In vitro flowering in Bambusa bambos (L.) Voss, an anatomical perspective.

Bamboo [Bambusa bambos (L.) Voss (Syn. Bambusa arundinacea Retz.)] is an important arborescent grass with immense socio economic implications. The plant exhibits unique biological and growth characteristics including a distinct monocarpic gregarious flowering behavior. Studies on in vitro flowering in bamboo are not uncommon. The present study focuses on effect of different growth regulators on in vitro flowering in B. bambos and analyzes the morphological and developmental changes accompanying the process. Multiple shoots were raised from B. bambos seeds on MS medium supplemented with 10 µM BAP. Anatomical sections showed intense mitotic activity in the apical meristem of the main shoot and formation of additional shoot buds along the margins. For multiplication, propagules of 7-9 shoots were transferred to maintenance medium containing 5 µM BAP. Longitudinal sections of propagules showed prolific cell divisions and formation of meristemoids, which continuously gave rise to new shoots upon subculture. In vitro induction of flowering in cultures was observed in multiple shoots after 8 weeks. Transfer of multiple shoots to MS basal medium containing 10 µM NAA resulted in rooting and proliferation of inflorescences. On medium supplemented with 10 µM 2,4-D callusing and development of shoot buds and somatic embryos was followed by development of inflorescences. The report outlines a protocol that can be used to raise and proliferate flowering cultures in B. bambos.

Expression of toxin co-regulated pilus subunit A (TCPA) of Vibrio cholerae and its immunogenic epitopes fused to cholera toxin B subunit in transgenic tomato (Solanum lycopersicum).

For protection against cholera, it is important to develop efficient vaccine capable of inducing anti-toxin as well as anti-colonizing immunity against Vibrio cholerae infections. Earlier, expression of cholera toxin B subunit (CTB) in tomato was reported by us. In the present investigation, toxin co-regulated pilus subunit A (TCPA), earlier reported to be an antigen capable of providing anti-colonization immunity, has been expressed in tomato. Further, to generate more potent combinatorial antigens, nucleotides encoding P4 or P6 epitope of TCPA were fused to cholera toxin B subunit gene (ctxB) and expressed in tomato. Presence of transgenes in the tomato genome was confirmed by PCR and expression of genes was confirmed at transcript and protein level. TCPA, chimeric CTB-P4 and CTB-P6 proteins were also expressed in E. coli. TCPA protein expressed in E. coli was purified to generate anti-TCPA antibodies in rabbit. Immunoblot and G(M1)-ELISA verified the synthesis and assembly of pentameric chimeric proteins in fruit tissue of transgenic tomato plants. The chimeric protein CTB-P4 and CTB-P6 accumulated up to 0.17 and 0.096% of total soluble protein (TSP), respectively, in tomato fruits. Whereas expression of TCPA, CTB-P4 and CTB-P6 in E. coli can be utilized for development of conventional vaccine, expression of these antigens which can provide both anti-toxin as well as anti-colonization immunity, has been demonstrated in plants, in a form which is potentially capable of inducing immune response against cholera infection.