Diallel analysis for aflatoxin accumulation and fall armyworm leaf feeding damage in maize

Authors: Williams, William; Windham, Gary; Matthews, Gerald - Boo; Buckley, Paul

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2017
Publication Date: 12/20/2017
Citation: Williams, W.P., Windham, G.L., Matthews Jr, G.A., Buckley, P.M. 2017. Diallel analysis for aflatoxin accumulation and fall armyworm leaf feeding damage in maize. Journal of Crop Improvement. 32(2):254-263. https://doi.org/10.1080/15427528.2017.1408732.
DOI: https://doi.org/10.1080/15427528.2017.1408732

Interpretive Summary: Two of the major impediments to profitable corn production in the southern United States are losses from feeding by fall armyworm and pre-harvest contamination of the grain with aflatoxin. The fall armyworm feeds on all above-ground parts of the corn plant which can cause substantial losses in yield. The fungus, Aspergillus flavus, produces aflatoxin, a human carcinogen that is also toxic to livestock, wildlife, pets, and even humans in areas where maize is a dietary staple. High temperatures, seasonal drought, and insect damage are conducive to aflatoxin accumulation. ARS scientists at Mississippi State, Mississippi, have developed and released corn germplasm lines with resistance to either fall armyworm damage of aflatoxin accumulation, but none of the lines have resistance to both. The current investigation was undertaken to obtain information on the inheritance of resistance to fall armyworm damage and aflatoxin accumulation that could be useful in breeding hybrids for resistance to both pests. A diallel cross was produced by making all possible crosses among five germplasm lines developed as sources of resistance to fall armyworm leaf feeding damage and five lines developed as sources of resistance to aflatoxin accumulation. For resistance to both leaf feeding and to aflatoxin accumulation, general combining ability was a significant source of variation. Estimates of general combining ability effects for reduced aflatoxin accumulation were significant for Mp715 and Mp719, two of the lines selected for resistance to aflatoxin accumulation. General combining ability effects for reduced fall armyworm damage were significant for all five lines selected for fall armyworm resistance: Mp707, Mp708, Mp713, Mp714, and Mp716. Using breeding strategies that capitalize on these GCA effects should produce parental lines and hybrids with resistance to both fall armyworm and fall armyworm. Crosses between aflatoxin-resistant lines and fall armyworm-resistant lines such as Mp715 × Mp707 and Mp719 × Mp716 exhibited high levels of resistance to both pests, giving further evidence that breeding concurrently for resistance to both fall armyworm and aflatoxin accumulation should be useful in producing corn hybrids for the southern United States.

Technical Abstract: Two of the major impediments to profitable maize, Zea mays L., production in the southern United States are losses from feeding by fall armyworm, Spodoptera frugiperda (J.E. Smith), and losses from the production and accumulation of aflatoxin in maize grain. The fall armyworm feeds on all above-ground parts of the maize plant which can cause substantial direct losses in yield. The fungus, Aspergillus flavus Link:Fries , produces aflatoxin, a human carcinogen that is also toxic to livestock, wildlife, pets, and even humans in areas where maize is a dietary staple. High temperatures, seasonal drought, and insect damage are conducive to aflatoxin accumulation. A diallel cross was produced by making all possible crosses among five germplasm lines that were developed as sources of resistance to fall armyworm leaf feeding damage and five lines developed as sources of resistance to aflatoxin accumulation. For resistance to both leaf feeding and to aflatoxin accumulation, general combining ability (GCA) was a significant source of variation. Specific combining ability (SCA) was significant for fall armyworm feeding, but not aflatoxin accumulation. Estimates of GCA effects for reduced aflatoxin accumulation were significant for Mp715 and Mp719, two of the lines selected for resistance to aflatoxin accumulation. GCA effects for reduced fall armyworm damage were significant for all five lines selected for fall armyworm resistance: Mp707, Mp708, Mp713, Mp714, and Mp716. Using breeding strategies that capitalize on these GCA effects should produce parental lines and hybrids with resistance to both fall armyworm and fall armyworm. Some crosses between aflatoxin-resistant lines and fall armyworm-resistant lines such as Mp715 × Mp707 and Mp719 × Mp716 exhibited high levels of resistance to both pests, giving further evidence that breeding for resistance to both fall armyworm and aflatoxin accumulation should be worthwhile.