under salt stress,relative to CK,the germination rate,germination potential,and germination index of rice seeds decreased significantly by 12.36%,52.18%,and36.99%,respectively,and the root growth of rice seedlings was significantly inhibited.The content of malondialdehyde(MDA)in seedling leaves increased by 67.41%,the content of antioxidant enzymes significantly decreased,the content of soluble sugar in leaves of seedlings increased by 38.47%,the activity of sucrose phosphate synthase(SPS)increased by 15.84%,and the sucrose synthase(SS)activity decreased significantly by37.19%.H_(2)O and different concentrations of CTS priming treatments alleviated the inhibition of salt stress on seed germination,improved various germination indicators,and promoted the growth of rice seedlings and roots.Compared with S-CK,each treatment significantly increased the activities of SOD(28.89%-53.99%),POD(21.27%-50.33%),and CAT(62.88%-81.19%) in leaves,significantly decreased the content of MDA(15.53%-28.79%),and increased the soluble sugar content,SPS activity and SS activity of seedlings.[Conclusion]CTS priming effectively improved the germination of rice seeds under salt stress,improved the growth status of seedling roots,and ensured the sugar metabolism process related to rice seedlings.Therefore,CTS priming can enhance the stress resistance of rice seedlings by removing reactive oxygen species and relieving osmotic pressure,among which 100 mg/L chitosan achieves the best effect.