Germplasm Identification And Baimaya Biological Analysis Of Waterlogging Tolerance At Seedling Stage In Maize

Waterlogging has become one of the major abiotic stresses to a variety of plants including maize in southern China.Investigating the biological characteristics of waterlogging tolerance,creating new waterlogging resistant maize germplasm and cultivating new waterlogging resistant maize varieties are the most economical and effective way to reduce the loss of maize yield.In this study,117 maize materials in Hubei province were identified for their waterlogging tolerance and a batch of waterlogging tolerance and extremely sensitive materials were identified.The morphology,physiology,molecular and other aspects of waterlogging tolerannce of Baimaya(BMY)were analyzed,which provided theoretical basis for further utilization of this resource.The main research results are as follows:1.Identification of waterlogging tolerance of 117 maize inbred lines: The grades of117 maize inbred lines were divided with waterlogging tolerance survival rate as evaluation index.A batch of water-resistant materials were identified.The survival rate of HA83050,BMY,HA83008 and H83123 was over 90% after 14 days of waterlogging.At the same time,this study also identified some extremely sensitive waterlogging materials,including HA83102,B73,HA83137,HA83139,HA83141,HA83149 and HA83185,which almost all died after 14 days of waterlogging.It laid the material foundation for the basic research and breeding of waterlogging resistant germplasm.2.At the phenotypic level: SPAD value,root and shoot fresh significantly higher than those of B73 waterlogging weight,root and shoot dry weight,seedling height,number of adventitious roots and root length of BMY were under stress.Under waterlogging stress,the difference of seedling height between B73 and BMY increased with the extension of treatment time,indicating that BMY had a strong tolerance to waterlogging.Compared with B73,BMY had developed adventitious roots under waterlogging stress and could induce aerenchyma formation rapidly.3.At the physiological and biochemical level: the malondialdehyde content in B73 increased significantly after 6 days of waterlogging,while BMY remained at a relatively low level.Moreover,the activities of peroxidase and superoxide dismutase increased and rapidly accumulated in the root system after waterlogging stress,indicating that BMY had strong scavenging ability of reactive oxygen species.4.At the Phosphorus uptake and utilization: Under normal growth and phosphorus deficiency treatment,the seedling weight,stem weight,root weight and root shoot ratio of BMY were significantly higher than that of B73,and the difference was more significant under low phosphorus condition.On the root number and root length,whether normal growth or low phosphorus condition,the BMY times the number and length of root were significantly higher than B73 under the normal growth and phosphorus deficiency treatment.The number and length of secondary roots of BMY were significantly higher than those of B73 under normal growth or phosphorus deficiency treatment.Under normal growth and phosphorus deficiency treatment,the content of phosphatase secreted by roots and acid phosphatase in tissues of BMY were higher than that of B73.Under the condition of phosphorus deficiency,the utilization capacity of BMY to phosphorus was significantly improved,and the strong phosphorus absorption capacity of BMY enhanced the ability to resist abiotic stress.5.Transcriptome sequencing analysis: a total of 7558 differentially expressed genes were detected in B73 and BMY after 7 days of waterlogging,among which 4720 genes were up-regulated and 2838 genes were down-regulated.The expression of genes related to ethylene and gibberellin was significantly up-regulated,which might be related to the waterlogging tolerance of BMY.