|KLEVORN, CLAIRE - North Carolina State University
Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2014
Publication Date: N/A
Interpretive Summary: The peanut industry has the need to keep lots of high-and normal-oleic peanuts separated. Due to the fact that peanuts on the plants are maturing at different times even at harvest dates, mixed lots are found. The changes in fatty acid profile were tracked over the course of pod development for a large seeded virginia type was compared to a normal-oleic virginia type. All samples showed a wide range of maturities throughout the study. At harvest, most of the immature pods were normal-oleic regardless of the variety. Selected seeds at harvest were genotyped and it was found the some of the seeds from the high-oleic variety did not possess the genetic mutation responsible for the high-oleic trait and thus would be high-oleic regardless of maturity. This indicates that there are two factors involved in the problem of mixed lots of normal- and high-oleic peanuts.
Technical Abstract: To address increasing problems with mixing of high oleic peanut seed lots with normal oleic seed, the development of the lipid fraction of a range of immature to mature seed in two virginia type peanut cultivars was examined. that large seeded, high-oleic vA very large seeded high-oleic cultivar (Spain) and a normal-oleic cultivar (Bailey) were harvested 148 days after planting (DAP) and analyzed without curing. High-oleic seeds were determined as those which had an oleic-to-linoleic (O/L) ratio greater than 9. Individual pods from each cultivar were evaluated for pod and seed weight, pod maturity, moisture content, and fatty acid profile. Pod maturity was determined based on mesocarp color. Pods with black, brown, and orange B mesocarp colors were considered to be mature pods. At 148 DAP, 31.6% of Bailey pods were immature compared to 23.0% for Spain. Of the immature Bailey pods, 19.2% were classified as white compared to 10.9% of Spain pods. Seeds from these pods were sorted based on their size classification. Size classifications utilized were others, number 1, medium, and extra large kernel (ELK). Within each size class, a range of maturities was present for both cultivars however for Spain, mature seeds were not present until they were large enough to be classified as ELK. Fatty acid profiling of these seeds indicated that for Spain, 100% of the ELK seeds that came from white colored pods had fatty acid profiles characteristic of normal-oleic seeds. The percentage of high-oleic seeds with normal-oleic O/L ratios was seen to decrease as the seeds moved up in maturity classes. Yellow high-oleic seeds classified as ELK had only 58.3% normal-oleic seed and orange A had 21.7% normal-oleic. The prevalence of high-oleic seed with normal-oleic O/L ratios was much less for more mature seeds. Only 5.0% of orange B, 5.0% of brown and 5.1% of black high-oleic seeds had normal-oleic O/L ratios. These results indicated that maturity plays a significant role in dictating the compositional characteristics of peanuts. Although maturity was essential for the accomplishment of maximum O/L ratios within high-oleic seed, genotypic analysis of a subset of selected seeds from this study showed that if a seed was not homozygous for both mutant alleles responsible for the high-oleic genotype, then the high-oleic phenotype was not observed. A combination of strong genetic control and maturity were required to obtain high-oleic seed. This work explored the theory that large seeded, high-oleic virginia type peanut cultivars need to mature and become commercially large enough because the immature seeds are still expressing normal-oleic acid levels, thus contaminating a high-oleic seed lot.