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Title: Environment and Genotype Affect Sweetpotato Storage Root Periderm Resin Glycoside Content

item Harrison Jr, Howard
item Peterson, Joseph
item Snook, Maurice

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2008
Publication Date: 8/1/2008
Citation: Harrison Jr, H.F., Peterson, J.K., Snook, M.E. 2008. Environment and Genotype Affect Sweetpotato Storage Root Periderm Resin Glycoside Content. HortScience. Allelopathy Journal 22(1) : 93-100.

Interpretive Summary: The outer layer of sweetpotato roots, the periderm, forms a protective layer against attack by diseases and insects. In addition to being a physical barrier, it also contains biological chemicals that protect by inhibiting the growth of fungi, bacteria, insects, and plants in the root zone. Resin glycosides are large molecules that are made up primarily of sugars and fatty acids, and they are important constituents of the periderm of some sweetpotato varieties. Total periderm resin glycoside (PRG) content has been linked to insect resistance and the ability of some varieties to inhibit the growth of other plants. The purpose of this study was to investigate the role environmental conditions and genetics on sweetpotato PRG content. In this study, sweetpotato varieties varied in PRG content from 0.04 to 10.02% of the periderm dry weight. While the average PRG contents of 10 varieties varied between environments, the relative content of varieties remained fairly consistent. The pest resistant varieties, Regal and Excel, were higher in PRG than the other varieties in all three experiments. PRG contents of offspring from a cross between a high content variety Excel and a low content variety SC 1149-19 ranged from 0.1 to over 20% periderm dry weight. These results indicate that breeding sweetpotatoes for high PRG content is possible. PRG content may be useful as a chemical marker to identify pest resistant sweetpotatoes, because the laboratory test use to determine PRG content is quicker and more consistent than the extensive field testing currently used for resistance breeding.

Technical Abstract: Resin glycosides are complex compounds composed primarily of fatty acids and sugars that contribute to allelopathic potential and pest resistance in sweetpotato. Total periderm resin glycoside (PRG) contents of 10 sweetpotato (Ipomoea batatas L.) clones grown in three different field trials was determined using high pressure liquid chromatography. Average PRG contents of the clones ranged from 0.04 to 10.02% of periderm dry weight. Analysis of variance indicated that genotype accounted for most of the variation when the trials were analyzed separately; however; when PRG contents from the three trials were combined and analyzed using a factorial design, environment and the genotype x environment interaction variances were also highly significant. Average PRG contents of progeny from a cross between a high PRG clone (Excel) and a low PRG clone (SC 1149-19) were 4.13 and 4.21% periderm dry weight for the two maternal parents, respectively. PRG contents of individual progeny clones ranged from 0.1 to more than 20% of periderm dry weight, and the distribution of contents among progeny was fairly consistent for the two maternal parents. These observations indicate that breeding sweetpotato genotypes with high PRG is possible, and developing high PRG clones may an effective way of enhancing pest resistance in the crop.