赤星菌弱毒株TBA16对烟草抗赤星病诱导作用条件的研究

IMPROVEMENT OF CONDITIONS FOR INCREASING EFFECTS OF THE WEAK STRAIN TBA16 OF THE PATHOGEN (ALTERNARIA ALTER-NATA) TO INDUCE TOBACCO RESISTANCE TO BROWN SPOT

用病菌弱毒株TBA16的孢子按4种方法对烟苗进行诱导处理时,叶面喷洒和叶面悬滴诱导处理法可以明显地诱导烟草对赤星病的系统抗性。在叶面悬滴诱导中,诱导抗性在第6天开始表现,第12天达到最高并持续到第21天。重复诱导可使诱导抗性持续期延长,并使抗性程度提高,经3次重复诱导后抗性诱导效应可以由36％-83％提高到100％,4次重复诱导使抗性持续期由21天延长到42天以上。诱导抗性表现程度还与挑战按种后的保湿时间有关,并明显地受温度影响,在24℃左右抗性诱导效应最高,在30℃和16-20℃下效应减弱51.3％-56.4％。病菌毒素诱导比孢子诱导的效果高35％-77％,用叶面悬滴法诱导时,毒素的抗性诱导效应最高可达到100％。

The weak virulence strain TBA16 of Alternaria alternata was tested for its function of inducing tobacco resistance to brown spot by 4 methods of induction inoculation with conidial suspensions. The leaf spray method and leaf droplet method gave good effects when the chall enge inoculation with the virulent strain TBA28 was conducted after 6 days of induction treatments. In the treatment with droplet inoculation method, the systemic resistance of the plant expressed at 6 days, reached peak at 12 days, and lasted 21 days after inducing inoculation. The plants were induced repeatedly at 6 and 12 days after the last in- duction, respectively, which resulted in increasing induced resistance from 36%-83% up to 100% by 3 times of induction, and in lasting expression of induced resistance from 21 days to more than 42 days by 4 times of inducing inoculation. The extension of expressing induced resistance was affected by the lasting time of high moisture of the challenge inoculated plants and by the temperature during resistance inducing treatment. The resistance appeared higher at about 24℃ and de- creased by 51.3%-56.4% under 16-20℃ and 30℃. The fungal toxin was also used as resistance inducer with the above mentioned 4 meth- ods of induction treatment and proven to be able to induce 100% sys- temic resistance of tobacco seedlings to brown spot by leaf droplet inoc- ulation method, which was 35%-77% higher than that induced by the spore of the same fungal strain.