Seedling-derived split internode and leaf explants as efficient alternatives for callus induction in tropical maize

Multiple shoot induction from embryonic axes of mature seeds supports a novel regeneration platform for biolistic DNA delivery in Theobroma cacao L.

A novel embryonic axis-based regeneration system enables rapid shoot recovery, rooting, and biolistic gene delivery in cacao, substantially shortening the timeline for plant transformation.

Somatic Embryogenesis and Embryo-to-Plant Conversion in Different Grapevine Genotypes: two Different Bottlenecks for Plant Production

Somatic embryogenesis (SE) represents a central regeneration system for the implementation of new breeding technologies in grapevine ( Vitis spp.). However, its practical use remains constrained by genotype dependence, prolonged developmental timelines, and variability associated with explant type and culture conditions. This study evaluated SE and embryo-to-plant conversion across fifteen recalcitrant European genotypes and hybrids from Italy, Spain, Portugal, and Hungary using anthers and ovaries cultured on three induction media, followed by embryo germination. Ovaries generally exhibited higher responsiveness to SE than anthers, the PIV medium showed the broadest effectiveness, although the genotype was the primary determinant of the SE process. Noteworthy, differences in embryogenesis competence did also emerge among clones of Nebbiolo cultivar highlighting intra-cultivar variability effects. By extending the duration of callus culture beyond the conventional evaluation windows and using a two-media induction protocol, the embryogenesis success increased in several genotypes, suggesting that premature callus elimination may underestimate SE potential. Regeneration experiments confirmed that the embryo-to-plant transition was the second critical step of the process. For instance, Kadarka was a cultivar with low aptitude to SE and high regeneration efficiency, whereas other genotypes displayed poor embryo germination. Overall, all fifteen recalcitrant grapevine genotypes produced SE although plant regeneration was not achieved in Graciano and Fernão Pires. The results support a two-bottleneck-based model of grapevine regeneration controlled by genotype. Inefficiencies in the embryo-to-plant conversion constitute a highly limiting factor for downstream plant breeding applications, underscoring the need for genotype-specific optimization strategies able to address both embryogenic induction and regeneration efficiency.

Development of an efficient in vitro plant regeneration system using true leaf explants of processing tomato (Solanum lycopersicum L.) ‘Ligeer 87-5’

Tomato (Solanum lycopersicum L.) is one of the most economically important horticultural crops in China, and Xinjiang is the main region in China for processing tomato production. The establishment of a robust in vitro regeneration system is a fundamental prerequisite for genetic improvement and cultivar innovation in this crop. Among the factors influencing regeneration efficiency, exogenously applied plant growth regulators (PGRs) are the most important because they regulate endogenous phytohormone homeostasis and signaling pathways. In this study, true leaf explants of the processing tomato Ligeer 87-5 were used to optimize combinations of 6-benzyladenine (6-BA) and indole-3-acetic acid (IAA) and to establish an efficient in vitro regeneration system. Full strength MS medium supplemented with 2 mg/L 6-BA and 0.2 mg/L IAA was optimal for callus induction and organogenic competence, resulting in a callus induction rate of 97.00%, an embryogenic cell incidence of 63.88%, and an adventitious bud formation rate of 21.33% after 20 days; the budding rate further increased to 63.00% after 30 days. For rapid shoot induction, a medium composed of MS + 1 mg/L 6-BA + 0.2 mg/L IAA yielded the highest adventitious bud formation rate, reaching 89.00% after 10 days. Rooting was most effective on MS medium supplemented with 0.2 mg/L IAA, achieving a 100% rooting rate after 21 days, an average root length of 11.76 cm, a 76.67% acclimatization rate after 28 days, and a 100% survival rate after hardening and transplantation. Collectively, the stage-specific application of different media substantially improved true-leaf regeneration efficiency in processing tomato plants, providing a robust platform for future genetic transformation and molecular breeding.

Direct regeneration pathway for the mass propagation of commercial banana cv. Ney Poovan (AB) using immature male flower bud explants

This study developed an efficient, variety-specific in vitro regeneration protocol for the commercially important yet recalcitrant banana cultivar Ney poovan (AB). The investigation aimed to optimise a direct organogenesis system using immature male floral hands as explants and to validate the genetic fidelity and field performance of regenerated plants. Immature male flower buds proved to be a highly effective explant source, offering reduced contamination risk compared to conventional shoot-tip cultures commonly employed for large-scale production of disease-free planting material. Among the growth regulator treatments evaluated, BAP (8 mg L-1) combined with Thidiazuron (TDZ) (0.4 mg L-1) induced the earliest greening response in cv. Ney poovan, with explants exhibiting greening within 23.40 days. The TDZ (0.6 mg L-1) alone was found to be optimal for meristematic clump formation. Maximum shoot proliferation (10.80 shoots per explant) was achieved on medium supplemented with 6-Benzylaminopurine (BAP) (5 mg L-1) and indole-3-acetic acid (IAA) (1 mg L-1). Root induction was significantly enhanced by the combined application of indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA) (1 mg L-1 each), resulting in rapid rooting within 5.20 days. Field evaluation of regenerated plants demonstrated normal vegetative growth, flowering and yield performance. The regenerated plants produced bunch weights comparable to conventionally propagated suckers, recording an average bunch weight of 14.52 kg. Genetic fidelity assessment using inter simple sequence repeats (ISSR) markers revealed very low polymorphism (6.64 %), confirming the high genetic stability and true-to-type nature of the regenerants. The protocol developed in this study provides a reliable, scalable and commercially viable approach for mass propagation of banana cv. Ney poovan banana, facilitating the production of genetically uniform, high-quality planting material for sustainable banana cultivation.

In vitro Callus Induction and LC-MS-based Phytochemical Analysis of Salacia macrosperma Wight

The present study aimed to develop a standardized tissue culture protocol for callus induction in Salacia macrosperma using juvenile leaf explants. Fifteen treatments were evaluated in a completely randomized design to optimize in vitro callus induction. A comprehensive protocol for efficient callus induction was established. Plant Preservative Mixture (PPM) was identified as the most effective agent for minimizing microbial contamination. Callus induction was achieved from the midrib region of leaf explants cultured on Murashige and Skoog (MS) medium supplemented with B5 vitamins, 2,4-dichlorophenoxyacetic acid (2,4-D), and kinetin (Kn). The highest callus response (181.33 ± 4.10) was recorded in the medium containing 7 mg L⁻¹ 2,4-D and 3 mg L⁻¹ Kn, whereas the lowest response (14.33 ± 2.40) was observed at lower concentrations of the growth regulators. The study also investigated the phytochemical composition of Salacia macrosperma roots using liquid chromatography–mass spectrometry (LC–MS). LC-MS analysis revealed a total of 1,775 metabolite features, comprising 849 identified compounds and 926 unidentified features. These compounds may play important roles in the management of metabolic disorders such as diabetes and chronic inflammation, highlighting the therapeutic potential of Salacia macrosperma.

Development of an Efficient Protocol for In Vitro Callus Induction in Salvadora persica L.