二月兰种带真菌致病性研究

Pathogenicity of seed-borne fungi of Orychophragmus violaceus

二月兰是重要的地被、景观和绿肥作物。通过种子、离体叶片和温室盆栽试验,对分离自二月兰种子的链格孢菌,芸薹生链格孢,细极链格孢,黑附球菌,变红镰刀菌,顶孢哈氏霉,细基格孢属等5属7种可培养真菌进行了致病性测定。结果表明,7种真菌可致二月兰种子萌发后烂种烂芽率16.50%~68.50%,其中芸薹生链格孢、顶孢哈氏霉可引致种子发芽率降低18.18%~27.27%。7种种带真菌分别引致二月兰离体叶片出现褪绿和坏死腐烂等症状,发病率100%,病斑面积8.84%~99.38%,病情指数22.50~95.00。盆栽条件下,种带真菌均可致植物出现萎蔫褪绿和坏死叶斑等症状,病株率100%,叶片发病率41.56%~79.88%,病情指数16.22~56.93。与对照(不接种带真菌)相比,种带真菌侵染二月兰植株后第9天植物丙二醛(MDA)含量增加30.40%~204.15%,过氧化物酶(POD)活性变幅为-1.81%~82.87%,超氧化物歧化酶(SOD)活性升高18.78%~86.14%,叶绿素含量(SPAD值)降低13.24%~37.85%。致病性试验表明,芸薹生链格孢致病性最强,顶孢哈氏霉致病性最弱。

Orychophragmus violaceus is an important ground cover,landscape,and green manure crop species.Seven species of seed-borne fungi in five genera were isolated from the seeds of O.violaceus,and their pathogenicity was determined in seed germination,in vitro leaf inoculation,and greenhouse potted plant tests.The seed-borne fungi were Alternaria alternata,Alternaria brassicicola,Alternaria tenuissima,Epicoccum nigrum,Fusarium incarnatum,Harzia acremonioides,and Ulocladium sp.The percentages of seed rot and seedling rot caused by the seed-borne fungi ranged from 16.50%to 68.50%.A.brassicicola and H.acremonioides caused the seed germination percentage to decrease by 18.18%-27.27%.All the fungi caused symptoms such as chlorosis and leaf rot when inoculated onto O.violaceus leaves in vitro:the disease incidence was 100%,the lesion area was 8.84%-99.38%,and the disease index was 22.50-95.00.In potted greenhouse-grown O.violaceus plants,the seed-borne fungi caused wilt,chlorosis,leaf spot,or leaf rot symptoms.The percentage of diseased seedlings was 100%,the diseased leaf rate was 41.56%-79.88%,and the disease index was 16.22-56.93.We compared various biochemical indexes between control plants(not inoculated with seed-borne fungi)and those infected with seed-borne fungi at 9 days after inoculation.Compared with the control plants,the infected plants showed 30.40%-204.15%increases in malondialdehyde content,-1.81%-82.87%and 18.78%-86.14%increases in peroxidase and superoxide dismutase activities,respectively,and 13.24%-37.85%reductions in SPAD value.The results of the pathogenicity tests showed that A.brassicicola and H.acremonioides had the strongest and weakest pathogenicity against O.violaceus,respectively.