Molecular Mechanism Research On The Responses Of Rice (Oryza Sativa L.) To Xanthomonas Oryzae Pv.oryzicola Infection

Rice bacterial leaf streak (BLS) caused by the pathogen Xanthomonas oryzae pv. oryzicola (Xooc) is one of the major rice diseases in South China. It leads to decreased rice production generally by 15-25%, even by 40-60% in prevailing years. So it's necessary to further understand the pathogenesis of Xooc, the resistant genetic mechanism in rice and the molecular basis of the interactions between Xooc and rice, to illustrate molecular ecological mechanism on the resistance gene expression induced by Xooc, which will play important roles in controlling BLS epidemics and reducing economic losses.The pathogen Xooc with strong pathogenicity in South China was used to inoculate the callus derived from the seed embryo of rice cultivar JiaFuZhan(Oryzae sativa L.) via single seed descendant. mRNA differential display (DD) was used to analyse the related resistant gene expression induced by Xooc. Sixty DD fragments were detected, of which fifty were specifically expressed in the rice callus induced by Xooc, another ten were suppressed expression in the control. And four positive clones were identified after recovering and blotting with RDB(reverse dot-blotting) for these DD cDNAs. In comparison with rice genome sequences in NCBI GenBank, four positive clones,24-21,39-34,45-11 and 55-34 were mapped on the nbeb0039C14 clone(GenBank Acc:AC087549) of chromosome 10,the BAG clone OSJNBb0086G17(GenBank Ace: AC144455) of chromosomes, the P0410E03 clone (GenBank Acc:AP002844)of chromosomel and the OSJNBa0060A14 c!one(GenBank Acc:AC021893)of chromosome 10, respectively.In comparison with the EST library, 24-21 sequences showed 97% identical and expectation value of 3e-82 with a rice root cDNA ID 1561 (GenBank Acc:BE607423) stressed by NaCl, and also 9% homologies to a Bombyx mandarina cDNA H109(GenBank Acc:AT001109). However, 39-34 sequences contained a cDNA OML00455(GenBank Acc:CB210175) from Oryza minuta HybriZAP-2.1 XR library and were partially identical with both two cDNAs, OSJNEb09A05 (GenBank Acc:CB646488)and OSJNEb09B24 (GenBank Acc:CB646568)induced by Magnaporthe grisea, a cDNA E2428 (GenBank Acc:AU094102) from rice panicle at flowering stage, a cDNA E60992 (GenBank Acc:AU095268) from rice immature leaf under short day condition and a cDNABR030002000_PLATE_Ell₈5₀86.abl (GenBank Acc:CA754595) from rice root stressed by NaCl. The nucleic acid sequences of 45-11 also were highlightedly homologous with a waterlogged barley root cDNA EBro03_SQ005_D03 (GenBank Acc:BQ763644), a barley embryo cDNA S0000200030A08F1 (GenBank Acc:AJ434386) 1 day after pollination, a rice cDNA V001A03 (GenBank Acc:BM421151) induced by Magnaporthe grisea, a subtracted cDNA Rxo-2_B05 (GenBank Acc:CA452438) from maize inbred line B73 infected withX.oryzaepv. oryzicola strain BLS222 and a subtracted cDNA Rp3A-2_F03 (GenBank Acc:CA452784) from maize inbred line H95-Rp3A inoculated with Puccinia sorghi isolate INI. 55-34 clone showed highly similar to a waterlogged barley root cDNA EBro03_SQ008₁17 (GenBank Acc:BQ765947), a Sorghum bicolor embryo 1 cDNA EMl₅2_H05.gl_A002(GenBank Ace: BG464036),a cDNA Ta02₁3g08 (GenBank Acc:BQ901614)of wheat inoculated with Fusarium graminearum, a cDNA wlm0.pk041.o7(GenBank Acc:CA658271) from wheat after inoculation with Erysiphe graminis and also had 417bp identical with a cDNA EOS 16 (GenBank Ace: AU172440) from rice panicle at flowering stage.With the aid of BLAST algorithm, the results demonstrated that 24-21 cDNA encoded a new amino acid sequence. But the amino acid sequence encoded by 39-34 cDNA had 34 amino acid identities with the ATI (GenBank Acc:S57459), and also had partial similarities to Staphylococcus aureus transfer complex protein TrsE(GenBank Ace: F36891),and NADH dehydrogenase subunit4(GenBank Acc:AAK70514). However, the putative amino acid sequence from 45-11 cDNA showed only homologous with PDR-like ABC transporter (GenBank Acc:CAD59568). It could be inferred that the amino acid sequence encoded by 55-34 cDNA exhibited 98% identical and positived with putative pectin methylesterase (...