Maize landraces White Dent and Golden Queen played a very important role in the pre-hybrid era of maize production in China. However, dozens of accessions with the same names of White Dent and Golden Queen are preserved in China National Genebank （CNG）. The present study investigated the genetic diversity of these two important groups of maize landraces, as well as the relationships within and among them. Thirty-four landrace accessions with the name of White Dent and 10 with Golden Queen preserved in CNG were fingerprinted with 52 simple sequence repeats with tailed primer M13. Summary statistics including average number of alleles per locus, gene diversity/expected heterozygosity, and observed heterozygosity were carried out using PowerMarker ver. 3.25 software. The test of Hardy-Weinberg equilibrium （HWE） and linkage disequilibrium （LD） of all the 44 maize landrace accessions were also performed by PowerMarker. We observed a significant differentiation in terms of the average number of alleles between White Dent and Golden Queen （6.44 alleles per locus in White Dent, 4.48 in Golden Queen）, while both groups of maize landraces had a relatively high but similar gene diversity （0.61 of White Dent, 0.63 of Golden Queen）. The fixation index （FST） was only 0.0044, while the percentage of loci deviated from Hardy-Weinberg equilibrium within these two groups of White Dent and Golden Queen was 32.69 and 3.92%, respectively. The rather high genetic diversity and average number of alleles per locus confirmed that both groups of landraces had a rather broad germplasm base. The extremely low fixation index showed that there was little genetic variation between White Dent and Golden Queen and the molecular variation within these two groups was remarkably high, indicating no genetic drift between White Dent and Golden Queen and suggesting different improvement approaches to these two important groups of landraces. Hardy-Weinberg equilibrium test revealed that the group of White Dent was deviated from
Understanding genetic diversity and population structure of landraces is important in utilization of these germplasm in breeding programs. In the present study, a total of 143 core maize landraces from the South Maize Region （SR） of China, which can represent the general profile of the genetic diversity in the landraces germplasm of SR, were genotyped by 54 DNA microsatellite markers. Totally, 517 alleles （ranging from 4 to 22） were detected among these landraces, with an average of 9.57 alleles per locus. The total gene diversity of these core landraces was 0.61, suggesting a rather higher level of genetic diversity. Analysis of population structure based on Bayesian method obtained the samilar result as the phylogeny neighbor-joining （N J） method. The results indicated that the whole set of 143 core landraces could be clustered into two distinct groups. All landraces from Guangdong, Hainan, and 15 landraces from Jiangxi were clustered into group 1, while those from the other regions of SR formed the group 2. The results from the analysis of genetic diversity showed that both of groups possessed a similar gene diversity, but group 1 possessed relatively lower mean alleles per locus （6.63） and distinct alleles （91） than group 2 （7.94 and 110, respectively）. The relatively high richness of total alleles and distinct alleles preserved in the core landraces from SR suggested that all these germplasm could be useful resources in germplasm enhancement and maize breeding in China.
遗传多样性分析是种质资源研究的重要组成部分。由于研究群体通常都较大,简便可靠的高通量分析技术显得尤为重要。本文概述了在SSR扩增产物检测过程中的一种基于荧光测序技术的高通量低成本分析技术体系TP-M13-SSR(simple sequence repeat with tailed primer M13)的发展历程、反应原理和应用,并比较了它与普通银染、琼脂糖检测以及常规荧光检测体系在SSR扩增产物检测上的优劣,讨论了该技术在植物遗传多样性研究中的应用潜力。
