Genetic and mycotoxin studies of Fusarium nygamai, and the effect of calcium nutrition on Fusarium s...

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" Genetic and mycotoxin studies of Fusarium nygamai, and the effect of calcium nutrition on Fusarium seedling blight of maize "
J. A. Klaasen P. E. Nelson

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1113184
Doc. No	:	TLpq304208421
Main Entry	:	J. A. Klaasen
	:	P. E. Nelson
Title & Author	:	Genetic and mycotoxin studies of Fusarium nygamai, and the effect of calcium nutrition on Fusarium seedling blight of maize\ J. A. KlaasenP. E. Nelson
College	:	The Pennsylvania State University
Date	:	1995
student score	:	1995
Degree	:	Ph.D.
Page No	:	115
Abstract	:	Two Fusarium species, F. moniliforme and F. nygamai associated with maize, millet and sorghum grain and soil may be misidentified based on morphological characteristics. Isolates of F. nygamai were mated and produced fertile perithecia on carrot agar. The new mating population has a Gibberella teleomorph. Female-fertile tester strains were recovered from the random ascospore progeny and two were identified as more reliable female parents in the detection of other members of this population. Anamorph characteristics of progeny cultures indicates that the formation of microconidia in short chains and the formation of chlamydospores are suitable characteristics for species identification of F. nygamai. Fusarium isolates from millet and sorghum grain, and soil in Nigeria, Lesotho and Zimbabwe were initially identified as short- and long-chained types of F. nygamai. Some of the strains with longer chains of microconidia which did not produce chlamydospores, but swollen hyphal cells of resistant hyphae were crossed with the mating populations "A" and "F" of F. moniliforme in section Liseola. Of the long chains of microconidia and other characteristics of F. moniliforme, 64% crossed with mating population "A". Of the isolates with short chains of microconidia and chlamydospores, characteristic of F. nygamai, 65% crossed with the testers used to produce the teleomorph of F. nygamai. Fusarium nygamai strains were mated on carrot agar to study the heritability of mating type and fumonisin production in ascospore progeny. Progeny from four crosses segregated in 1:1 ratios for loci controlling mating type. A single genetic locus controls fumonisin B (FB) production as well as higher FB and FB2 production. A quantitative trait locus for FB and FB2 production was also found through correlated responses of progeny. The role of calcium in plant growth was investigated in relation to a defense response against seedling blight of maize induced by F. moniliforme. Optimal shoot length and shoot dry weight and reduced root length were obtained with 10 and 20 mM CaCl2. The results of this study demonstrate that calcium plays a role in defense against Fusarium seedling blight and that this can be mainly attributed to its role in cell membrane and cell wall stability.
Subject	:	Biological sciences
	:	Genetics
	:	Plant pathology