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Title: Variation among edible podded snap bean accessions for pod and seed sugar content

Author
item GARTNER, WES - University Of Wisconsin
item NIENHUIS, JAMES - University Of Wisconsin
item Bethke, Paul
item Kisha, Theodore

Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Research Notes
Publication Acceptance Date: 12/14/2017
Publication Date: 4/1/2018
Citation: Gartner, W., Nienhuis, J., Bethke, P.C., Kisha, T.J. 2018. Variation among edible podded snap bean accessions for pod and seed sugar content. Bean Improvement Cooperative Annual Report. 61:89-90.

Interpretive Summary:

Technical Abstract: Sugar content of immature snap bean (Phaseolus vulgaris) pods and the effects of sugars on other flavor compounds are important to consumers and affect their food and vegetable choices. The objective of this study was to identify variation within Phaseolus vulgaris in relation to sugars that affect flavor and sweetness. We developed and evaluated over two years (2014 and 2015) a diverse sub-core of 94 Plant Introductions (PI) characterized as snap beans, Romano-types, and other beans eaten as edible immature pods, as well as 20 dry bean PIs. Additional genotypes included a kidney bean (Montcalm, Andean gene pool) as well as 8 snap bean cultivars representing various market classes consumed as edible green pods. Pods were sampled when they reached sieve size 4 (a common commercial fresh market size) measured 90 degrees off the suture. Large positive Spearman rank correlations were observed between years for whole pod glucose (0.89), fructose (0.73) and sucrose (0.62) concentrations, indicating that sugar concentrations were relatively consistent over years. A large positive correlation (r=0.85**) was observed over years between the simple sugars glucose and fructose. In contrast, a large negative correlation was observed between the disaccharide sucrose with both monosaccharides, glucose (r=-0.67) and fructose (r=-0.68). Relationships between mono and disaccharides are consistent with the hypothesis that sucrose is hydrolyzed by acid invertase. Glucose and fructose are simple sugars, and represent water soluble immediate sources of energy for growth and development in pods. In contrast, sucrose is a water soluble transport sugar that may be synthesized in pods of imported from other parts of the shoot. The population of 87 edible podded and check accessions was partitioned into pod tissue and seed tissue data sets. We observed that glucose and fructose accumulated mainly in the pod tissue; in contrast, sucrose accumulated primarily in seeds.