Rafiul Islam

Overexpression of a pepper basic pathogenesis-related protein 1 gene in tobacco plants enhances resistance to heavy metal and pathogen stresses

A pepper gene, CABPR1, which encodes basic pathogenesis-related protein 1, has been reported to be strongly induced after ethephon treatment, wounding, and tobacco mosaic virus infection. The potential role of CABPR1 in tolerance of biotic or abiotic stresses was examined in transgenic Nicotiana tabacum cv. xanthi plants. Overexpression of CABPR1 in tobacco plants enhanced tolerance not only to heavy metal stresses, but also to the oomycete pathogen Phytophthora nicotianae, and the bacterial pathogens Ralstonia solanacearum and Pseudomonas syringae pv. tabaci. RT-PCR revealed that the CABPR1 transgene increased expression of the PR-Q and glutathione S-transferase genes, but decreased expression of the PR-1a and thaumatin genes. Moreover, these transgenic lines exhibited significant decreases in total peroxidase activity and transcription level, suggesting that overexpression of CABPR1 in tobacco cells altered the balance of redox systems. Redox imbalance in transgenic lines may lead to H2O2 accumulation, triggering tolerance to biotic and abiotic stresses.

Plant regeneration from nucllar tissues of Aegle marmelos through organogenesis

A protocol for organogenesis from nucellar explants excised from fertilized ovules of immature fruits of Aegle marmelos Corr. was developed. Adventitious buds were initiated on Murashige and Skoogs (MS) medium containing various combinations of 6-benzyladenine (BA), α-naphthalene-acetic acid (NAA), 3-indoleacetic acid and gibberellic acid. Medium containing 4.4 μm BA and 2.7 μM NAA produced the maximum number of adventitious buds per explant. Shoots were elongated by transferring explants with shoot buds to medium with a low concentration of BA (0.44 μM). Rooting of in vitro-regenerated shoots was obtained in half-strength MS medium with 4.9 μM indole-3-butyric acid. This is the first report of plant regeneration from nucellar explants of A. marmelos.

Micropropagation of Morus laevigata Wall. from mature trees.

Multiple shoots were obtained from nodal explants of 10-year-old tree of Morus laevigata on Murashige and Skoogs medium supplemented with different concentrations (0.5–5.0 mg.l−1) of benzyladenine (BA). Nodal segments taken from in vitro proliferated shoots gave further multiple shoots when cultured on the same basal medium containing 2.5 mg.l−1 BA. Repeated subculture resulted in rapid shoot multiplication at the average rate of 6-fold per subculture. In vitro raised shoots rooted on MS medium containing 0.1 mg. l−1 each of 3-indolebutyric acid (ISA) and α-naphthaleneacetic acid (NAA). The regenerated plantlets were successfully established in soil under field conditions after a few days of indoor acclimatization.

In vitro organogenesis of elephant apple (Feronia limonia)

Elephant apple (Feronia limonia L.). was micropropagated on MS medium containing 4.4 μM benzyladenine and 4.6 μM kinetin using cotyledon explants taken from in vitro-grown seedlings. Adventitious buds formed on the cotyledon developed into shoots that were rooted in half-strength MS medium containing 0.57 μM indoleacetic acid and 0.49 μM indolebutyric acid. Plants were successfully established in soil.

Regeneration of plantlets from in vitro cultured cotyledons of Aegle marmelos Corr. (Rutaceae)

Abstract Cotyledons from seedlings of various ages of Aegle marmelos were cultured on Murashige and Skoog (MS) medium supplemented with different combinations of phytohormones. The optimum seedling age was 10 days for shoot induction response and benzyladenine (BA) was superior to either kinetin, isopentenyladenine or zeatin. The optimum cytokinin (BA) concentration for bud induction was 2 mg l−1. The addition of indole-3-acetic acid (IAA; 0.2 mg l−1) improved shoot regeneration efficiency. The proximal part of the cotyledon had the highest regeneration potential. Adventitious shoots were elongated on MS medium containing 0.5 mg l−1 kinetin and 0.1 mg l−1 gibberellic acid. Approximately 25% of regenerated shoots were induced to differentiate roots on half-strength MS medium with 0.5 mg l−1 indole-3-butyric acid. The rooted plantlets were successfully transplanted to soil.

Strain and cultivar specificity in the Agrobacterium-chickpea interaction

The susceptibility of four genotypes of chickpea to four wild strains of Agrobacterium tumefaciens was evaluated. Successful transformation was dependent on specific bacterial strain-plant cultivar interactions. Agropine strain A281 was the most effective for tumor induction. Tumors displayed hormone autonomous growth, were opine positive and contained DNA that was homologous to the T-DNA of the inciting strain.

Production of plantlets from Aegle marmelos nucellar callus

Techniques have been developed for the regeneration of Aegle marmelos from nucellar explants. Slow-growing calli were induced from nucellar explants excised from 90–120 d-old developing fruits. The medium consisted of Murashige and Skoog formulation containing 40 g/l sucrose, 400 mg/l casein hydrolysate, 5 mg/l 1-naphthaleneacetic acid and 1 mg/l kinetin. The basal medium with high concentration (1–5 mg/l) of N6-benzyladenine (BA) and low concentration (0.1 mg/l) of NAA was suitable for regeneration of shoots from 3-month-old calli. Addition of 1 mg/l gibberellic acid (GA3) favoured shoot growth. Callus-derived shoots produced roots and developed into plantlets when transferred to half-strength MS medium supplemented with 0.5 mg/l indole-3-butyric acid (IBA) and 0.5 mg/l NAA. Approximately 5 months were required for the full regenerative process.

High efficiency plant regeneration from petiole explants of Carica papaya L. through organogenesis

Callus cultures were obrained from petiole explants of Carica papaya on MS medium containing 0.5–10.5 μM α-naphthaleneacetic acid (NAA) in combination with 0.5–5 μM benzyladenine (BA). Hard-green calli were transferred to MS medium containing 100 mgl−1 casein hydrolysate (CH) with specific BA-NAA formulation, where they developed adventitious buds within 2 weeks of culture. Maximum number of adventitious buds were obtained in 2 μM BA and 0.1 μM NAA. Shoot regeneration occurred from these adventitious buds by the end of the 4th week. Regenerated shoots were elongated in hormone-free medium and rooted in half-strength MS fortified with 3 UM NAA and 0.5 μM gibberellic acid (GA3). The regenerants were transferred to soil after acclimatization.

Field performance and biochemical evaluation of micropropagated mulberry plants

Microclones of different mulberry genotypes were successfully transferred to the field. The same genotypes were raised through conventional methods (cuttings). A comparative study using morphological and biochemical tests of field established micropropagated and cutting derived plants of mulberry genotypes was conducted. Micropropagated mulberry plants showed significant morphogenic vigour when compared to plants raised through cuttings. Biochemical tests of leaves revealed that, there was no significant nutritional difference between micropropagated plants and those originated from cuttings.

Adventitious shoot regeneration from root tips of intact seedlings of Aegle marmelos

SummaryIntact seedlings of Aegle marmelos Corr. were tested for their ability to produce adventitious shoots by direct culture of mature seeds on Murashige and Skoog (MS) medium supplemented with different concentrations of benzyladenine (BA); 1–2 mg l–1 BA was found to be the optimum concentration. Addition of 0.1 mg l–1 indoleacetic acid (IAA) further increased shoot proliferation efficiency. Shoot buds originated from regions adjacent to the bases of cotyledons and cotyledonary axils and roots. In many cases, adventitious shoots were produced from the enlarged apical region of root. Shoots were rooted on MS medium supplemented with indolebutyric acid (IBA). Rooted plantlets were successfully established in soil.