|Johnson, A - CLEMSON UNIVERSITY|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2006
Publication Date: March 7, 2007
Citation: Anderson, W.F., Snook, M.E., Johnson, A.W. 2007. Flavonoids of Zoysiagrass (Zoysia spp) Cultivars Varying in Fall Armyworm (Spodoptera frugiperda) Resistance. J. of Ag. and Food Chemistry 55:1853-1861. Interpretive Summary: An analysis of the variation of flavonoid chemisty among 23 zoysiagrass (Zoysia spp) cultivars was compared at one sampling grown at the Pee Dee Experimental Station in South Carolina in 1998. Twelve of the cultivars were sampled five other times during the year. The resistance to the pest fall armyworm (Spodoptera frugiperda J.E. Smith) was also assessed three times during the year. Totals and 18 specific flavonoid compounds were measured with high performance liquid chromatography (HPLC) and compared among genotypes, times of sampling during the summer and with resistance to fall armyworm. From regression analysis flavonoid peak 10 was the most associated with average fall armyworm, however, other flavonoids appeared to be involved in resistance. The flavonoid profiles of cultivars were very similar to each other for samplings times 2 through 6. The clustering analyses and family tree construction grouped certain genotypes such as fall armyworm resistant Cavalier and Zeon together, as well as J-36 and Meyer. The means of all 23 cultivars from the first sampling time were used for clustering. Flavonoid evaluations appear to be useful for measuring genetic relatedness and relation to resistance to fall armyworm. Certain times of the year may be more appropriate for sampling.
Technical Abstract: Numerous cultivars of zoysiagrass (Zoysia spp) have been developed for the turf industry in the United States. These cultivars have varying degrees of biotic and abiotic stress tolerances. One pest of importance to zoysiagrass is the fall armyworm (Spodoptera frugiperda J.E. Smith). Cultivars such as Cavalier, Emerald and Zeon have been reported to have high levels of resistance to fall armyworm. However, the phenotypic cause of resistance is not known. Flavonoids have often been associated with resistance to disease and insect pests. There are thousands of different flavonoids and they have many functions in plants. Flavonoid profiles vary greatly between genoytppes and can be used for genotypic differentiation. The objectives of this study were 1) to evaluate different zoysiagrass cultivars for resistance to fall armyworm and correlate with their flavonoid profiles and 2) determine genetic and seasonal variations of flavonoids among zoysiagrass cultivars. Twelve cultivars of zoysiagrass were evaluated in a replicated study at three times during the summer of 1998 for fall armyworm resistance. Plant samples from the twelve genotypes were collected at six times during the summer for flavonoid analysis using high performance liquid chromatography (HPLC). Stepwise regression of 18 flavonoid peaks and totals on fall armyworm resistance was performed on the twelve cultivars. From regression analysis, flavonoid peak 10 was the most closely associated with average fall armyworm weight in all three procedures (FORWARD, BACKWARD, MAXR), however, other flavonoids appeared to be involved in resistance. The mean percentages and total flavonoids of cultivars harvested six times were analyzed using the CLUSTER and TREE procedures to produce a dendrogram that illustrates clustering of cultivars at different harvest times. The flavonoid profiles of cultivars were very similar to each other for samplings 2 through 6. The dendrogram supported the results of the FASTCLUS procedure in clustering certain genotypes such as fall armyworm resistant Cavalier and Zeon together, as well as J-36 and Meyer. Eleven other cultivars (for a total of 23 cultivars) were sampled during the first sampling. The means of all 23 cultivars from the first sample date were used for clustering. Flavonoid evaluations appear to be useful for measuring genetic relatedness and relation to resistance to fall armyworm. Certain times of the year may be more appropriate for sampling, however.