番茄Ph-2基因晚疫病株龄抗性的比较转录组分析

Comparative Transcriptome Analysis of Age-related Resistance of Ph-2 Gene to Late Blight(Phytophthora infestans)in Tomato

晚疫病是危害番茄的重要病害,研究表明番茄抗晚疫病Ph-2基因存在株龄相关抗性(age-related resistance,ARR)。通过对Ph-2基因晚疫病抗性材料三叶期与六叶期幼苗接种晚疫病菌后0、8、24、48 h的转录组比较分析,发现接种后0~48 h,Ph-2基因与其他典型抗病基因在三叶期与六叶期幼苗间表达量不存在显著性差异,而2个过氧化物酶活性基因Solyc01g006290与Solyc02g087110在不同苗期叶片中的差异表达可能是导致Ph-2基因晚疫病株龄抗性产生的主要原因,接种后0~48 h,Solyc01g006290基因在六叶期幼苗中表达量始终显著高于三叶期幼苗,该基因正调控木质素合成,并在细胞壁强化中起重要作用;接种后0 h,Solyc02g087110基因在三叶期与六叶期幼苗中表达量不存在显著性差异,而接种后8~48h三叶期幼苗中该基因表达量大幅下调并显著低于六叶期幼苗。此外,三叶期与六叶期幼苗水杨酸与乙烯信号转导途径中响应晚疫病抗性相关基因的表达也存在差异。研究结果为番茄持久抗晚疫病育种提供了一定依据。

Late blight is an important disease destroying tomato production.Previous studies have shown that Ph-2 gene presented age-related resistance against late blight in tomato.In this study,we used comparative transcriptome analysis to identify the differentially expressed genes at 0 h,8 h,24 h and 48 h respectively after inoculation of Phytophthora infestans between two seedling stages.The results showed that there was no significant difference in the expression levels of Ph-2 gene and other typical disease resistance genes between the three-leaf stage seedlings and the six-leaf stage seedlings at 0-48 h after inoculation.The expression difference of peroxidase gene Solyc01g006290 and Solyc02g087110 between the two seedlings maybe one of the causes for the age-related resistance.The expression level of Solyc01g006290 gene in six-leaf stage seedlings from 0-48 h after inoculation was always significantly higher than that in three-leaf stage seedlings.Solyc01g006290 gene positively regulates lignin synthesis and plays an important role in cell wall strengthening.There was no significant difference in the expression level of Solyc02g087110 gene between the three-leaf stage seedings and six-leaf stage seedlings at 0 h after inoculation,but the expression level of the gene in the three-leaf stage seedlings is greatly down-regulated and significantly lower than that in the six-leaf stage seedlings at 8-48 h after inoculation.Besides,the difference in the expression of genes in salicylic acid and ethylene signal transduction pathways between the two seedlings may also be one of the reasons for the age-related resistance.Our result lays the foundation for the durable resistant breeding against late blight in tomato.