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A plant regeneration protocol via somatic embryogenesis was achieved in cotyledon and leaf explants of Capsicum baccatum, when cultured on MS medium supplemented with various concentrations of 2,4-dichlorophenoxy acetic acid (2,4-D, 0.5–5.0 mg l−1) in combination with Kinetin (Kn, 0.5 mg l−1) and 3% sucrose. Various stages were observed during the development of somatic embryos, including globular, heart, and torpedo-stages. Torpedo stage embryos were separated from the explants and subcultured on medium supplemented with various concentrations of different plant growth regulators for maturation. Maximum percentage (55%) of somatic embryo germination and plantlet formation was found at 1.0 mg l−1 BA. Finally, about 68% of plantlets were successfully established under field conditions. The regenerated plants were morphologically normal, fertile and able to set viable seeds.

A reliable and stable Agrobacterium -mediated genetic transformation system for Artemisia pallens has been developed using cell suspension cultures derived from cotyledon explants. Cotyledon, attached cotyledon, and compound leaves were found to be suitable for the induction of callus among five different types of explants tested. The yellow friable callus derived from attached cotyledon was used to initiate suspension cultures in Suspension Culture Medium (SCM) which was supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) at 2.0 mg L -1 and in combination with different concentrations of Zeatin (ZEA) at 0.25 mg L -1 . Two different shock treatments, cold shock (at 4 ℃) for 20 min and heat shock (at 45 ℃) treatment for 5 min, heat shock treatment increased the transformation efficiency. The supplementation of Pluronic F-68 (0.05%) significantly enhanced the transformation efficiency of suspension cultures, whereas Silwet L-77 (0.05%) leads to more browning of the cells and reduced the transformation efficiency. The maximum GUS intensity was recorded with an optimal intensity of blue spots in the transformed cells. The highest GUS fluorometric activity measured was 879.4 ± 113.7 nmol 4MU/mg/min in transformed cell suspension cultures. The hygromycin-resistant calli showed intense blue color in GUS histochemical assay. The transgene integration into the plant genome was confirmed by polymerase chain reaction (PCR) using uidA specific primers in six hygromycin-resistant cell lines. The partial coding sequence of three candidate reference genes, i.e., ADP-ribosylation factor ( Arf ), β-actin ( Act ), and ubiquitin ( Ubi ), and carotenoid biosynthesis pathway gene, i.e., Phytoene desaturase ( Pds ) were cloned, sequenced, and submitted to NCBI for the first time. The quantitative mRNA expression of the transgene ( uidA ) and internal ApPds gene were evaluated in transgenic callus lines. The present Agrobacterium- mediated genetic transformation protocol could help in better understanding of the metabolic pathways of this medicinally important plant and its genetic improvement., Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03251-x., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© King Abdulaziz City for Science and Technology 2022.)

Tomato ( Solanum lycopersicum L.) is an important vegetable and nutritious crop plant worldwide. They are rich sources of several indispensable compounds such as lycopene, minerals, vitamins, carotenoids, essential amino acids, and bioactive polyphenols. Plant regeneration and Agrobacterium -mediated genetic transformation system from different explants in various genotypes of tomato are necessary for genetic improvement. Among diverse plant growth regulator (PGR) combinations and concentrations tested, Zeatin (ZEA) at 2.0 mg l -1 in combination with 0.1 mg l -1 indole-3-acetic acid (IAA) generated the most shoots/explant from the cotyledon of Arka Vikas (36.48 shoots/explant) and PED (24.68 shoots/explant), respectively. The hypocotyl explant produced 28.76 shoots/explant in Arka Vikas and 19.44 shoots/explant in PED. In contrast, leaf explant induced 23.54 shoots/explant in Arka Vikas and 17.64 shoots/explant in PED. The obtained multiple shoot buds from three explant types were elongated on a medium fortified with Gibberellic acid (GA 3 ) (1.0 mg l -1 ), IAA (0.5 mg l -1 ), and ZEA (0.5 mg l -1 ) in both the cultivars. The rooting was observed on a medium amended with 0.5 mg l -1 indole 3-butyric acid (IBA). The transformation efficiency was significantly improved by optimizing the pre-culture of explants, co-cultivation duration, bacterial density and infection time, and acetosyringone concentration. The presence of transgenes in the plant genome was validated using different methods like histochemical GUS assay, Polymerase Chain Reaction (PCR), and Southern blotting. The transformation efficiency was 42.8% in PED and 64.6% in Arka Vikas. A highly repeatable plant regeneration protocol was established by manipulating various plant growth regulators (PGRs) in two tomato cultivars (Arka Vikas and PED). The Agrobacterium -mediated transformation method was optimized using different explants like cotyledon, hypocotyl, and leaf of two tomato genotypes. The present study could be favourable to transferring desirable traits and precise genome editing techniques to develop superior tomato genotypes., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)