Transcriptome Analysis and Morphological Changes in Response to Waterlogging in Iris pseudacorus

Iris pseudacorus is a widely cultivated and studied ornamental plant with a large biomass,strong adaptability and extensive management.Moreover,it has the ability to decontaminate and enrich heavy metals.However,few studies have been conducted on its submergence tolerance with little known about the molecular response of I.pseudacorus to flooding.Morphologically,I.pseudacorus had strong adaptability to waterlogging,the aerenchyma was gradually enlarged and adventitious roots developed between 0 and 14 d.The transcriptome data showed that the differentially expressed genes counts in plants flooded for 2 h,4 h,12 h and 24 h compared with the unflooded controls were 3555,9439,10734,and 4997,respectively.For GO term entries enriched by different genes,many biological processes,cell components and molecular processes in the I.pseudacorus roots were affected by flooding stress.Pathways enrichment analysis showed DEGs involved in hormone signal transduction pathways,glucose metabolism,glycolysis,and fermentation.The quantitative real-time PCR analysis of DEGs was basically consistent with the trend of transcriptome data,indicating reliability of the transcriptome data.The transcriptome analysis showed that formation of aerenchyma and adventitious roots was mainly induced by IAA(auxin)and accompanied by other hormone signals.Energy production was the primary coping mechanism of I.pseudacorus when aerenchyma was not sufficiently enlarged under water flooding.These results laid a foundation for further study on the mechanism of submerging-tolerance of I.pseudacorus and other aquatic plants.