Evaluation Of Maize Kernel Dehydration Characteristics Of Inbred Lines And Its Relationship With Aquaporins

Maize kernel moisture content(KMC)greatly affects mechanical kernel harvest,which is an important direction of maize industry development.The KMC at harvest is mainly determined by the KMC at physiological maturity and the subsequent kernel dehydration rate(KDR).The germplasm evaluation of maize kernel dehydration characteristics is of great significance to maize germplasm improvement and utilization.Identification and improvement of mazie inbred lines with low KMC at physiological maturity and fast KDR can provide important germplasms for maize varieties suitable for mechanical kernel harvest.Plant aquaporins(AQPs)are widely involved in various processes of plant growth and development.However,roles of maize aquaporins(Zm AOPs)-mediated water transmembrane transport in maize kernel maturing drying remains largely unknown.In this study,48 maize inbred lines were used as materials to identify and evaluate their dehydration characteristics,and the relationship between Zm AQPs and maize kernel dehydration was clarified.This study provided important genetic and germplasm resources for maize germplasm improvement and utilization.The main results are as follows:1.Evaluation of kernel dehydration characteristics of maize inbred linesThe phenotypes of maize kernel dehydration-related traits(like kernel size,the proportion of keratin endosperm regions,and etc.)of natural population were identified,from which 48 maize inbred lines with extreme phenotypic traits were screened out.According to the cluster analysis of KMC＿PM(kernel moisture content at physiological maturity),AUDDC(area under the dry down curve)and KDR,two different indicators for kernel dehydration rates evaluation,the 48 maize inbred lines were divided into three categories,namely,excellent,medium and poor dehydration characteristics.Among them,10 germplasm materials such as huangyesi3,Mo17,and ziduosui showed excellent dehydration characteristics,while 17 germplasm materials such as Zheng58,DH351 and DH382 showed poor dehydration characteristics.2.Factors influencing the kernel dehydration characteristics of maize inbred linesThe correlation analysis of mazie kernel dehydration characteristics and physical and chemical characteristics of seeds and the related traits of ear showed that dehydration rate(AUDDC)was significantly positively correlated with kernel filling rate(KFR),hundred-grain weight(HGW),number of husk(NHK),ear width(EW),cob width(CW),kernel length(KL)and kernel moisture content at physiological maturity(KMC＿PM).The AUDDC before PM was significantly positively correlated with KFR,HGW,KMC＿PM.The AUDDC after PM was significantly positively correlated with NHK,EW,CW,KL,KMC＿PM.Combined with the germplasm evaluation of kernel dehydration characteristics,it was found that the inbred lines with excellent dehydration characteristics exhibit smaller AUDDC value,larger KDR value,lower KMC＿PM,the inbred lines with poor dehydration characteristics exhibit larger AUDDC value,smaller KDR value,higher KMC＿PM,Germplasm materials with excellent dehydration characteristics have the characteristics of early maturity,small hundred-grain weight and low proportion of keratin endosperm regions.3.Relationship between dehydration characteristics of maize inbred lines and Zm APQsFirstly,this study analyzed the expression patterns of Zm AQPs gene during kernel development in different maize inbred lines,and Zm AQPs with high expression level and genes showing that its expression is positively correlated with the kernel development process,was identified.Then,the results focused on PIP1-2,PIP1-5,TIP1-1,TIP3-1,TIP3-2,TIP3-3.Furthermore,the correlation analysis of the expression levels of related genes at the physiological maturity of kernel,their cumulative expression levels during the kernel development and the related indexes of the dehydration characteristics showed that the expression levels of PIP1-5,TIP1-1,TIP3-1 and TIP3-2 were correlated with the dehydration characteristics of kernel,and it was speculated that the Zm AQPs was involved in regulating the dehydration characteristics of maize kernel.Finally,the loss-of-function mutant tip3-1 was used as the material,and its kernel moisture content and dehydration rate were analyzed.Compared with wild-type W22,the mutant tip3-1 had higher kernel moisture content and lower dehydration rate.The results showed that Zm TIP3-1was involved in regulating the dehydration process of maize kernel development.