Genetic analysis of tropical maize inbred lines for resistance to maize lethal necrosis disease

Yoseph Beyene; Manje Gowda; L M Suresh; Stephen Mugo; Michael Olsen; Sylvester O Oikeh; Collins Juma; Amsal Tarekegne; Boddupalli M Prasanna

doi:10.1007/s10681-017-2012-3

Genetic analysis of tropical maize inbred lines for resistance to maize lethal necrosis disease

Euphytica. 2017;213(9):224. doi: 10.1007/s10681-017-2012-3. Epub 2017 Sep 2.

Authors

Yoseph Beyene¹, Manje Gowda¹, L M Suresh¹, Stephen Mugo¹, Michael Olsen¹, Sylvester O Oikeh², Collins Juma¹, Amsal Tarekegne³, Boddupalli M Prasanna¹

Affiliations

¹ International Maize and Wheat Improvement Center (CIMMYT), P.O. Box 1041-00621, Nairobi, Kenya.
² 2African Agricultural Technology Foundation (AATF), P.O. Box 30709-00100, Nairobi, Kenya.
³ International Maize and Wheat Improvement Center (CIMMYT), 12.5 km Peg Mazowe Road, Mount Pleasant, P.O. Box MP163, Harare, Zimbabwe.

Abstract

Maize lethal necrosis (MLN) disease is a recent outbreak in eastern Africa and has emerged as a significant threat to maize production in the region. The disease is caused by the co-infection of Maize chlorotic mottle virus and any member of potyviridae family. A total of 28 maize inbred lines with varying levels of tolerance to MLN were crossed in a half-diallel mating design, and the resulting 340 F₁ crosses and four commercial checks were evaluated under MLN artificial inoculation at Naivasha, Kenya in 2015 and 2016 using an alpha lattice design with two replications. The objectives of the study were to (i) investigate the magnitude of general combining ability variance (σ_GCA ²) and specific combining ability variance (σ_SCA ²) and their interaction with years; (ii) evaluate the efficiencies of GCA based prediction and hybrid performance by means of a cross-validation procedure; (iii) estimate trait correlations in the hybrids; and (iv) identify the MLN tolerant single cross hybrids to be used as female parents for three-way cross hybrids. Results of the combined analysis of variance revealed that both GCA and SCA effects were significant (P < 0.05) for all traits except for ear rot. For MLN scores at early and late stages, GCA effects were 2.5-3.5 times higher than SCA effects indicating that additive gene action is more important than non-additive gene action. The GCA based prediction efficiency for MLN resistance and grain yield accounted for 67-90% of the variations in the hybrid performance suggesting that GCA-based prediction can be proposed to predict MLN resistance and grain yield prior to field evaluation. Three parents, CKDHL120918, CML550, and CKLTI0227 with significant GCA effects for GY (0.61-1.21; P < 0.05) were the most resistant to MLN. Hybrids "CKLTI0227 × CML550", "CKDHL120918 × CKLTI0138", and "CKDHL120918 × CKLTI0136" ranked among the best performing hybrids with grain yield of 6.0-6.6 t/ha compared with mean yield of commercial check hybrids (0.6 t/ha). The MLN tolerant inbred lines and single cross hybrids identified in this study could be used to improve MLN tolerance in both public and private sector maize breeding programs in eastern Africa.

Keywords: Artificial inoculation; Combining ability; Diallel mating; MLN resistance; Maize.