Association between advanced generations and genealogy in inbred lines of snap bean by the Ward-Modified Location Model
2010
da Costa Barbé, Tatiane | do Amaral Júnior, Antonio Teixeira | Gonçalves, Leandro Simões Azeredo | Rodrigues, Rosana | Scapim, Carlos Alberto
The Ward-MLM strategy first proposed by Franco et al. (Crop Sci 38:1688-1696, 1998) is a useful method for analyzing genetic divergence for genealogical comparisons. However, this method has not yet been applied in conjunction with early generation testing (EGT) and single seed descent (SSD) procedures in autogamous plant species bred to advanced generations. In this study, we quantified the diversity of 120 recombinant snap bean lines from the F₆:₇ generation, advanced by SSD from the application of EGT in F₂, to investigate the association between the grouping of lines and genealogy using the Ward-MLM method. Four F₂ populations with high pod yields were selected from crosses among five genotypes. The segregating population was advanced to F₆:₇ by the SSD method. The traits of plant height, mean pod length, number of seeds per pod, mean number of days to flowering, mean pod fiber content and pod yield were evaluated. Based on the distribution of lines in the groups by the Ward-MLM approach, variability was verified in the four populations. Furthermore, the early selection in F₂ did not limit the variability in the expression of genotypes with better agronomic performance. Thirty lines advanced by SSD for each population studied were sufficient to obtain superior genotypes. There was a relationship between the genealogy and groupings in F₆:₇, as evidenced by Group 1, G1, which contained the greatest number of lines from the crossing that were significantly enriched for their mean pod yield and Group 3, G3, which comprised the highest number of lines with a shorter plant type. These two traits, respectively, are the first and second most important traits for group stratification.
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