| Italian ryegrass(Lolium multiflorous L.),an excellent cool-season forage grass,is widely cultivated in the world based on its characteristics of rapid growth,abundant stem and leaf,good palatability and quality and so on.Because of its importance for livestock husbandry,it has been widely used in China,however,most of the cultivars still rely on importing overseas to date.Thus the breeding program of Italian ryegrass would develop new cultivars with high yield and quality for domestic utilizing and promoting.The genetic map of Italian ryegrass could be used for locating important agronomic traits,further providing basis for gene mapping and cloning,so as to improve the accuracy for breeding work.In this study,a number of 165 hybrid progeny was produced based on distant hybridization of different morphological parents.Phenotypic detection was collected for this hybrid population,including plant height,leaf length,leaf width,chlorophyll content and heading date,while genotype analysis was constructed for linkage maps based on SRAP molecular markers.Genotypic data,phenotypic data and linkage maps were used for QTL analysis in clue to excellent traits detection,and providing foundation for breeding work and agricultural extension.1?In this study,SRAP molecular markers were used to construct genetic map for Italian ryegrass.A total of 87 clear and reproducible SRAP primer pairs were screened out and used on genotype analysis for 165 F1 progeny.A total of 314 loci were amplified using 87 SRAP primer pairs and each primer pair amplified 1?11 loci with an average of 3.6.184 loci were found by the genotype of<lmxll>on parental samples,of which 167 loci were used for genetic map construction of female parent,while 130 loci were the genotype of<nnxnp>and 112 of them were used for genetic map construction of male parental.The length of female parental linkage map was 762.10 cM,and the total number of markers was 167,so the average map distance was 4.74 cM and the average length of linkage groups was 108.87 cM,while the longest linkage group was LG6 with the length of 141.57 cM and the shortest was LG7 with the length of 84.16 cM.The total length of the male parental linkage map was 605.76 cM,and the total number of markers was 112 with the average distance of 5.88 cM and the linkage group length ranged from 64.04?112.51 cM with the average length of 86.54 cM,of which the longest linkage group was LG2,and the shortest linkage group was LG6.Both marker density of female and male parental genetic map have reached the threshold of QTL mapping analysis.2.The plant height,leaf length,leaf width,chlorophyll content and heading date of Italian ryegrass parents were measured in 2015 and the results showed significant differences,for examples,the mean plant height of male parent 'PI370676-1' was 25.68 cm higher than female parent 'PI266111-1'.The mean leaf length of male parent'PI370676-1' was 6.71cm longer than female parent 'PI266111-1'and the mean leaf length of 'PI370676-1' was 3.35mm longer than 'PI266111-1',while the mean chlorophyll content of 'PI266111-1' was 10.31 higher than 'PI370676-1' and the heading date of'PI370676-1' was 21d later than 'PI266111-1'.The significant variation within F1 hybrids population was found for each of the 5 traits with the patterns of normal distribution.Transgressive segregation was expressed for leaf length,leaf width and chlorophyll content.A total of 12 QTLs for plant height,leaf length,leaf width,chlorophyll content and heading date were detected on two parents,including 7 QTLs of female linkage groups and 5 QTLs of male linkage groups.Among these,3 QTLs associated with plant height,2 QTLs associated with leaf length,1 QTL associated with leaf width,2 QTLs associated with chlorophyll content,and 4 QTLs associated with heading date.While significant effective QTLs were found for plant height on female parental linkage group 1 and male parental linkage group 4.The significant QTL of leaf length were found on the linkage group 4 of male parent,and the significant QTL of chlorophyll content was found in male parental linkage group 6.The significant QTLs of heading date were found in female linkage group 4 and male parental linkage group 5.Although the accuracy of these QTLs needs to be validated further,they still provide basics and help for future breeding program of Italian ryegrass. |
PDF Full Text Request