拟康氏木霉胞壁多糖对黄瓜抗病性的诱导作用

为了更全面地认识拟康氏木霉菌（Trichoderma pseudokoningii SDTP1）的抗病机理，为该菌的开发和科学的施用提供依据，通过灌根处理和人工接病的方式研究了拟康氏木霉菌胞壁多糖（TPWS）对黄瓜幼苗抗病性的诱导作用。结果表明用浓度为200mg／L的TPWS处理后对人工接种尖镰孢分生孢子悬液的黄瓜幼苗的保护作用达到53．8％，浓度进一步提高保护作用升高不明显；用200mg／L的TPWS处理后，黄瓜幼苗下胚轴内苯丙氨酸解氨酶（PAL）和多酚氧化酶（POD）的活性及木质素的含量分别于6、30、30h后开始迅速升高，最高值时分别是对照的2．2、3．1、4．4倍；用200mg／L的TPWS处理后需要4d黄瓜幼苗才能表现出抗病性，不仅降低了伤根接种尖孢镰刀菌分生孢子悬液幼苗的枯萎病发病率，也能降低在茎部和叶面穿刺接种灰葡萄孢分生孢子悬液幼苗的灰霉病发病率。而TPWS在体外对两种病原菌无抑制作用，我们认为经处理的幼苗枯萎病和灰霉病发病率的降低与TPWS诱导了幼苗的抗病性有关，且这种抗性是系统的、非特异性的。抗病性可能与木质素含量的升高有关。

Study on Disease Resistance of Cucumber Induced by Cell Wall Polysaccharides from Trichoderma pseudokoningii

The solution of Trichoderma pseudokoningii cell wall polysaccharides(TPWS) was used to apply to the roots for the sake of studying the mechanism of the biological control of plant diseases of Trichoderma pseudokoningii. Results indicated that the TPWS of all concentrations tested could protect the seedlings against the wilt and the efficacy depends on the concentration. 200 mg/L TPWS provided 53.8% protection,but when the concentration up to 400 and 600 mg/L no further protection was observed. PAL and POD activities and lignin deposition in hypocoryls increased rapidly 6,30, 30 h after treatment with 200 mg/L TPWS, respectively. The inoculation tests before and after treatment showed that it took 4 d after the treatment for the seedlings to acquire resistance to the fusarium wilt. Otherwise, the treated seedlings also showed resistance against grey mould when conadia of Botrytis cinerea were inoculated on stem and leaves 4 d after the treatment. As TPWS of different concentrations did not inhibit the growth of mycelial of Botrytis cinerea and Fusarium oxysporum in vitro, it was inferred that the disease controlling effects of TPWS were attributed to induced resistance of plant,and the resistance was systemic and unspecificity. We assume that PAL and POD might result in lignification and thus be associated with the defense against the diseases.