Oviposition preference and life-history parameters of Callosobruchus maculatus (Coleoptera: Chrysomelidae) on different soybean (Glycine max) cultivars

BACKGROUND

Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) is one of the most destructive pests of stored legume seeds in many regions of the world. Evaluation of varietal resistance of host seeds to C. maculatus infestation can be useful in preventing severe damage. We studied the susceptibility and resistance of eight conventional soybean cultivars (Caspian, Kosar, L17, Nekador, Sari, Tapour, Williams and Zane) based on the oviposition preference (choice and no-choice tests) and population growth parameters of the pest.

RESULTS

Compared with other cultivars tested, oviposition preference of C. maculatus was the lowest on Nekador. The developmental time of C. maculatus differed from 40.34 days on Nekador to 48.35 days on L17, and was negatively correlated with the seed protein content. Other performance measures of C. maculatus did not match the oviposition preference. Immature survival and female longevity were highest on Caspian. The intrinsic rate of increase (r_m ) was higher on Tapour, Nekador and Caspian than on Zane, Williams, and Kosar. A positive correlation was observed between the r_m value of the pest and moisture content of the cultivars. Cluster analysis showed that cvs Nekador, Sari, Tapour, and Caspian were relatively susceptible, and cvs Kosar, Zane, Williams and L17 were partially resistant to this pest.

CONCLUSION

Protein and moisture contents of soybean cultivars play an important role in the development and population growth of C. maculatus, and these traits could be used to develop safe and effective management strategies for this pest on stored soybean seeds. © 2022 Society of Chemical Industry.

Time course effects of fermentation on fatty acid and volatile compound profiles of Cheonggukjang using new soybean cultivars

In this study, we investigated the effects of the potential probiotic Bacillus subtilis CSY191 on the fatty acid profiles of Cheonggukjang, a fermented soybean paste, prepared using new Korean brown soybean cultivars, protein-rich cultivar (Saedanbaek), and oil-rich cultivar (Neulchan). Twelve fatty acids were identified in the sample set-myristic, palmitic, palmitoleic, stearic, oleic, vaccenic, linoleic, α-linolenic, arachidic, gondoic, behenic, and lignoceric acids-yet, no specific changes driven by fermentation were noted in the fatty acid profiles. To further explore the effects of fermentation of B. subtilis CSY191, complete profiles of volatiles were monitored. In total, 121, 136, and 127 volatile compounds were detected in the Saedanbaek, Daewon (control cultivar), and Neulchan samples, respectively. Interestingly, the content of pyrazines-compounds responsible for pungent and unpleasant Cheonggukjang flavors-was significantly higher in Neulchan compared to that in Saedanbaek. Although the fermentation period was not a strong factor affecting the observed changes in fatty acid profiles, we noted that profiles of volatiles in Cheonggukjang changed significantly over time, and different cultivars represented specific volatile profiles. Thus, further sensory evaluation might be needed to determine if such differences influence consumers' preferences. Furthermore, additional studies to elucidate the associations between B. subtilis CSY191 fermentation and other nutritional components (e.g., amino acids) and their health-promoting potential are warranted.

Comparison of soybean cultivars for enhancement of the polyamine contents in the fermented soybean natto using Bacillus subtilis (natto)

Polyamines have beneficial properties to prevent aging-associated diseases. Raw soybean has relatively high polyamine contents; and the fermented soybean natto is a good source of polyamines. However, detailed information of diversity of polyamine content in raw soybean is lacking. The objectives of this study were to evaluate differences of polyamines among raw soybeans and select the high polyamine-containing cultivar for natto production. Polyamine contents were measured chromatographically in 16 samples of soybean, which showed high variation among soybeans as follows: 93-861 nmol/g putrescine, 1055-2306 nmol/g spermidine, and 177-578 nmol/g spermine. We then confirmed the high correlations of polyamine contents between raw soybean and natto (r = 0.96, 0.95, and 0.94 for putrescine, spermidine, and spermine, respectively). Furthermore, comparison of the polyamine contents among 9 Japanese cultivars showed that 'Nakasen-nari' has the highest polyamine contents, suggesting its suitability for enhancement of polyamine contents of natto.

Differential abilities of Korean soybean varieties to biosynthesize glyceollins by biotic and abiotic elicitors

Glyceollins synthesized in soybeans that are exposed to biotic or abiotic stress have been reported to have health benefits. Considering that glyceollins are de novo synthesized from daidzein via several enzymatic steps and that isoflavone concentration widely varies among soybean varieties, the abilities of 60 soybean cultivars to synthesize glyceollins were compared under different elicitation conditions. Soybeans accumulated glyceollins differentially depending upon the cultivar when elicited with Aspergillus sojae. Contrary to our hypothesis that high isoflavone varieties may accumulate glyceollins more efficiently upon elicitation, glyceollin accumulation in response to fungal elicitation was not related with the concentration of either total isoflavones or daidzein in soybeans. Rather the glyceollin levels were significantly affected by soybean cultivar and most effectively increased by fungal infection. The data suggest that the selection of a strong fungal elicitor and a soybean cultivar with genotype that highly expresses the genes involved in glyceollin biosynthesis is essential for efficient glyceollin production.