一氧化氮处理对马铃薯采后块茎愈伤的促进及机制

Effect and Mechanism of Postharvest Nitric Oxide Treatment on Promoting Wound Healing in Potato Tubers

目的:研究一氧化氮(nitric oxide,NO)处理对马铃薯块茎愈伤的影响,探讨其机理。方法:以‘陇薯7号’马铃薯块茎为试材,人工模拟损伤后,用0.5 mmol/L NO供体硝普钠(sodium nitroprusside,SNP)溶液浸泡损伤块茎10 min,于常温黑暗条件下进行愈伤处理。测定愈伤期间损伤块茎的质量损失率和Fusarium sulphureum损伤接种块茎的病情指数,观察愈伤期间损伤块茎伤口处软木脂和木质素的积累情况,分析伤口处组织苯丙烷代谢情况、过氧化物酶活性以及H_2O_2含量。结果:NO处理有效降低了愈伤期间损伤块茎的质量损失率和损伤接种块茎的病情指数,愈伤第7天时,SNP处理组块茎的质量损失率和病情指数比对照组分别低43.5%和27%。NO处理促进了块茎伤口处聚酚软木脂、聚酯软木脂和木质素的积累,愈伤第7天,处理组块茎的聚酚软木脂、聚酯软木脂和木质素细胞层厚度分别比对照组高25.2%、27.3%和23.6%。NO处理还显著提高了块茎伤口处组织苯丙氨酸解氨酶活力,增加了总酚、类黄酮和木质素的积累,愈伤第14天,处理组块茎PAL活力和总酚、类黄酮、木质素含量分别比对照组高75.3%、31%、39.6%和32.8%。此外,NO处理还显著增加了块茎伤口处的过氧化物酶活力和H_2O_2含量(P<0.05)。结论:NO激活了马铃薯块茎伤口处组织的苯丙烷代谢,提高了过氧化物酶活力和H_2O_2含量,加速了伤口处软木脂和木质素的积累,从而促进了马铃薯块茎的采后愈伤。

Objective:To study the effect of postharvest nitric oxide(NO)treatment on wound healing in potato tubers,and to partially explore the underlying mechanism.Methods:Potato tubers of the cultivar‘Longshu 7’were artificially wounded,dipped with sodium nitroprusside(SNP)as an exogenous donor of NO at 0.5 mmol/L for 10 minutes,and then allowed to heal at ambient temperature in darkness.The mass loss rate of wounded tubers and the disease index of those inoculated with Fusarium sulphureum were measured during the healing period,and the accumulation of suberin and lignin was observed in the wounds.Phenylpropanoid metabolism and peroxidase activity as well as H2O2 content in the wounds were also analyzed.Results:The mass loss rate of wounded tubers and the disease index of inoculated tubers were significantly reduced by NO treatment during healing period,which were 43.5%and 27%lower than that of the control on day 7 of healing.The treatment accelerated the accumulation of polyphenol suberin,polyaliphatic suberin and lignin,increasing the thickness of the polyphenol suberin,polyaliphatic suberin and lignin layers by 25.2%,27.3%and 23.6%relative to the control on day 7,respectively.Also,the treatment increased phenylalanine ammonia-lyase activity,and the contents of total phenols,flavonoids and lignin in the wounds by 75.3%,31%,39.6%and 32.8%compared with those of the control on day 14,respectively.In addition,NO increased significantly peroxidase activity and hydrogen peroxide content(P<0.05).Conclusion:NO treatment can activate phenylpropane metabolism,improve peroxidase activity and H2O2 content,and accelerate suberin and lignin accumulation in the wounds,thereby promoting wound healing in potato tubers.