A simple and efficient genetic transformation system for soybean (Glycine max (L.) Merrill) targeting apical meristem of modified half-seed explant.

The present study is an attempt to establish a fast, highly reproducible transformation with a simplified regeneration system in soybean targeting the apical meristem. The modified half-seed explants from soybean cultivar (cv.) JS335 were subjected to different time intervals of sonication (0, 1, 10, 20, and 30 min) and vacuum infiltration (0, 1, 10, 20, and 30 min) in the presence of Agrobacterium tumefaciens strain EHA105 harbouring pCAMBIA1301. The explants were then co-cultivated and subjected to a modified plant regeneration process that involves only two steps (1) primary shoot regeneration, and (2) in vitro rooting of primary shoot. The rooted plantlets were hardened and maintained in the greenhouse until maturity. Sonication treatment of 10 min, followed by plant regeneration using a modified method, recorded the highest transformation efficiency of 26.3% compared to other time duration tested. Furthermore, 10 min of vacuum infiltration alone resulted in even higher transformation efficiency after regeneration, reaching 28.0%. Interestingly, coupling sonication and vacuum infiltration for 10 min respectively produced the highest transformation efficiency after regeneration of 38.0%. The putative transformants showed gus expression in mature leaves, trifoliate leaves, flowers, and pods. The presence of hpt II was also confirmed in putative transformants, with an amplicon size of 500 bp. Quantitative real-time PCR confirmed the existence of hpt II as one to two copies in the soybean genome of T0 plants. Furthermore, the segregation pattern was observed in the T1 generation soybean plants which were confirmed using PCR for hpt II. The optimized protocol when tested with other Indian soybean cultivars showed an enhanced transformation efficiency ranging from 19.3% (cv. MAUS47) to 36.5% (cv. CO1). This optimized protocol could provide a reliable platform to overcome the challenges that are associated with the genetic engineering of soybean. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03715-8.

Exogenous application of stevioside enhances root growth promotion in soybean (Glycine max (L.) Merrill).

The present study aims to investigate the impact of externally applied stevioside (a sugar-based glycoside) on soybean root growth by examining morpho-physiological characteristics, biochemical parameters, and gene expression. Soybean seedlings (10-day-old) were treated with stevioside (0, 8.0 µM, 24.5 µM, and 40.5 µM) for four times at six days' intervals by soil drenching. Treatment with 24.5 µM stevioside significantly increased root length (29.18 cm plant-1), root numbers (38.5 plant-1), root biomass (0.95 g plant-1 FW; 0.18 g plant-1 DW), shoot length (30.96 cm plant-1), and shoot biomass (2.14 g plant-1 FW; 0.36 g plant-1 DW) compared to the control. Moreover, 24.5 µM of stevioside was effective in enhancing photosynthetic pigments, leaf relative water content, and antioxidant enzymes compared to control. Conversely, plants exposed to a higher concentration of stevioside (40.5 µM), elevated total polyphenolic content, total flavonoid content, DPPH activity, total soluble sugars, reducing sugars, and proline content. Furthermore, gene expression of root growth development-related genes such as GmYUC2a, GmAUX2, GmPIN1A, GmABI5, GmPIF, GmSLR1, and GmLBD14 in stevioside-treated soybean plants were evaluated. Stevioside (8.0 µM) showed significant expression of GmPIN1A, whereas, 40.5 µM of stevioside enhanced GmABI5 expression. In contrast, most of the root growth development genes such as GmYUC2a, GmAUX2, GmPIF, GmSLR1, and GmLBD14, were highly expressed at 24.5 µM of stevioside treatment. Taken together, our results demonstrate the potential of stevioside in improving morpho-physiological traits, biochemical status, and the expression of root development genes in soybean. Hence, stevioside could be used as a supplement to enhance plant performance.

Biotechnology Advances in Bioremediation of Arsenic: A Review.

Arsenic is a highly toxic metalloid widespread in the Earth's crust, and its contamination due to different anthropogenic activities (application of agrochemicals, mining, waste management) represents an emerging environmental issue. Therefore, different sustainable and effective remediation methods and approaches are needed to prevent and protect humans and other organisms from detrimental arsenic exposure. Among numerous arsenic remediation methods, those supported by using microbes as sorbents (microbial remediation), and/or plants as green factories (phytoremediation) are considered as cost-effective and environmentally-friendly bioremediation. In addition, recent advances in genetic modifications and biotechnology have been used to develop (i) more efficient transgenic microbes and plants that can (hyper)accumulate or detoxify arsenic, and (ii) novel organo-mineral materials for more efficient arsenic remediation. In this review, the most recent insights from arsenic bio-/phytoremediation are presented, and the most relevant physiological and molecular mechanisms involved in arsenic biological routes, which can be useful starting points in the creation of more arsenic-tolerant microbes and plants, as well as their symbiotic associations are discussed.