Diallel analysis of leaf disease resistance in inbred Brazilian popcorn cultivars

Abstract

We estimated general and specific combining abilities and examined resistance to northern leaf blight (Exserohilum turcicum) and to gray leaf spot (Cercospora zeae-maydis) in a set of nine inbred popcorn lines. These inbreds were crossed in a complete diallel scheme without reciprocals, which produced 36 F(1) hybrids. Two experiments with a square lattice design and three replications were conducted during the 2008/2009 crop season, in Maringá, PR, Brazil. The severity of northern leaf blight and gray leaf spot was assessed under natural infestation conditions. Data were examined by individual and joint analysis of variance. Individual and joint Griffing's diallel analyses were carried out for adjusted means. General combining ability and specific combining ability were significant (P < 0.10) by the F-test for northern leaf blight and gray leaf spot infestation levels. This denotes that additive and non-additive gene effects both contributed to resistance to these diseases, but that the additive gene effects were more important. Among the inbred lines, P(8) and P(9) gave the highest resistance to northern leaf blight, and P(3) and P(4.3) gave the highest resistance to gray leaf spot. The hybrids P(7.4) x P(8) and P(4.3) x P(9) could be exploited by reciprocal recurrent selection to provide genotypes with both northern leaf blight and gray leaf spot resistance. Significant interaction between general combining ability and crop season (P < 0.10) denotes the importance of environment, even though the disease levels in the hybrids were quite consistent.

Genetic analysis of tropical rust resistance in popcorn lines

“…The most promising ones do not include the L 7.4 in its composition. Additionally, as according to previous studies, L7.4 is susceptible to NLB (VIEIRA et al, 2009). In fact, this reinforces the difficulty to aggregate multiple diseases resistance in popcorn lines, possibly as a consequence of popcorn narrow genetic base.…”

“…According to the general combining ability estimates ( ), negative and relevant values are desirable, since they indicated that such parental contributed to increase the resistance level on their offsprings (VIEIRA et al, 2009). In this sense, the line 9 (L 7.4 -UEM-M2) had outstanding for both 14 th -severity and AUDPC (Tables 3), and is the most appropriated for popcorn breeding programmes for tropical rust.…”

“…In this part of Brazilian germplasm, tropical rust resistance has exhibited a different inheritance pattern, compared to gray leaf spot (GLS, Cercospora spp.) and northern leaf blight (NLB, Exserohilum turcicum) resistance, which both additive and non additive effects had precious breeding possibilities, but the additive effect was major (VIEIRA et al, 2009). Likewise, tropical rust resistance sources are also supposed to be narrow than those for the two mentioned diseases.…”

Breeding value of selected blackcurrant (Ribes nigrum L.) genotypes for early-age fruit yield and its quality

“…The breeding value of a parental forms is determined primarily on the basis of the effects of the general (GCA) and specific (SCA) combining abilities of that parental forms _ Zurawicz et al 2006). The GCA of a parent for the trait under consideration determines its ability to pass on the average level of this trait to its progeny (Baker 1978;Vieira et al 2009), and the GCA effect is a measure of the additive effect of the parental genes on this trait (Griffing 1956a, b). The use of parental forms with significantly positive GCA effects for a given trait markedly increases the probability of obtaining hybrid progeny with the desired values of this trait (Bestfleisch et al 2014;Masny et al 2016a, b;.…”

<b>History of northern corn leaf blight disease in the seventh cycle of recurrent selection of an UENF-14 popcorn population

“…Damage to the green leaf area during grain filling can cause up to a 40% reduction in grain yield in susceptible hybrids (Ferguson & Carson, 2007;Wang et al, 2010;. The use of resistant cultivars has been the primary control measure of corn leaf diseases (Casela, Ferreira, & Pinto, 2006;Ferguson & Carson, 2007;Vieira et al, 2009;Ishfaq et al, 2014;Ayiga-Aluba, Edema, Tusiime, Asea, & Gibson, 2015), since it reduces production costs and minimizes management activities and environmental risks.…”