杧果与Fusarium mangiferae在转录水平上的互作机制

Interaction mechanism between mango and Fusarium mangiferae on transcriptomes

基于Illumina HiSeq^(TM)2000平台,对健康与感病杧果顶芽的转录组进行测序,采用BLAST软件将获得的Unigene与NCBI-nr、Swiss-Prot、KEGG和COG数据库进行比对,根据基因功能注释后分析杧果病健组织的差异表达基因(DEGs),并对DEGs进行GO和Pathway富集分析。结果表明:2个样品共获得119 815条Unigene,N50为1 546 bp,平均片段长度为880 bp;鉴定了29 878个DEGs,对随机挑选的11个差异表达基因进行了qRT-PCR验证,结果与转录组一致。以corrected P-value≤0.05为阈值的代谢途径有22条,其中大多数代谢途径与植物的抗逆响应密切相关;153个DEGs参与了淀粉和蔗糖代谢途径,DEGs主要是编码糖类异构酶、水解酶和转移酶等,参与葡萄糖水解、细胞碳水化合物、丙酮酸盐和核苷酸代谢等生物进程;在抗氧化生物过程中,编码活性氧代谢相关酶且log_2Ratio>10或<-10以上的DEGs有20个,14个属上调表达,表明活性氧代谢在杧果与病原互作过程中起到重要的调解作用;F.mangiferae侵染杧果后,以log_2Ratio>10或<-10为筛选条件,共获得酚类代谢相关差异表达基因53个,其中40个DEGs上调表达,推测杧果可能是通过合成加固细胞壁的木质素或生成抑菌作用的酚类化合物来提高对病原菌的抵抗能力;杧果与F.mangiferae互作过程中,钙信号传导、SA信号途径和丝裂原活化蛋白信号传导途径相关基因表达下调,造成了下游植物抗病基因RPM1的表达受到抑制,这可能是杧果畸形病的主要成因之一。

Using the Illumina HiSeqTM2000 platform,the transcriptomes of healthy and infected mango buds were sequenced. Through Blastx comparison to Nr、Swiss-Prot、KEGG and COG databases,functional annotations of the differentially expressed genes（DEGs） were obtained. The DEGs were then carried out GO and KEGG pathway analysis. The results showed that： a total of 119 815 unigenes was obtained from the two samples,with 880 bp in the average length and 1 546 bp in N50 value. Through the transcriptomes analysis with the RPKM（reads per kb per million reads method）,29 878 DEGs were acquired. Additionally,11 DEGs were chosen for qRT-PCR verification and the results were consistent to the RPKManalysis. Taking corrected P-value ≤0.05 as a threshold,DEGs were enriched in 22 pathways,most of which were closely related to stress responses.A total of 153 DEGs were involved in metabolism of starch and sucrose,most of which encode racemase and epimerase,hydrolase and intramolecular transferase and take part in the glucose catabolic process,carbohydrate metabolic process,pyruvate metabolic process,nucleotide metabolic process,and so on. In the antioxidant activity process,twenty DEGs that encoded enzymes involved in reactive oxygen metabolism were acquired withratio larger than ten and 14 DEGs were up-regulated. It demonstrated that reactive oxygen metabolism played an important role in the mango-Fusarium mangiferae interaction. With ratio larger than ten,fifty-three DEGs related to phenolic metabolism were acquired,forty of which were up-regulated. It indicated that mango may protect itself from the F. mangiferae infection by accelerating the synthesis of secondary substances,such as lignin and phenolic compounds. Calcium signal transduction pathways,salicylic acid（SA） pathway and mitogen-activated protein kinase（MAPK） signal pathways were down-regulated in the mango-F. mangiferae interaction. RPM1,an important gene related to plant disease resistance,was also down-regulated,which was probably the main reason to the susceptibility of mango to F. mangiferae.