Inheritance of resistance to Colletotrichum gossypii var. cephalosporioides in cotton

Abstract

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Mixed inheritance in the genetic control of ramulosis (Colletotrichum gossypii var. cephalosporioides) resistance in cotton

“…For this same pathosystem, Oliveira et al (2010) also estimated the number of genes involved in the inheritance of the trait. The authors used quantitative genetics based on means and variance components of generations, and they noted the participation of only one major gene for the crossings Delta Opal x CNPA 2043, CNPA 999 x CNPA 2043, CNPA 999 x CNPA 2984, CNPA 2161 x BRS Facual, and CNPA 2161 x CNPA 2984.…”

“…Based on results of Oliveira et al (2010), different hypotheses of phenotypic segregation in the F 2 generation were tested, but it was assumed that only one or two genes are involved in the inheritance of the trait. For these tests, two other crossings (Delta Opal x CNPA 2984 and CNPA 999 x BRS Facual) were discarded, because, based on the previous study, the estimated number of genes involved in the inheritance of the trait were greater than two (14 and 21 genes, respectively).…”

“…Understanding the predominant gene action in the expression of a trait is crucial for directing the activities in a breeding program to obtain satisfactory genetic gains. Studies on the inheritance of this resistance have been conducted (Carvalho et al, 1988;Carvalho et al, 1994;Zandoná et al, 2006;Oliveira et al, 2010). However, there is no consensus, especially regarding the number of genes involved and if the resistance is controlled by dominant or recessive alleles.…”

“…When there is considerable environmental variation in relation to the individual effect of any gene, the effect of major genes may be mistaken for polygenic effects (Lynch and Walsh, 1998). Oliveira et al (2010), in a quantitative genetic study (emphasis in polygenes) noted that resistance to ramulosis is predominantly oligogenic (from 1 to 21 genes), and the number of genes varied among different crossings due to differentiated fixation of alleles in the parents. Nevertheless, they also concluded that about 54% of the phenotypic variation was attributed to environmental variations.…”

BRS 368RF: A glyphosate tolerant, midseason upland cotton cultivar for Northeast and North Brazilian cerrado

“…For bacterial blight, resistance was confirmed by using SNP marker ); e Amaral disease index calculated (Amaral 1969) -data from two trials artificially inoculated with Colletotrichum gossypii var. cephalosporioides, by using methods proposed by Oliveira et al (2010); f Galling index (Zhang et al 2006); g Disease index (Machado et al 2009). …”