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Resistance to Aspergillus Ear Rot and Aflatoxin Accumulation in Maize F 1 Hybrids
Author(s) -
Naidoo G.,
Forbes A. M.,
Paul C.,
White D. G.,
Rocheford T. R.
Publication year - 2002
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2002.3600
Subject(s) - biology , aflatoxin , diallel cross , hybrid , aspergillus flavus , inbred strain , inoculation , mycotoxin , conidium , horticulture , veterinary medicine , agronomy , botany , microbiology and biotechnology , genetics , gene , medicine
Unacceptable levels of contamination by aflatoxin, a carcinogenic toxin, produced by Aspergillus flavus Link:Fr can halt the sale and shipment of maize ( Zea mays L.) grain. Our objectives were to: (i) determine the relative resistance to A. flavus and aflatoxin accumulation in F 1 hybrids produced by crossing promising resistant maize inbreds, regardless of heterotic pattern; (ii) investigate the genetic basis of resistance for this subset of inbreds through diallel analysis; and (iii) determine which inbreds are the most promising sources of resistance for molecular marker mapping and breeding programs. Two historically important inbreds and six inbreds tentatively associated with reduced ear rot and inhibition of aflatoxin production were crossed in all combinations. The resulting F 1 hybrids were evaluated for two years. Ears were inoculated 20 to 24 d after midsilk by a pinboard method and a mixture of conidia of Aspergillus flavus Link:Fr. isolates. Individual ears from each plot were rated by scoring the percent visible rot in the inoculated area. Aflatoxin B 1 levels in harvested ears were determined by an indirect competitive ELISA. The highest level of resistance for ear rot and aflatoxin accumulation was detected for resistant inbred × resistant inbred F 1 hybrids, but they were not significantly different from many resistant inbred × historically important inbred F 1 hybrids. Diallel analysis indicated general combining ability (GCA) effects for ear rot and aflatoxin levels were highly significant among hybrids overall, and for the inbreds Tex6 and Oh516. The results indicate that Tex6 and Oh516 are promising resistance sources for molecular marker mapping and breeding programs in diverse genetic backgrounds.