Morphological and microsatellite marker-based characterization and diversity analysis of novel vegetable soybean [Glycine max (L.) Merrill]

BACKGROUND

Vegetable soybean seeds are among the most popular and nutrient-dense beans in the world due to their delicious flavor, high yield, superior nutritional value, and low trypsin content. There is significant potential for this crop that Indian farmers do not fully appreciate because of the limited germplasm range. Therefore, the current study aims to identify the diverse lines of vegetable soybean and explore the diversity produced by hybridizing grain and vegetable-type soybean varieties. Indian researchers have not yet published work describing and analysing novel vegetable soybean for microsatellite markers and morphological traits.

METHODS AND RESULTS

Sixty polymorphic SSR markers and 19 morphological traits were used to evaluate the genetic diversity of 21 newly developed vegetable soybean genotypes. A total of 238 alleles, ranging from 2 to 8, were found, with a mean of 3.97 alleles per locus. The polymorphism information content varied from 0.05 to 0.85, with an average of 0.60. A variation of 0.25-0.58 with a mean of 0.43 was observed for Jaccard's dissimilarity coefficient.

CONCLUSION

The diverse genotypes identified can be helpful to understand the genetics of vegetable soybean traits and can be used in improvement programs; study also explains the utility of SSR markers for diversity analysis of vegetable soybean. Here, we identified the highly informative SSRs with PIC > 0.80 (satt199, satt165, satt167, satt191, satt183, satt202, and satt126), which apply to genetic structure analysis, mapping strategies, polymorphic marker surveys, and background selection in genomics-assisted breeding.

Development and characterization of an innovative synbiotic fermented beverage based on vegetable soybean

Soymilk was produced from vegetable soybean and fermented by probiotics (Lactobacillus acidophilus La-5, Bifidobacterium animalis Bb-12) in co-culture with Streptococcus thermophilus. The composition of the fermented beverage and oligosaccharides content were determined. The effect of fructooligosaccharides and inulin on the fermentation time and viability of probiotic microorganisms throughout 28 days of storage at 5°C were evaluated. The soymilk from vegetable soybeans was fermented in just 3.2h, when pH reached 4.8. Fermentation reduced the contents of stachyose and raffinose in soymilk. Prebiotics had no effect on acidification rate and on viability of B. animalis and S. thermophilus in the fermented beverage. The viable counts of B. animalis Bb-12 remained above 108CFUmL-1 in the fermented soymilk during 28 days of storage at 5°C while L. acidophilus La-5 was decreased by 1logCFUmL-1. The fermented soymilk from vegetable soybeans showed to be a good food matrix to deliver probiotic bacteria, as well as a soy product with a lower content of non-digestible oligosaccharides.

Nutritional composition of mungbean and soybean sprouts compared to their adult growth stage

This study determined the level of phytonutrients in mungbean and soybean sprouts compared to mature mungbean grain and vegetable soybean. The comparison included landraces and improved mungbean and soybean varieties to assess the effect of breeding on the phytonutrient content of both crops. Sprouting mungbean enhanced vitamin C content 2.7-fold compared to mature mungbean grain. Relatively old mungbean accessions were superior in protein, calcium (Ca), iron (Fe), zinc (Zn), carotenoid and vitamin C content compared to improved mungbean lines at the fully mature stage. With regard to nutritional value, the vegetable soybean stage was superior to soybean sprouts in terms of content of protein (14% increase), Zn (45%), Ca (72%), and Fe (151%). Isoflavones, reported to have beneficial effects on human health, are found at high concentrations in soybean sprouts and could easily provide the recommended anticarcinogenic dose range from 1.5 to 2.0mg/kg of body weight per day.

Reduced abscisic acid content is responsible for enhanced sucrose accumulation by potassium nutrition in vegetable soybean seeds

In order to understand the physiological mechanism of potassium (K) application in enhancing sugar content of vegetable soybean seeds, pot experiments were conducted in 2014 and 2015 with two vegetable soybean (Glycine max L. Merr.) cultivars (c.v. Zhongkemaodou 1 and c.v. 121) under normal rate of nitrogen and phosphorus application. Three potassium (K) fertilization treatments were imposed: No K application (K0), 120 kg K2SO4 ha-1 at seeding (K1), and 120 kg K2SO4 ha-1 at seedling + 1% K2SO4 foliar application at flowering (K2). Contents of indole-3-acetic acid (IAA), gibberellins (GA), cytokinins (ZR) and abscisic acid (ABA) in seeds were determined from 4 to 8 weeks after flowering. K fertilization increased the contents of IAA, GA, ZR, soluble sugar, sucrose and fresh pod yield, but reduced ABA content consistently. When the contents of soluble sugar and sucrose reached the highest level at 7 weeks after flowering for the 2 cultivars, the contents of IAA、GA、ZR all reached the lowest level in general. The content of ABA in seed was negatively correlated with the sucrose content (P < 0.01, r = -0.749**, -0.768** in 2014 and -0.535**, -0.791** in 2015 for c.v.121 and c.v. Zhongkemaodou 1 respectively). The changes in ratio of the ABA to (IAA + GA + ZR) from 4 to 8 weeks after flowering affected by K application were coincident to the changes of sucrose accumulation. The reduced ratio of ABA/(IAA + GA + ZR) affected by K nutrition particularly reduced abscisic acid content plays a critical role in enhancing sucrose content, which might be a partial mechanism involved in K nutrition to improve the quality of vegetable soybean.