草酸青霉线性五肽生物合成的比较转录组分析

Comparative Transcriptome Analysis of Linear Pentapeptide Biosynthesis in Penicillium oxalicum

摘要:

草酸青霉（Penicillium oxalicum）是一种重要的植物生防菌，从三峡河岸带分布的草酸青霉中，分离到一种线性五肽，该物质对柑橘致腐菌指状青霉（P. digitatum）具有极强的抑制作用。为了分析该五肽的生物合成机制，本研究采用BGISEQ-500平台，测定了3株不同五肽含量的草酸青霉（114-2，SG-4，SJ-3）cDNA文库，并使用参考基因组对序列进行了比较。高通量测序结果表明，3株草酸青霉平均产出了6.55 GB的序列数据，与有参转录组的平均比对率达到91.65%。差异表达基因比较分析表明，相较于不产五肽的114-2，在生产五肽的SG-4和SJ-3中，共有1 648个基因上调表达，1 251个基因下调表达。AntiSMASH分析表明，在草酸青霉基因组中可能存在33个非核糖体肽合成酶（NRPS），其中15个NRPS的表达与五肽物质的变化趋势一致。进一步的RT-PCR表达分析表明，基因簇PDE_01071可能是负责五肽合成的基因簇。

Abstract:

Penicillium oxalicum is an important biocontrol microbe in plants. A linear pentapeptide was isolated from P. oxalicum distributed in the Three Gorges river bank, and it had an extremely strong inhibitory effect on P. Digitatum, a pathogen causing citrus rot. In order to explore the biosynthesis mechanism of linear pentapeptide, the cDNA libraries of three P. oxalicum strains (114-2, SG-4, SJ-3) with different pentapeptide contents were sequenced by the BGISEQ-500 platform, and the results were compared with the reference transcriptome. High-throughput sequencing produced 6.55 GB of data averagely, and the alignment rate with the reference transcriptome reached 91.65%. Compared with 114-2 without pentapeptide production, comparative analysis of differentially expressed genes showed that a total of 1 648 genes were up-regulated and 1 251 genes were down-regulated in SG-4 and SJ-3 that could produce pentapeptide. AntiSMASH analysis suggested that there might be 33 non-ribosomal peptide synthetases (NRPS) genes in P. oxalicum genome, among which the expression of 15 NRPS was consistent with that of pentapeptide. Further RT-PCR expression analysis showed that the gene cluster PDE_01071 might be responsible for pentapeptide synthesis.