Genetic relations between oil yield and sudden death syndrome (SDS) in soybean

Author(s)

Inocencio Junior de Oliveira

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2011-05-19

Examining board members

Natal Antonio Vello; Vanoli Fronza; José Baldin Pinheiro; Regina Helena Geribello Priolli; Mauricio Dutra Zanotto

• Advisor: Natal Antonio Vello

Abstract

The demand for vegetable oils has increased, mainly because of its use as a renewable energy source like biodiesel. Moreover, the sudden death syndrome (SDS) in soybean, caused by the fungus Fusarium solani f.sp. glycines, has become a worrying disease for soybean producers, technicians and researchers, and the adoption of an integrated control system using tolerant cultivars as an essential component has been a recommended strategy. This work aimed to verify the possibility of gathering genes for high oil yield and tolerance to SDS in the same soybean plant. The genetic system comprised a partial diallel 7x7 involving seven parents with high oil yield and seven parents tolerant to SDS. Most of the parents were experimental lines developed at the Sector of Genetics Applied to Self-Pollinated Species (ESALQ/USP). The 2008/2009 trials involved the F2 plants, and the 2009/2010 trials involved the evaluation of F2:3 progenies traits, such as agronomic characters, oil content and oil yield in the experimental field; whereas the analysis of the SDS reaction was tested in F2:4 progenies, in a greenhouse with artificial inoculation of the pathogen through a rating scale for severity of radicular symptoms. Moreover, a study of genetic association among microsatellite markers and the characters reaction to SDS and oil content in three populations was performed. The results showed the existence of variability in parents and progenies for all characters. The parent who had the highest general combining ability and average oil content was the cultivar A 7002; on the other hand, the lowest values were found in PI 520733 and IAC 100. The crosses that originated the best oil content progenies have involved the parent A 7002, except when it was crossed with IAC 100. Ten crosses (USP 70004 with USP 14-10-38, USP 14-01-20, USP 14-13-16 and M-Soy 8001; USP 14-10-38 with USP 70057 and USP 70080; M-Soy 8001 with USP 70006, USP 70080 and USP 70123; USP 14-01-20 x USP 70006) distinguished from the others by originating the majority of their progenies with the best features in all traits, in other words, showed early and semi-early maturity, medium height, upright plants, good or average agronomic value, high grain and oil yield, high oil content and tolerance to SDS. None of the crosses originated the majority of their progeny with the worst characteristics in all traits. Oil content showed low genetic correlation with plant height at maturity, lodging, agronomic value, yield and reaction to SDS. SDS showed a low genetic correlation with lodging, grain yield, oil content, oil yield. However, it was possible to obtain progenies with high grain and oil yield and tolerance to SDS. The microsatellite markers were polymorphic and, moreover, two SSR loci were associated with the character oil content and other two loci to the character SDS reaction. (AU)