Comparison of non-parametric indexes to select soybean genotypes obtained by recurrent selection

In the final steps of a breeding program, it is necessary to evaluate several traits, which makes it difficult to select the superior genotypes. This study aimed to compare nonlinear indexes in the selection of superior soybean inbred lines obtained by recurrent selection. The experiment was carried out in Londrina, Paraná State, Brazil. During the 2010/11 and 2011/12 seasons, 67 soybean inbred lines and two commercial controls (BMX Potência RR and NK 7059 RR) were evaluated. The experimental design was a randomized complete block with three replicates. The evaluated traits were: days to maturity, agronomic value, lodging, first pod insertion height, and grain yield. A combined analysis of variance for seasons was performed and the sum of ranks index, ideotype distance index, and cultivars selection index were applied. All traits were significant for the genotypic source of variation and showed complex genotype × environment interactions. The selection indexes were consistent with each other. The ideotype and cultivar selection index showed higher concordance on indication of 15 superior inbred lines with a coefficient of coincidence of 80%. The inbred lines SR-03, SR-12, SR-22, SR-41, SR-49, SR-55, SR-61, and SR-62 were indicated for all indexes and are therefore considered superior to other inbred lines.

PARAMETERS OF MALE AND FEMALE RECOMBINATION INFLUENCED BY THE T-007 SECOND CHROMOSOME IN DROSOPHILA MELANOGASTER

ABSTRACT The T-007 second chromosome line of Drosophila melanogaster, previously shown to contain genetic elements responsible for male recombination induction, appears to affect several parameters of recombination in females. In T-007 heterozygous females, the distribution of recombination (but not the total frequency) is changed from that observed in control females; relative increases are observed in the more proximal regions of the second, third and X chromosomes, while relative decreases are observed more distally. These changes are paralleled by altered coefficient of coincidence values and in an increased nondisjunction frequency of second chromosomes. The distribution of recombination in females is strikingly similar to that observed in males as measured along the second and third chromosomes, and the frequency of nondisjunction of the X and Y chromosomes is increased in T-007 heterozygous males. Based upon these results and responses to the effect of structurally rearranged heterologues (the "interchromosomal effect"), it is suggested that T-007 affects the preconditions for meiotic exchange in females. It is not yet known if elements responsible for these effects are the same elements responsible for the numerous other traits associated with the T-007 second chromosome.

ON RECOMBINATION-DEFECTIVE MEIOTIC MUTANTS IN DROSOPHILA MELANOGASTER

ABSTRACT The genetic effects of four recombination-defective meiotic mutants in D. melanogaster on recombination, segregation and the relationship between the two have been examined. The results suggest the following. (1) The anomalous meiotic segregation observed in females carrying recombination-defective meiotic mutants is a normal consequence of the reduction in exchange; each recombination-defective mutant can, therefore, be defined by a single lesion in the control of recombination. (2) Of the operations used to date to characterize this lesion, the most informative is whether the decrease in recombination is uniform along the chromosome arm or nonuniform; in particular, if the formation of recombinants is visualized as a two-step process consisting of the establishment of possible exchange points (exchange preconditions) followed by exchange itself, then mutants that uniformly decrease crossing over involve defects in the second step while mutants that result in a nonuniform decrease involve defects in the establishment of exchange preconditions. (3) Of the fourteen loci identified by recombination-defective meiotic mutants, only one (with two alleles) is involved in exchange itself; the others all reduce recombination most drastically in distal regions, suggesting that the establishment of exchange preconditions involves polar processes. (4) A very general description of the polar establishment of exchange preconditions is presented; this description has the property that if a precondition meiotic mutant affects interference, the coefficient of coincidence will be increased in proportion to the decrease in recombination which is what is observed for all recombination-defective meiotic mutants studied to date.

COMPUTERIZED MEIOTIC MAPPING IN ASPERGILLUS NIDULANS

ABSTRACT A computer system for the storage and processing of microbial meiotic data has been developed. Based on the language Fortran 4, the program retrieves relevant data and determines the order, map distances, and coefficient of coincidence for any three-gene group. Meiotic data from Aspergillus nidulans were used to test the program. A total of 61 three-gene sequences were processed, and the results were found to be compatible with the published values. The advantages and disadvantages of computer analysis for genetic analysis are discussed.

LINKAGE OF GOLD, ITS RECESSIVE LETHALITY AND SEX-RELATED VARIATION IN CROSSING-OVER IN CULEX PIPIENS (DIPTERA: CULICIDAE)

Triple backcrosses in all possible phases of 9,791 Culex pipiens L. established the sequence Gold (Gd), yellow-larva (y) and ruby-eye (ru) in linkage group 2. Segregation of none of die factors departed significantly from 1:1. The median recombination values between y and ru are 23.8% in females and 17.2% in males; both agree closely with previously published estimates. The median recombination value between Gd and y is 21.6% and there is no significant difference between that in males and females.Females showed no interference, but that in males was positive and highly significant with an estimated coefficient of coincidence of 0.77 ± 0.06. Recombination was highly variable between families and there was no correlation between the two segments. It is suggested that variability is a function of individual chromosome difference rather than of any factor such as age or temperature. A series of double intercrosses with Gd and y showed that when homozygous, Gd (or a very closely linked gene) was lethal in the early larval stage.The importance of this dominant marker is enhanced by its inferred close proximity to the single dominant gene giving resistance to DDT.