中文摘要：

以黑松、马尾松和火炬松为研究对象,对其接种松材线虫后4,12,24,48,72,96和120h的NO和核酸酶的活性进行测定。3种松树接种松材线虫后,针叶内NO平均含量的积累为火炬松〈马尾松〈黑松,这种差异在12～48h尤为明显;48h后较其割伤处理（CK1）的增加幅度为火炬松〉马尾松〉黑松。同时3种松树接种后的核酸酶变化趋势存在差异,单链核酸酶活性在4～48h为火炬松〉马尾松〉黑松,而火炬松双链核酸酶活性在4～96h时却一直低于马尾松和黑松,这表明不同松树体内单链或双链核酸酶的活性变化与其抗病性有关。且3种松树在接种松材线虫后,表现出症状的时间顺序为黑松最早,马尾松次之,火炬松最晚。这表明NO和核酸酶的变化与松树感染松材线虫后的病程发展密切相关。

英文摘要：

To investigate the role of nitric oxide （NO） and nuclease in pine wilt disease, we examined NO content and nuclease activity in pine needles of Pinus taeda, P. massoniana, P. thunbergii inoculated with nematodes （Bursaphelenchus xylophilus） for 4, 12, 24, 48, 72, 96 and 120 h. The results showed that NO content in pine needles after the inoculation was P. taeda 〈 P. massoniana 〈 P. thunbergii, and this phenomenon was particularly evident at 12- 48 h after the inoculation; the increase range of NO content in pines compared to their treatment which inoculated with distilled water was ranked as P. taeda 〉 P. massoniana 〉 P. thunbergii at 48 h after the inoculation. Meanwhile, the nuclease activity was significantly different in pine species after inoculation of the nematodes. The activity of singlestranded nucleic acid enzyme was in a rank of P. taeda 〉 P. massoniana 〉 P. thunbergii at 4 - 48 h after inoculation, however the activity of double - stranded nucleic acid enzyme in P. taeda was lower than P. thunbergii and P. massoniana during 4 -96 h after inoculation. These results suggested that changes in activity of double-stranded nucleic acid or single-stranded nucleic acid enzyme in different pines were related to their resistance. The observation of symptoms showed that P. thunbergii first appeared wilt symptoms, followed by P. massoniana, and then P. taeda. The changes of NO content and. nucleic acid enzyme activity were closely related to the development of pine wilt disease symptoms.