摘要：

为研究盐胁迫下壳聚糖促进菜用大豆结瘤机制,探讨了NaCl胁迫下外源壳聚糖对菜用大豆蔗糖代谢及其在根部积累的影响。以菜用大豆品种日本青-快生型根瘤菌HH103共生体为试验材料,采用人工气候箱培养,分析NaCl胁迫下壳聚糖对菜用大豆结瘤与叶、根蔗糖和还原糖积累及蔗糖代谢相关酶活性的影响。结果表明,NaCl胁迫(T2)导致菜用大豆根瘤数、根瘤鲜质量显著(P<0.05)下降,各胁迫时期的平均降幅分别达36.06%和29.91%;使叶和根的蔗糖含量显著(P<0.05)升高、还原糖含量显著(P<0.05)下降;使叶和根的蔗糖合成酶(SS)、蔗糖磷酸合成酶(SPS)活性升高,中性转化酶(NI)、酸性转化酶(AI)活性下降。壳聚糖处理(T3)后,根瘤数和根瘤鲜质量在各胁迫时期均显著(P<0.05)升高,平均增幅达T2的26.87%和25.63%;叶、根蔗糖、还原糖含量以及蔗糖代谢相关酶活性均较T2显著(P<0.05)升高,其中叶、根的蔗糖和还原糖含量在各时期的平均增幅分别为11.32%,21.32%和10.22%,11.11%。壳聚糖可通过诱导NaCl胁迫下菜用大豆叶、根蔗糖代谢高水平运转,促进蔗糖向根部转移,进而促进结瘤,这可能是壳聚糖提高NaCl胁迫下菜用大豆结瘤能力的重要原因之一。

关键词: 菜用大豆, NaCl胁迫, 壳聚糖, 蔗糖代谢, 结瘤

Abstract:

To investigate the mechanism of chitosan promoting nodulation in vegetable soybean under salt stress,the effects of exogenous chitosan on sucrose metabolism and root accumulation in vegetable soybean under NaCl stress were explored.Effects of chitosan on nodulation,the accumulation of sucrose and reducing sugar in leaves and roots,as well as sucrose metabolism-related enzyme in vegetable soybean under NaCl stress were studied by using the vegetable soybean variety Nippon Green and the fast-growing rhizobia HH103 symbiosis as the test material in an artificial climate chamber.The results showed that the number of root nodules and fresh weight of root nodules in vegetable soybean were significantly decreased under the NaCl stress(T2)(P<0.05),with an average decrease of 36.06% and 29.91% in each stress period,respectively;the sucrose content of leaves and roots was significantly increased(P<0.05),and the reducing sugar content was significantly decreased(P<0.05);and the activities of sucrose synthase(SS)and sucrose phosphate synthase(SPS)were increased,while the activities of neutral convertase(NI)and acid convertase(AI)were decreased.The number of root nodules and fresh weight of root nodules significantly increased(P<0.05),after chitosan treatment(T3)in all stress periods,with average increases of 26.87% and 25.63% of T2;the sucrose and reducing sugar contents and sucrose metabolism-related enzyme activities of leaves and roots increased significantly compared with T2(P<0.05),with average increases of 11.32%,21.32% and 10.22%,11.11%,respectively.That chitosan could promote the nodule formation of vegetable soybean by inducing the high level of sucrose metabolism in the leaves and roots under NaCl stress and accelerating the transfer of sucrose to roots,which may be one of the important reasons for chitosan to improve the nodule formation ability of vegetable soybean under NaCl stress.

Key words: Vegetable soybean, NaCl stress, Chitosan, Glucose metabolism, Nodulation