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| Author(s): |
Lilian Cristina Andrade de Araújo Teixeira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2016-03-04. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2016-01-29 |
| Advisor: | Sandra Helena Unêda Trevisoli; Ana Cristina Pinto Juhász; Luciany Favoreto |
| Abstract | |
Soybean [Glycine max (L.) Merrill] is an annual leguminous that has distinct purposes, among them, a growing amount is related to the human feed. There is a demand of cultivars aiming this destination, which are resistant to pathogens and plagues. A special plague is highlighted, the soybean nematode of cyst (Heterodera glycines) (NCS). It causes expressive loss of productivity. Facing this, using soybean topcrosses feed-like x grain-like this work aims: a. determine the tegument color, hilum color, and hilum spread character heritance in F2 populations; b. determine the NCS resistance heritage, as well the involved genes number and action mode estimative in order to contribute in the crosses design, which involve the parents studied, with a higher possibility of accumulation of genes which provide resistance to the NCS race 3; and c. Verify in a quantitative approach the adequacy population in an additive-dominant model, as well estimate the genetic parameter into the crossings. We used contrasting parents, being resistant to the race 3 (‘BRSMG 810C’) and two susceptible, however suitable to the human feed (‘BRSMG 790A’ and ‘BRSMG 800A’). Thus, the generations F1, RCr, RCs, and F2 were created. They were used to study heritage resistance through the character segregation. The nematode evaluations were done using as estimator the Female Index (IF) and they were analyzed by the chi-square test (χ2) to test the adjustment to the suggested model to the heritage. The F3 seeds from the F2 plants were characterized to elucidate the heritage to interest morphologic traits (seed coat color, hilum color and hilum aspect). For the morphological character of grain, the results observed of descendent were adjusted to the expected proportion, considering that there were four genes (R/I/W/T) controlling the expression coat and hilum color to both crossings. At crossing ‘BRSMG 810C’ x ‘BRSMG 800A’, the allele ii genetic owners hindered the expression of genes W and T at seed pigmentation. There was variation in the expression of spread hilum character, presenting monogenic heritance and full dominance to the characteristic. There are locus binding that gives outpouring of spread hilum with T_ locus (brown pubescence). The hybridization process was efficient to obtain genetic variability. Regarding to the nematologic evaluation, F2 plants presented two segregation patterns accepted: (resistant:susceptible) 1:15 (two complementary recessive genes) and 3:61 (one dominant gene and two complementary recessive genes). The heritability was confirmed using the BCr plants, which segregated at 1:7 proportion. Such proportion is expected in heritance conditioned to three genes. The 1:3 segregation hypothesis (two genes) was rejected in BCr. The lack of one of recessive gene provided moderate resistance to NCS race 3, accepting the hypothesis of moderately resistant: susceptible at 3:13 proportion (one dominant and one recessive). Thus, in these crossings, the moderate resistance to NCS race 3 is conditioned by two epistatic genes (one dominant and one recessive) and the accumulation of a third recessive gene provides full resistance to the phytonematodes evaluated in this article. The results highlight that both crossings have high genetic variability in the F2. The additive-dominant model was enough to explain the character, where the most important genetic effect was the additive. The NCS race 3 resistance had a great environmental influence. According to the obtained results, there is an evidence of gain with selection in the selective process. The heritability in the narrow sense of low magnitude indicates a probable weighting in the selection pressure. This fact prioritizes the selection conduction in a more advanced phase of breeding program, like in the progenies test, to obtain special cultivars to feed humans, and in the homozygote to resist to this phytonematode. (AU) | |
| FAPESP's process: | 12/15448-4 - Genetic studies of soybean populations with source of resistance to cyst nematode (race 3) derived from topcrosses food-type x grain-type |
| Grantee: | Lilian Cristina Andrade de Araújo Teixeira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |