The 2‐acetyl‐1‐pyrroline (2AP) is a key aroma compound in fragrant rice. The present study assessed the γ‐aminobutyric acid (GABA) and nitrogen (N) application induced regulations in the biochemical basis of rice aroma formation. Four N levels, that is, 0, 0.87, 1.75, and 2.61 g/pot, and two GABA treatments, that is, 0 mg/L (GABA0) and 250 mg/L (GABA250), were applied to three fragrant rice cultivars, that is, Yuxiangyouzhan, Yungengyou 14, and Basmati‐385. Results showed that GABA250 increased 2AP, Na, Mn, Zn, and Fe contents by 8.44%, 10.95%, 25.70%, 11.14%, and 43.30%, respectively, under N treatments across cultivars. The GABA250 further enhanced the activities of proline dehydrogenase (PDH), ornithine aminotransferase (OAT) (both at 15 days after heading (d AH), and diamine oxidase (DAO) (at maturity) by 20.36%, 11.24%, and 17.71%, respectively. Significant interaction between GABA and N for Mn, Zn, and Fe contents in grains, proline content in leaves, GABA content in leaves at 15 d AH and maturity stage (MS), Δ1‐pyrroline‐5‐carboxylic acid (P5C) contents in leaves at 15 d AH, and Δ1‐pyrroline‐5‐carboxylate synthase (P5CS), PDH, and OAT activities in leaves at MS was noted. Moreover, the 2AP contents in grains at MS showed a significant and positive correlation with the proline contents in the leaves at 15d AH. In conclusion, GABA250 enhanced the 2AP, Na, Mn, Zn, and Fe contents, as well as the enzyme activities involved in 2AP biosynthesis. Exogenous GABA and N application improved the 2AP contents and nutrient uptake in fragrant rice.

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Tocopherols are natural antioxidants that increase the stability of fat-containing foods and are well known for their health benefits. To investigate the variation in seed tocopherol composition of soybeans from different origins, 493 soybean accessions from different countries (China, USA, Japan, and Russia) belonging to 7 maturity groups (MG 0–VI) were grown in 2 locations (Beijing and Hainan Provinces of China) for 2 years (2017 and 2018). The results showed that significant differences (p < 0.001) were observed among the accessions and origins for individual and total tocopherol contents. The total tocopherol content ranged from 118.92 μg g−1 to 344.02 μg g−1. Accessions from the USA had the highest average concentration of γ- and total tocopherols (152.92 and 238.21 μg g−1, respectively), whereas a higher level of α-tocopherol (12.82 μg g−1) was observed in the Russian accessions. The maturity group of the accession significantly (p < 0.001) influenced all tocopherol components, and higher levels of α-, γ-, and total tocopherols were observed in early maturing accessions, while late-maturing accessions exhibited higher levels of δ-tocopherol. The inclination of tocopherol concentrations with various MGs provided further evidence of the significance of MG in soybean breeding for seed tocopherol components. Furthermore, the correlation between the seed tocopherol components and geographical factors revealed that α-, γ-, and total tocopherols had significant positive correlations with latitude, while δ-tocopherol showed an opposite trend. The elite accessions with high and stable tocopherol concentrations determined could be used to develop functional foods, industrial materials, and breeding lines to improve tocopherol composition in soybean seeds.

The aim of this study is to investigate the effect of nitrogen (N) in the regulation of grain yield, growth, and physiology and biochemistry of fragrant rice under lead (Pb) stress. Three fragrant rice cultivars (Daohuaxiang, Basmati, and Yungengyou14) were grown under two N application levels (CK, 0 kg N ha −1 , and HN, 200 kg N ha −1) under Pb-contaminated soil. The grain yield, growth, antioxidant attributes, and N metabolism of fragrant rice cultivars were investigated. Results showed that compared with CK, HN treatment increased grain yield in Daohuaxiang, Basmati, and Yungengyou14 by 24.09%, 26.74%, and 23.29%, respectively. Improvement in the effective panicle, grain number per panicle, and 1000-grain weight and agronomic traits under HN treatment was detected. HN treatment decreased the seed setting rate in the three fragrant rice cultivars. In addition, the peroxidase (POD), catalase (CAT), and glutamate synthetase (GOGAT) activity in HN treatment were increased for the three fragrant rice cultivars at both heading stage and maturity as compared to CK. The correlation between the grain yield and the other investigated parameters has also been accessed. Yungengyou14 produced the highest partial factor productivity of N and agronomic use efficiency of N. Those results suggested that N could improve the grain yield resulted from affecting the growth and physiological response of fragrant rice grown under Pb-contaminated soil.

IntroductionGlobal malnutrition continues to be a canker owing to poor eating habits and over-reliance on the major staple crops. Vegetable soybean (maodou) is gaining popularity globally as an affordable snack and vegetable.MethodsIn this study, we profiled the nutritional composition of 12 soybean cultivars at the vegetable (R6-R7) and mature (R8) stages. We also conducted an RNA-seq analysis during seed development, focusing on key biosynthesis enzymes for quality traits.ResultsThe results showed that 100 g of maodou contained 66.54% moisture, 13.49% protein, 7.81% fatty acids, 2.47% soluble sugar, abundant content of minerals, and micronutrients, including folate (462.27 μg FW) and carotenoids (3,935.41 μg FW). Also, the isoflavone content of maodou ranged between 129.26 and 2,359.35 μg/g FW. With regard to the recommended daily allowance, 100 g fresh weight of maodou can contribute 26.98, 115.57, and 11.60% of protein, folate, and zinc, respectively, and significant proportions of other nutrients including linoleic acid (21.16%), linolenic acid (42.96%), zinc (11.60%), and iron (18.01%). On a dry weight basis, maodou has two to six folds higher contents of folate, tocopherol, and carotenoid than the mature soybean. Furthermore, RNA-seq analysis revealed that key biosynthesis enzymes of quality traits are differentially expressed during seed development and may contribute to variations in the content of quality traits at the vegetable and mature stages. Correlation analysis of quality traits at both stages revealed that protein only correlated positively with zinc at the vegetable stage but negatively correlated with total tocopherol and total fatty acid at the mature stage. Complex associations among folates, soluble sugar, and isoflavones were also identified.DiscussionThis study provides insight into the nutritional contents of vegetable soybean and demonstrates that maodou is essential for meeting the nutritional requirements of most countries.

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