| Maize lodging is one of the most key factors influencing the biomass yield,limiting the planting density and reducing the mechanical harvesting productivity ofmaize. Targeted screening and breeding lodging resistance varieties is an economicaland effective approach to improve the ability of maize lodging resistance. Theobjectives of this research are to screen the lodging resistance of germplasm resourcesand mining significant molecular markers associated with lodging resistance relatedtraits, which would be instructive and meaningful for molecular maker-assistedbreeding in maize. A total of290maize inbred lines were used in this study and weinvestigated lodging resistance related traits in2012and2013. At the same time, atotal of201SSR markers were used to assess the genetic diversity, populationstructure, and linkage disequilibrium (LD). Finally, association analysis of7phenotype traits with201genome-wide SSR markers was conducted, and the mainresults were as follows:(1) Through evaluation of stalk pushing resistance (SPR) in the field during2years, a total of32inbred lines featured with strong lodging resistance were screenedfrom the present materials, and the representatives were PH6WC, Ye8112, Wu109,and so on. Correlation analysis was performed for7phenotypic traits of290maizeinbred lines under two years. The results showed that SPR had an outstanding positivecorrelation with third internode diameter (TID), a significant correlation with fourthinternode diameter (FID), and a significant negative correlation with ear high.(2) Genetic diversity analysis of290inbred lines was carried out using201SSRmarkers distributing on10maize chromosomes uniformly, and1,556allelic variationswere detected with an average allelic variation of7.7for201loci. The gene diversityranged from0.2930to0.9218, with an average of0.6978; the average value of PICwas0.6545, ranging from0.6676to0.7230. The present population characterized by arelatively abundant genetic variation and a higher level of gene diversity was suitablefor genome-wide association with SSR markers and traits. (3) According to population structure analysis,290maize inbred lines could beclustered into5sub-groups. On the basis of known pedigree information and breedinghistory of these lines, the five sub-groups were denoted as Lancaster, Reid,Tangsipingtou (TSPT), P group and Lvdahonggu (LRC). Compared with the other4sub-groups, the Lvdahonggu (LRC) sub-group showed higher genetic diversity.(4) The results of linkage disequilibrium analysis showed that no matterpair-wise SSRs were on the same chromosome or not, a certain extent of LD wasfound. Within the whole genome,40.6%of pair-wise SSR markers had a significantLD (p<0.01), while38.1%to80.1%of pair-wise SSR markers had a significant LDon the same chromosome.(5) Detect markers significantly associated with lodging related traits. Underthe-Log10(P)>2.5levels, a total of27and13markers for lodging resistance relatedtraits were found in2012and2013, respectively. Among those,3co-located loci onchromosome4,5,6were discovered in two years, and the QTL linked with umc1462significantly associated with fourth internode length and explained5.0%(2012) and7.2%(2013) of phenotypic variance; the QTL linked with bnlg589significantlyassociated with fourth internode diameter and explained9.5%(2012) and14.3%(2013)of phenotypic variance; the QTL linked with mmc0241significantly associated with fplant height and explained13.5%(2012) and10.2%(2013) of phenotypic variance. Atotal of24SSR loci strongly associated with lodging resistance related traits weredetected based on the meaning value of the two years. |
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