内生真菌侵染对化感物质胁迫下木麻黄幼苗根系活性氧代谢及保护酶系统的影响

Effects of endophyte infection on reactive oxygen metabolism and protective enzyme system of Casuarina equisetifolia seedlings under allelopathic stress

本文对未侵染(EF)和侵染(EI)内生真菌(Phyllosticta sp.)的木麻黄幼苗分别进行5种提取自木麻黄根系的化感物质[12,13-dihydromicromeric acid、白桦脂酸、3-O-咖啡酰基羽扇豆醇、儿茶素和表儿茶素]胁迫,比较不同胁迫浓度和胁迫时间下内生真菌对木麻黄幼苗根系活性氧代谢以及保护酶系统的影响。结果表明:化感胁迫浓度、胁迫时间和内生真菌对木麻黄幼苗根系活性氧代谢(O^-·2产生速率、H2O2和MDA含量)和保护酶系统(CAT、POD和SOD活性)有交互作用。化感胁迫导致O^-·2产生速率、H2O2和MDA含量显著升高,CAT、POD和SOD活性显著升高后降低,达到峰值的时间提前。在较低浓度(12.5、25、50和100 mg·L-1)和较短时间(0~48 h)胁迫下内生真菌能够显著提高保护酶活性并抑制活性氧含量的增加(P<0.05)。随胁迫浓度和时间增加,内生真菌对木麻黄保护酶活性的促进作用受到抑制。化感物质种类影响木麻黄幼苗根系受伤害的程度,较低浓度(0~50 mg·L-1)和较短时间(0~36 h)胁迫下3-O-咖啡酰基羽扇豆醇对木麻黄伤害程度最大,儿茶素伤害程度最小;较高浓度(100~400 mg·L-1)和较长时间(48~72 h)胁迫下12,13-dihydromicromeric acid对木麻黄伤害程度最大,白桦脂酸伤害程度最小。

In this paper,five kinds of allelochemicals(12,13-dihydromicromeric acid,betulinic acid,3-O-coffee-acyl-lupeol,catechin and epicatechin)extracted from the roots of Casuarina equisetifolia were applied to C.equisetifolia seedlings of uninfected(EF)and infected(EI)endophyte(Phyllosticta sp.)and the effects of different stress concentrations and stress time on active oxygen metabolism and protective enzyme system in roots were compared.The results showed that there were interactions of allelopathic stress concentration,stress time and endophyte with active oxygen metabolism(O^-·2production rate,H2 O2 and MDA contents)and protective enzyme system(CAT,POD and SOD activities)of C.equisetifolia roots.Allelopathic stress led to a significant increase in O2-·production rate,H2 O2 and MDA contents(P<0.05),and a significant decrease after increase in CAT,POD and SOD activities(P<0.05),and reached the peak time earlier.Endophyte with low concentration(12.5,25,50,100 mg·L-1)and short time(0–48 h)stress could significantly increase the activities of protective enzymes and inhibit the increase of active oxygen content(P<0.05).With the increase of stress concentration and time,the promoting effect of endophyte on the protective enzyme activities of C.equisetifolia was inhibited.The type of allelochemicals affected the degree of damage to the roots.Under lower concentration(0–50 mg·L-1)and shorter time(0–36 h)stress,3-O-coffee-acyl-lupeol had the greatest damage to C.equisetifolia and catechin had the minimum damage.Under higher concentration(100–400 mg·L-1)and longer time(48–72 h)stress,12,13-dihydromicromeric acid had the greatest damage and betulinic acid had the minimum damage.