Genotype Identification And Functional Analysis Of Related Genes In Vernalization Development Of Wheat

Vernalization is an essential developmental trait in the growth and development of wheat,which has an important effect on the planting division,introduction,breeding and yield of wheat.In order to clarify the vernalization trait of wheat cultivars in China,reveal the relationship between growth habits of wheat cultivars and vernalization genes,the representative cultivars from 10 different ecological regions in China were selected in this study.We characterized vernalization and photoperiod genotypes using molecular markers.The results showed that strong spring cultivars carried dominant Vrn1 allele in three sites or dominant spring or weak spring cultivars dominant Vrn-B1 or dominant Vrn-D1 allele,winter or semi-winter wheat recessive alleles in all three loci;the variation of seedling-heading stage under different sowing dates with different temperature and light conditions in field was investigated by staged sowing method.It showed that the spring cultivars did not need low temperature vernalization,and the seedling-heading stage was mainly affected by the temperature above zero.The higher the temperature,the faster the development.However,winter cultivars had strict requirements for low temperature.When the low temperature couldn’t meet the vernalization requirements,the development was slow,and when it met the requirements of vernalization,the development was accelerated.We found that strong winter wheat cultivars can also heading when they couldn’t meet the condition of vernalization,which was consistent with the phenomenon of short day replacing vernalization reported by previous researchers.On this basis,we identifed the genotype and vernalization characteristics of the recombinant inbred population using molecular markers and field observations.The results showed that each line of the recessive genotype was strong winter in field and the genotypes of some lines with dominant genes were inconsistent with phenotype.and they were identified as winter in the field.Vernalization treatment proved that they were not sensitive to vernalization and should be spring cultivars.Further vernalization treatment of the 4 vernalization genotype lines found that each of the three vernalization genotypes with dominant genes had a smaller coefficient of variation for vernalization treatment,that is,they were not sensitive to vernalization response;the recessive genotypes had obvious differences in the number of days of seedling-heading stage and the coefficient of variation is bigger,indicating that they were mainly regulated by vernalization and there were unknown vernalization-related genes.Detection of the vernalization gene locus of 17 lines of recessive genotype found that the mutation in the intron region of Vrn-A1 may be related to the vernalization of wheat.The above study found that vernalization requirement of wheat was quite different among the winter genotypes carrying recessive vrn1 in all three sites.Therefore,in order to explore new vernalization related genes,we screened the candidate genes TaIRI9 and TaFLK from the vernalization expression profile of Jing 841 that expressed differently during the vernalization process.In order to fully clarify the functions of the genes TaIRI9 and TaFLK,this experiment identified the gene function using plant overexpression(TaIRI9)and RNA interference technology(TaFLK).It suggested that overexpression of TaIRI9 inhibited development of wheat growth while silencing of TaFLK accelerated development of wheat,indicating that both TaIRI9 and TaFLK genes inhibited the development of wheat and therefore delayed the heading of winter wheat.Further analysis of the expression level of TaIRI9 gene in Jing 841,Xindong 18 and 10 RIL lines(vrn-A1 vrn-B1 vrn-D1 vrn-B3)showed that the stronger the cultivar winter,the higher the TaIRI9 gene expression.The two are obviously positively correlated and the expression level of TaIRI9 gene can be used as an indicator to identify the vernalization requirement in different winter wheat cultivars.Comparison and analysis of the expression levels of TaIRI9,TaFLK genes and vernalization genes VRN1,VRN2 and VRN3 in wild type and transgenic lines found that TaIRI9 and TaFLK promoted flowering inhibitor VRN2 and flowering suppressing factors VRN1 and VRN3,indicating that both TaIRI9 and TaFLK were involved in the regulation of wheat vernalization pathways,and their regulation intensity may be the main reasons for growth habits.This will provide important proof for the identification of winter and spring characteristics of wheat(especially winter characteristics).According to the basis,provide technical support for identification of the vernalization requirement of cultivars.