|MESEKA, S - International Institute Of Tropical Agriculture (IITA)|
|ORTEGA, A - International Institute Of Tropical Agriculture (IITA)|
|BANDYOPADHYAY, R - International Institute Of Tropical Agriculture (IITA)|
|MENKIR, A - International Institute For Tropical Agriculture|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2018
Publication Date: 9/25/2018
Citation: Meseka, S., Williams, W.P., Warburton, M.L., Brown, R.L., Ortega, A., Bandyopadhyay, R., Menkir, A. 2018. Heterotic affinity and combining ability of exotic maize inbred lines for resistance to aflatoxin accumulation. Euphytica. 214:184.
Interpretive Summary: Aflatoxin accumulation in maize (Zea mays L.) kernels is a serious economic problem that reduces grain quality and nutritional values, and causes death to livestock and humans. Maize lines that are resistant to the accumulation of aflatoxin in the grain are available, and the most resistant varieties from several institutions around the world have been identified and made available to breeders from the International Institute for Tropical Agriculture (IITA) from the USDA-ARS Corn Host Plant Resistance Research Unit (CHPRRU). IITA maize lines are highly adapted to growing conditions in Africa. CHPRRU identified lines are unrelated to the IITA lines, and how they will perform, in both aflatoxin accumulation resistance and in yield, in hybrids with IITA lines is important for breeders to know. This study provided the information for breeders to be able to predict which CHPRRU lines will make resistant and productive hybrids with IITA lines, for African farmers.
Technical Abstract: Aflatoxin accumulation in maize (Zea mays L.) kernels is a serious economic 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 hybrids in Africa. This study was designed to (i) determine the heterotic affinities of exotic aflatoxin resistant lines relative to locally adapted aflatoxin resistant lines; (ii) identify exotic inbreds with good combining ability; and (iii) determine the mode of inheritance of resistance to aflatoxin contamination in these lines. A line x tester mating design was used to determine combining ability of 12 yellow and 13 white endosperm inbred lines identified by the USDA-ARS-Corn Host Plant Resistance Unit and classify them into heterotic groups. The inbreds were crossed to two adapted testers representing two African heterotic groups, and the resulting 24 yellow and 26 white testcrosses were evaluated, along with a check hybrid, in separate trials at two locations for two years in Nigeria. General combining ability (GCA) effects were more important than specific combining ability (SCA) effects for aflatoxin and grain yield. Several exotic inbreds had negative (reducing) GCA and/or SCA effects for aflatoxin. Several also had positive GCA and/or SCA effects on yield, and a few lines showed both desired traits simultaneously. 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 production.