The Transcript Accumulation Of Several Important Defense Genes In Suspension-cultured Cells Of The Near-isogenic Rice Lines Treated By Zhongshengmycin

Zhongshengmycin (a new, commercially available agricultural antibiotic from 1996) has been widely utilized for controlling plant diseases, particularly on bacterial diseases. However the mode of action of Zhongshengmycin do not completely be understood. The previous research had discovered that Zhongshengmycin was less to inhibit the growth and reproduction of Xanthomonas oryzae pv. oryzae (Xoo) than chemical pesticides, but Zhongshengmycin protected Xoo infection to rice better than chemical pesticides. In addition, the resistance of plant pathogens to Zhongshengmycin is not found up to now. In order to settle the query, temporal accumulation of several important defense gene transcripts in suspension-cultured cells of the near-isogenic lines for bacterial blight resistance of rice was detected.The results showed that genetic trait of rice and quantity of 2,4-D were the key elements to callus induction from mature rice seeds and suspension culture of rice cells. The procedure of callus induction from mature rice seeds and suspension culture of rice cells was set up.Kinetics of Xoo multiplication in rice suspension cells was studied. The quantity of Xoo multiplication was obviously less in the rice suspension cells of resistant rice cultivar CBB4 than in the rice suspension cells of susceptible rice cultivar Shennong 1033. The result indicated that inhibition of Xoo multiplication in the rice suspension cells was related to rice resistance to Xoo.The transcripts of PO, PAL and CHS genes, three defense genes encoding respectively peroxidase (PO), phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) in suspension-cultured cells of the near-isogenic lines for bacterial blight resistance of rice were discovered during interactions with Xoo. Northern blot analysis showed that the accumulation of PO, PAL and CHS gene transcripts in susceptible rice cultivar Shennong 1033 was generally delayed, attenuated and lasted for a shorter period of time as compared with the accumulation of PO, PAL and CHS gene transcripts in resistant rice cultivar CBB4. The accumulation of PO, PAL and CHS gene transcripts in suspension-cultured cells of the near-isogenic lines for bacterial blight resistance of rice was positively related to rice resistance to bacterial blight disease, and was analyzed as the indicator of rice resistance to bacterial blight disease.The transcripts of PO, PAL and CHS genes in suspension-cultured cells of the near-isogenic lines for bacterial blight resistance of rice were detected during interactions with Zhongshengmycin. Northern blot analysis suggested that theABSTRACTbactericide Zhongshengmycin could greatly strengthen PO, PAL gene transcripts in the rice suspension cells of susceptible rice cultivar Shennong 1033 and resistant rice cultivar €884 regardless of the presence or absence of Xoo. During interactions with Zhongshengmycin, the accumulation of PO and PAL gene transcripts in the rice suspension cells of susceptible rice cultivar Shennong 1033 and resistant rice cultivar €884 was markedly a higher level than interactions between rice and Xoo. In addition, the bactericide Zhongshengmycin could greatly strengthen CHS gene transcripts in the rice suspension cells of susceptible rice cultivar Shennong 1033 regardless of the presence or absence of Xoo, while the transcripts of CHS gene in the rice suspension cells of resistant rice cultivar CBB4 accumulated moderately in response to Zhongshengmycin regardless of the presence or absence of Xoo. Interestingly, during interactions with Zhongshengmycin all these transcripts of PO, PAL and CHS genes in suspension-cultured cells of the near-isogenic lines for bacterial blight resistance of rice accumulated to a higher level than the interactions between rice and Xoo regardless of the presence or absence of Xoo.The findings of this study demonstrated that Zhongshengmycin could not only inhibit the growth and reproduction of Xoo, but also induce the accumulation of PO, PAL and CHS gene transcripts in suspension-cultured cells of th...