Development of an in vitro Callus Induction Protocol and Shoot Proliferation for Selected Jatropha (Jatropha curcas) Accessions

The present study was undertaken to establish a protocol for in vitro callusing of three Jatropha accessions, namely Metema, Adami Tulu and Shewa Robit from leaf explants. The medium supplemented with combination of 4.44 μM BAP and 4.52 μM 2,4-D resulted in maximum percentage of callus (100%) formed for all accessions. The maximum shoot regeneration (66.67%) from callus with 10.13 number of shoot was obtained from Shewa Robit in MS medum fortified with TDZ (2.27 μM ) and IBA (0.49 μM ). The presence of TDZ in the shoot regeneration medium has greater influence on the induction of adventitious shoot buds, whereas MS supplemented with BAP alone and combination with IBA did not induce shoot regeneration from callus culture. The results obtained in the present study would facilitate the high callus induction and regeneration responses in Jatropha for its improvement using biotechnological tools. Plant Tissue Cult. & Biotech. 30(1): 131-141, 2020 (June)

Rapid in vitro Regeneration and Clonal Propagation of the Fastest Growing Leguminous Tree Albizia falcataria (L.) Fosberg using Leaflet Explant

Young leaflets were used as the explants for in vitro regeneration of Albizia falcataria (L.) Fosberg without callus intervention. The leaf explants produced in vitro adventitious shoot buds directly on culturing with MS supplemented with BA, IBA (4.0/0.05 mg/l) and 10% coconut milk (v/v). Addition of casein hydrolysate and coconut milk increased the production of shoot buds. The buds produced shoots and roots and showed 66% survival in a field trial. This technique offers an effective way by which large number of genetically stable plants can be produced, maintained, multiplied and transported as disease free propagules or regenerants, safely and economically. Key words: Albizia falcataria, Leaf explant, Clonal propagation, Cytology D.O.I. 10.3329/ptcb.v20i1.5966 Plant Tissue Cult. & Biotech. 20(1): 63-72, 2010 (June)

ANATOMICAL STUDIES OF IN VITRO ORGANOGENESIS INDUCED IN LEAF-DERIVED EXPLANTS OF PASSIONFRUIT

With the aim of studying the organogenesis in vitro in Passiflora edulis Sims f. flavicarpa Deg., the passionfruit, leaf-derived explants were cultured on media containing NAA or BAP and incubated either in continuous darkness or in light. The histological events leading to de novo organ formation were evaluated. Darkness induces rhizogenesis in the presence of NAA, whereas direct shoot regeneration is stimulated by light and BAP. This latter condition is recommended for passionfruit micropropagation as several adventitious shoot buds were formed from meristemoids of parenchymal origin.

REGENERATION OF PLANTLETS FROM HYPOCOTYL DERIVED CALLUS OF MORUS ALBA

Plantlets were regenerated from hypocotyl callus of Morus alba cv. MR2. Calli were established from hypocotyl segments on Murashige and Skoog (MS) medium supplemented with indoleacetic acid (0.5 mg/1) and benzyladenine (BA) (0.5 mg/1). They were transferred to MS medium with different concentrations of naphthaleneacetic acid NAA and BA for four weeks. Adventitious shoot buds were observed by transferring callus onto fresh Linsmaier and Skoog (LS) medium containing NAA (0.5 mg/1) and BA (0.75 mg/1). Shoots produced in vitro were rooted on MS medium with indolebutyric acid (0.75 mg/1).

Transgenic larch expressing genes for herbicide and insect resistance

Transgenic European larch (Larixdecidua Mill.) plants expressing a Bacillusthuringiensis Berliner (B.t.) toxin gene or the glyphosate tolerance (aroA) gene have been produced using Agrobacteriumrhizogenes mediated gene transfer. This procedure relies on direct organogenesis on wounded hypocotyls following A. rhizogenes infection. Hypocotyls of seven-day-old larch seedlings were inoculated with A. rhizogenes strain 11325, harboring the oncogenic nopaline-type pRi11325 and either binary vector pCGN1133 containing 35S NPTII and 35S ssu/aroA or pWB139 containing 35S NPTII–B.t. gene. Adventitious shoot buds were induced 4 weeks after infection. Shoots were excised, elongated, and rooted on selection medium containing kanamycin. Needles from greenhouse-grown plants were confirmed to have and to express the B.t. or aroA gene through Southern, Northern, and Western blot analyses and bioassays. This is the first report of regeneration of transgenic conifer plants expressing value-added genes using Agrobacterium-mediated gene transfer.

Imazethapyr Absorption and Fate in Leafy Spurge (Euphorbia esula)

Absorption, translocation, root release, and metabolism of imazethapyr by leafy spurge were determined under growth chamber conditions.14C-imazethapyr was applied to vegetatively propagated leafy spurge plants in a 1% solution of 28% urea ammonium nitrate containing 0.25% by vol nonionic surfactant Plants were harvested 2 and 8 d after herbicide application. Imazethapyr absorption increased from 9% at 2d to 20% at 8d. Acropetal and basipetal translocation out of the treated leaf was observed, with 3.4 to 4.2% of the applied radioactivity accumulating in the root by the end of the 8-d time course. Eight days after herbicide application, radioactivity in dormant and elongated adventitious shoot buds was twofold higher than in root tissue (compared on a dry wt basis). Two days after herbicide application, 93% of the radioactivity remained as intact imazethapyr in the treated leaf, crown, root, and shoot buds. Eight days after application, crown, roots, and adventitious shoot buds had metabolized an average of 61, 36, and 47% of the imazethapyr, respectively, while only 14% was metabolized in the treated leaf. The primary metabolite cochromatographed with 5-hydroxyethyl-imazethapyr standard.