Evaluation Of Waterlogging Tolerance Of Canna Plants And Its Response To Morphophysiological,Physiological And Gene Expression Differences Under Waterlogging Stress

Waterlogging is a kind of common abiotic stress,significantly affecting the growth and development of plant.Canna is a multi-function plant that had both food and ecological restoration capacity,which had various cultivars and was significantly different at the demand of water.However,the waterlogging tolerance in Canna lacks systematic evaluation,the mechanism of its waterlogging resistance was also unclear,which has led to the blind selection of Canna cultivars in cultivation practices and applications.In this study,we evaluated the waterlogging tolerance ability of 12Canna cultivars and selected the waterlogging resistant and waterlogging sensitive cultivars.On this basis,two Canna cultivars with different waterlogging tolerance ability were taking as materials,we explored the morphological and physiological response mechanism of Canna in response to waterlogging stress,and preliminarily screened the different expressed genes response to waterlogging stress by RNA-seq and q RT-PCR techniques,which laid a foundation for further explaining the molecular mechanism of canna response to flooding stress.The results are as follows:1.Using mathematical statistical methods such as principal components analysis,subordinate function analysis and cluster analysis to comprehenssively evaluate the waterlogging tolerance ability of 12 Canna cultivars.Results showed that the waterlogging tolerance ability of 12 Canna cultivars ranked from high to low is‘Mohong’,‘Ziye Xiaojuhong’,‘Grand Due’,‘Canna indica’,‘Suihua chenghong’,‘Lüyecheng’,‘Yellow Canna’,‘Xingyu-2’,‘Xingyu-1’,‘Qianbei jiaoyu’,‘Sajin’and‘PLRF’.According to the waterlogging tolerance ability,they are divided into four groups,containing waterlogging-tolerant group,intermediate waterlogging tolerant group and low waterlogging-tolerant group.2.Waterlogging stress significantly reduced the fresh and dry weight of Canna plants,and the damage of underground parts was more serious than that of the above.In addition,the fomation of adventitious roots and arenchyma of tow culticvars was promoted by waterlogging stress.And the caused the yellowing of the leaves of‘Qianbei jiaoyu’,as well as the blackening and decaying of the rhizomes and roots,shedding of roots.Moreover,waterlogging damaged the root cell organelles,which lead to the degradation of nucleus,mitochondria and endoplasmic reticulum.While there was no obvious damage phenomenon in‘Mohong’.3.Waterlogging stress leads to the continuous decrease of root vitality in two cultivars.The content of soluble protein and soluble sugar increased significantly in the early stage but decreased in the late stage.With the extension of waterlogging time,the content of MDA,H₂O₂and O₂^-.in leaves and roots increased relatively.Antioxidation and anaerobic respiratory enzyme activity increased significantly in the early stage which then declined.While aerobic respiratory enzyme continued to decrease and the metabolism of endogenous hormones disturbed.The content of osmotic regulation substances and the activities of antioxidant enzymes and anaerobic respiratory enzymes in‘Mohong’were significantly higher than those in‘Qianbei jiaoyu’,and the increase rate of reactive oxygen species was significantly lower in‘Mohong’.4.Under waterlogging stress,‘Mohong’responded more strongly at the transcription level than‘Qianbei jiaoyu’.The GO and KEGG results showed that the differential genes were mainly enriched in hormone signaling transduction pathway,MAPK signaling pathway,starch and sucrose metabolism,glycolysis/glyconeogenesis and antioxidant enzymes,etc.Ten major transcription factor families,including ERF,were annotated in this study,the family members of ERFs,including ERF071-like,RAP2-4,RAP2-9,and DREB3 were significantly induced by waterlogging in‘MH’,and the up-regulation degree was greater than that of‘Qianbei jiaoyu’.In addition,51genes significantly upregulated in at least one waterloging treatment time point were selected as candidate genes whose upregulated in‘Mohong’were higher than those in‘Qianbei jiaoyu’,which play an important role in waterlogging tolerance ability in Canna with different expression patterns.