Heterotic affinity and combining ability of exotic maize inbred lines for resistance to aflatoxin accumulation

Abstract

Aflatoxin accumulation in maize (Zea mays L.) kernels is a serious economic and health problem that reduces grain quality and nutritional values and causes death to livestock and humans. Understanding the genetic parameters and heterotic responses of exotic maize inbred lines can facilitate their use for developing aflatoxin resistant parents of hybrids in Africa. This study was designed to (1) determine the heterotic affinities of aflatoxin resistant exotic lines, (2) identify exotic inbreds with good combining ability, and (3) determine the mode of inheritance of resistance to aflatoxin contamination in these lines. A line 9 tester mating design was used to determine combining ability of 12 yellow and 13 white inbreds and classify them into heterotic groups. The inbreds were crossed to two adapted testers representing two African heterotic groups and the resulting testcrosses along with hybrid checks were evaluated in separate trials at two locations for 2 years in Nigeria. General combining ability (GCA) effects were more important than specific combining ability effects for aflatoxin and grain yield. Among 15 exotic inbred lines having negative GCA effects for aflatoxin and 13 with positive GCA effects for grain yield, six combined the two desired traits. Five white and six yellow endosperm testcrosses were found to be good specific combiners for the two desired traits. The exotic lines with negative GCA effects for aflatoxin accumulation will be used as donor parents to develop backcross populations for generating new inbred lines with much higher levels of resistance to aflatoxin accumulation.

Large-Scale Analysis of Combining Ability and Heterosis for Development of Hybrid Maize Breeding Strategies Using Diverse Germplasm Resources

“…In generally, GCA evaluation is performed at early generations or breeding stages in order to save time and money in hybrid breeding, particularly in hybrid maize breeding (Sprague, 1946). The relative contribution of GCA and SCA effects to hybrid performance depends on traits and hybrids, and in some cases, for example, aflatoxin and grain yield (GY) (Meseka et al, 2018), GCA effects are more important than SCA effects. Evaluating GCA is inevitably a cumbersome and time-consuming task, becoming one of the major constraints in hybrid breeding programs.…”

The Sorghum Grain Mold Disease Complex: Pathogens, Host Responses, and the Bioactive Metabolites at Play

“…Post-harvest genetic resistance is especially important in ensuring the prevention of aflatoxin infection throughout storage, as Aspergillus remains a top threat to storage safety. Sorghum is a staple crop in many developing countries which lack proper storage facilities capable of limiting contamination, and post-harvest genetic resistance is an important defense measure which prevents further expenses such as fumigation from occurring (Gemede and University, 2016;Meseka et al, 2018;Soni et al, 2020).…”

Functional Biology and Molecular Mechanisms of Host-Pathogen Interactions for Aflatoxin Contamination in Groundnut (Arachis hypogaea L.) and Maize (Zea mays L.)

“…The RAP involves maize PR-10, which exhibits ribonucleolytic and antifungal activities (Chen et al, 2006(Chen et al, , 2007; and the genes of encoding PR proteins are usually highly expressed in resistant genotypes (Chen et al, 2007). A United States-Africa collaborative project identified resistant maize inbred lines (Menkir et al, 2006(Menkir et al, , 2008Meseka et al, 2018). The project reported the development of 52 BC 1 S 4 lines from crosses between five African maize inbreds and five temperate aflatoxin-resistant lines followed by the identification of RAPs related to antifungal, stress-related, storage or regulatory protein categories (Chen et al, 2012).…”

“…Deploying pre-and post-harvest genetic resistance in new crop varieties together with good agricultural practices may provide a permanent solution to this problem (Ayalew et al, 2017;Meseka et al, 2018). In this context, it is imperative to explore and deploy all possible resistance mechanisms/methods to control aflatoxin accumulation in the field followed by best practices in the entire value chain.…”