Systemic Induction Of Several Important Defense Enzymes In Rice With Zhongshengmycin

Zhongshengmycin was an agricultural antibiotic manufactured by microbiological fermentation. It had good effect on the plant bacterial diseases such as rice bacterial leaf blight(BLB),causing by Xanthomonas oryzae pv. oryzae (Xoo). The field trial for BLB showed that Zhongshengmycin had better protection than chemical pesticides, while the cure effect was less than chemical pesticides. Resistant strains of Xoo were not found in the field used Zhongshengmycin for several years. We presumed that Zhongshengmycin had inhibition to pathogens and probably improved the resistance of plant as well.Suspension-cultured cells of resistant and susceptible near-isogenic rice lines was established as study system. The transcript accumulation of Phenylalanine ammonia-lyase gene(pal), peroxidase gene(po), chalcone synthase gene(chs) and isoenzymes of PO, polyphenol oxidase(PPO) in suspension-cultured cells treated with Zhongshengmycin were studied. The relation of activity of PO, PPO, PAL in rice treated with Zhongshengmycin to control efficacy was studied. All these endeavor tried to elucidate the action mechanism of Zhongshengmycin comprehensively.The suspension-cultured cells of susceptible line Shennong 1033 and CBB4 carrying resistant gene Xa-4 near-isogenic line were Established for studying the expression of rice defense genes.The propagation of Xoo was strongly inhibited in rice suspension-cultured cells treated with Zhongshengmycin. The colony-forming unit of Xoo in rice suspension-cultured cells was 105 times as many as the treatment with Zhongshengmycin in 7d. The colony-forming unit of Xoo in susceptible shennong 1033 was about 10 times as many as the resistance CBB4. The results showed that the resistance of cultivars was relative to its inhibition to Xoo.The transcript accumulation of po, pal and chs in rice suspension-cultured cells could be induced by Zhongshengmycin, Zhongshengmycin+Xoo or Xoo. Quick, sustainable and an amount of transcript accumulation of po, pal and chs was found in resistance CBB4 comparing with susceptible Shennong 1033 when they were inoculated with Xoo. The transcript accumulation of po, pal and chs in cells treated with Zhongshengmycin orZhonghshengmycin+Xoo, was quicker and sustainable, than those in cells inoculated with Xoo, and the more amount of transcript accumulation was observed in treatments.Electrophoretic isoenzyme zymogram patterns of PO, PPO in rice suspension-cultured cells treated with Xoo and with Zhongshengmycin were studied. PO and PPO zymogram were 3 area in CBB4 and shennongl033, but CBB4 had more b2 PO band and less bl PPO band than shennong 1033. The b2 band was disappeared when CBB4 cells was inoculated with Xoo and the b2 appeared in Shennong 1033 when it was treated by Zhongshengmycin. It was presumed that b2 may be relative to rice resistance to Xoo.The action of Zhongshengmycin on the activity of PO, PPO and PAL in rice shoots, rice seedlings and mature rice was studied. The results showed that the activity of defense enzymes in shoots of highly resistance 2RCBB which seeds was soaked with Zhongshengmycin, increased mostly in 24h inoculating with Xoo. The activity of defense enzymes in the seedlings which seeds soaked and sprayed with Zhongshengmycin at 3-4 leaf and 5d before transplant, increased mostly in 24h inoculating with Xoo, was middle resistance CBB7. The activity of defense enzymes in mature rice, treating with Zhongshengmycin as seedlings, was enhanced much in Fengjing. The control efficacy of Zhongshengmycin to BLB was positively correlation to the activity of defense enzymes enhanced in seedlings and mature rice. These results demonstrated that the action mechanism of Zhongshengmycin was to enhance the activity of defense enzymes in riceThe severity of BLB could be decreased by early Zhongshengmycin treatment. The control efficacy of Zhongshengmycin to BLB, with clip inoculation in numerous Xoo, was 58.4% for middle resistance Fengjing, and following were susceptible Jingang 30,andhighly resistance CBB7.All the results demonstrated that the good control e...