| Stay-green is a general term applied to a variant in which senescence is delayed,compared to a standard reference genotype,and is regarded as a desirable character closely related to yield,forage character and resisitance.Previous research had shown that the stay-green maize varieties may delay the leaf senescence process,increase the leaf stay-green function period,and improve the photosynthetic efficiency,which was the evolution direction of maize varieties.Therefore,it is of great significance for the germplasm innovation and variety breeding of maize to excavate the main effect sites of stay-green trait in maize.In this paper,through multi-year experiments,combined with linkage analysis and genome-wide association analysis,the main effect sites of stay-green related traits of maize leaves were excavated and compared with ear-releted trait loci.The main conclusions are as follows:1.The phenotypic data of the recombination inbred lines in six environments were descriptively analyzed and the results showed that there was a significant difference in the visual stay green between the two parents.The female parent Xu178 had better stay-green degree than the parent K12,Xu 178 had a stay green degree between 4.3 and 5.0,and the stay green degree of K12 between 1.3 and 2.3.In addition,the visual stay green of different families in the RIL population has a large two-way separation in each environment and obeys the normal distribution,which meets the basic requirements for QTL mapping.2.The correlation analysis in this study showed that there was a significant positive correlation between VSG and GYP,and the results of linkage analysis and genome-wide association analysis also found the consistent QTL loci and SNPs of GYP and green stay green related traits in chromosomal segment such as bin2.07 and bin6.02/6.04.The results of the study reflect to a certain extent the stay green traits and grain yield have a common genetic basis,and provide theoretical support for the phenomenon that the stay green maize can increase yield,which further deepens people's understanding of the molecular basis for stay green maize.3.Combining the results of QTL mapping and genome-wide association analysis,it was found that there were a total of 6 consistent genetic loci detected,and three stay green candidate genes were further predicted.Especially,in the bin2.07/2.08 segment,the primary site of qVSG2-2 and the primary site of qGYP2-2 were detected simultaneously.The maizereference genome was searched and found the gene Zm00001d006793,which encodes cysteine-rich receptor-like protein kinases(CRKs).Further verification of this candidate gene will help promote the development of conservation genetic improvement of maize.The above research results will provide new information for further understanding of the genetic mechanism of maize functional stay-green,and also lay a solid foundation for molecular marker-assisted breeding of maize stay-green.At the same time,it also fully shows that the combination of linkage analysis and association analysis to analyze quantitative traits is a scientific and effective research method. |
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