Abstract:

To establish the efficient determination of pumpkin starch components, which would be of great significance for directional breeding of special pumpkin starch varieties and rational development, the experiments were carried out. According to the dual-wavelength colorimetric principle, the determination wavelength and reference wavelength of pumpkin starch components were determined by using the purified pumpkin amylose and amylopectin and the equal absorption point diagram. The 200 μL reaction system for the determination of pumpkin starch components with dual wavelengths was determined by single factor comparison test. Finally, the content of starch components in different types of pumpkin was compared. The extreme materials were screened. The results showed that the determination wavelength of pumpkin amylose was 616 nm, the reference wavelength was 472 nm, and the determination wavelength of pumpkin amylopectin was 545 nm and the reference wavelength was 725 nm. The regression equations of pumpkin amylose and amylopectin were established. The linear relationship was good (R²>0.9900) when the amylose concentration was in the range of 0.0125-1 mg/mL, and the amylopectin concentration was in the range of 0.025-2 mg/mL. The 200 μL reaction system in a 96-well plate consisted of 20 μL of sample, 90 μL of acetate buffered saline (pH 3.5), and 90 μL of 12-fold iodine diluent. The tested 23 pumpkin materials had amylose content of 0.52-26.68 mg/g fresh flesh weight, amylopectin content of 0.03-76.13 mg/g fresh flesh weight and total starch content of 0.55-101.61 mg/g fresh flesh weight. The fresh flesh weight of 10 and 15 mg/g, the fresh flesh weight of 35 and 45 mg/g, and the fresh flesh weight of 55 and 65 mg/g could preliminarily evaluate the low, medium and high contents of amylose, amylopectin and total starch in tested pumpkin, respectively. The content of starch components of the inbred lines derived from inter-specific hybrids of Cucurbita moschata Duch. × Cucurbita maximam Duch. were higher than that of the tested C. moschata and C. maximam. Finally, seven inbred lines of C. moschata × C. maximam were screened out, which would show great potential for directional breeding of special pumpkin starch varieties. The efficient detection system for starch components in pumpkin would improve the efficiency of pumpkin starch breeding.

Key words: pumpkin, amylose, amylopectin, starch content, distant hybridization