Genetics of resistance to powdery mildew (Microsphaera diffusa) in Brazilian soybean populations

Abstract

Crosses between resistant and susceptible soybean cultivars were performed and the F 2 populations were obtained to study the inheritance of soybean resistance to powdery mildew and to estimate the number and action of genes related to resistance. The reaction to powdery mildew was studied in a greenhouse and pots carrying plants with symptoms were distributed among the pots carrying the genotypes to be tested as a source of inoculum. Individual plants were scored according to the method of Yorinori (1997), with modifications, and classified as resistant or susceptible. The results showed that adult soybeans plants can present resistance to powdery mildew, which is controlled by one major gene with a dominant effect.

Validation of microsatellite markers for assisted selection of soybean genotypes resistant to powdery mildew

“…The result of the test of heterogeneity (Table 1) indicates, at a probability of 66.16%, that the results of the Chi-square (÷2) test were consistent for both populations, confirming the expected segregation, with the presence of one dominant gene associated to resistance. These results are consistent with those of Gonçalves et al (2002), Grau and Laurence (1975), Mignucci and Lim (1980) and Unêda-Trevisoli et al (2002).…”

Resistance Potential to Powdery Mildew (Microsphaera diffusa Cooke and Peck) of Several Yellow and Black Soybean (Glycine max (L.) Merr) Genotypes

“…Yield loss due to infection of M. diffusa in some countries has been reported to reach 30% when M. diffusa infects at the beginning of plant growth in some susceptible varieties [13]. Powdery mildew disease was also reported in Brazil (the second world's largest soybean exporter country) where the disease occurred throughout the planting area of soybean with yield losses up to 40% [14].…”

“…Infection of powdery mildew disease is known to be influenced by resistance of soybean varieties that even in a different variety there are possibilities of different development and progression of the disease symptoms [8,9,14]. It is reported that soybean resistance against powdery mildew is an inherited resistance that is controlled by dominant genes with different effects on the level of intensity and severity of the disease [15,16].…”

“…It is reported that soybean resistance against powdery mildew is an inherited resistance that is controlled by dominant genes with different effects on the level of intensity and severity of the disease [15,16]. Other studies have shown that symptoms of powdery mildew infection can disappear and vulnerable when the plants are young and reappear when the plants are mature [14]. Powdery mildew disease management is still depending on the use of varieties that are considered to be resistant to the disease due to consideration of inefficient and ineffective of chemical control [17].…”

Screening techniques and sources of resistance to rusts and mildews in grain legumes

“…Spores collapsed shortly after germination in lines carrying this gene (Poulter et al, 2003). Resistance to powdery mildew in soybean is also controlled by a major gene (Goncalves et al, 2002). In mungbean some genetic and molecular analyses concerning resistance to powdery mildew have been performed.…”