Activity of axillary meristems dictates the architecture of both vegetative and reproductive parts of a plant. In Arabidopsis thaliana, a model eudicot species, the transcription factor LFY confers a floral fate to new meristems arising from the periphery of the reproductive shoot apex. Diverse orthologous LFY genes regulate vegetative-to-reproductive phase transition when expressed in Arabidopsis, a property not shared by RFL, the homolog in the agronomically important grass, rice. We have characterized RFL by knockdown of its expression and by its ectopic overexpression in transgenic rice. We find that reduction in RFL expression causes a dramatic delay in transition to flowering, with the extreme phenotype being no flowering. Conversely, RFL overexpression triggers precocious flowering. In these transgenics, the expression levels of known flowering time genes reveal RFL as a regulator of OsSOC1 (OsMADS50), an activator of flowering. Aside from facilitating a transition of the main growth axis to an inflorescence meristem, RFL expression status affects vegetative axillary meristems and therefore regulates tillering. The unique spatially and temporally regulated RFL expression during the development of vegetative axillary bud (tiller) primordia and inflorescence branch primordia is therefore required to produce tillers and panicle branches, respectively. Our data provide mechanistic insights into a unique role for RFL in determining the typical rice plant architecture by regulating distinct downstream pathways. These results offer a means to alter rice flowering time and plant architecture by manipulating RFL-mediated pathways.axillary meristem ͉ inflorescence branching ͉ flowering transition ͉ tillering A rabidopsis thaliana LFY and its homologs encode an evolutionarily conserved land plant-specific transcription factor. Early studies on the expression pattern and phenotypes of loss-of-function mutations in LFY and FLO, homologs in two dicots A. thaliana and Antirrhinum majus, showed them to confer a floral fate to new meristems arising on the flanks of the shoot apex (1, 2). LFY homologs from species as diverse as gymnosperms, primitive land plants, and from many angiosperms retain the ability to at least partially complement Arabidopsis lfy mutants (3). These data show activation of floral meristem fate to be a conserved LFY function. Protein domains recognizable in all LFY homologs are an N-terminal proline-rich domain and a C-terminal domain; substitutions in these largely conserved DNA-binding domains are suggested to contribute to its potentially divergent functions (3). In fact, mutations in some LFY homologs show additional developmental roles (e.g., compound leaf development in pea and cell division in moss) (4, 5).Unlike the simple inflorescence of Arabidopsis, grass inflorescences are striking in the multiple kinds of branch meristems made from the apical inflorescence meristem. In rice upon transition to reproductive phase, the vegetative apical meristem transforms to an inflorescence meristem. The...

Objective: Rich endowment of traditional knowledge plays a critical role in health care, food security, culture, environment and development. Traditional knowledge is also widely used by the aromatic, flavoring, food and health industries. Plant-based traditional medicine has often been used to identify and fast-track the development of modern food and drugs. Plants synthesize such wide array of secondary metabolites that includes alkaloids, glucosinolates, terpenoids and phenylpropanoids. This study is aimed to review on indigenous and exotic medicinal plants containing an astounding food flavoring metabolite; 2-hydroxy-4-methoxybenzaldehyde (HMB). Material and Method:The review focuses on the isomer of vanillin, 2-hydroxy-4-methoxybenzaldehyde, also called MBALD, HMB, or 2H4MB, a flavor compound that is generally found in the roots and rhizomes of medicinal plants. This food flavoring phenylpropenoid is one of the least investigated isomers of vanillin. HMB is known to exhibit a wide array of medicinal properties. Though the molecular role of these metabolites remains largely unknown, they are known to play a key role in plant-environment interactions/stress response/defence signaling and application in pharmaceutical and nutraceutical industries. Discussion and Conclusion:One of the key secondary metabolites is the group of phenylproponoids synthesized either through shikimic acid pathway or the malonate/acetate pathway. Phenylalanine ammonia lyase (PAL) is the enzyme involved in phenylpropanoid pathway catalysing the deamination of phenylalanine to synthesize cinnamic acid that subsequently synthesizes variety of phenylpropanoid products. Inspite of its medicinal importance, the regulatory molecular mechanism underlying the biosynthetic pathway is largely unknown.

The present work was intended to establish an efficient and reproducible direct regeneration protocol in Colocasia esculenta and to compare the levels of total phenolics and free radical scavenging activity in in vitro regenerated and wild type plants. In vitro micropropogation protocol of the C. esculenta plant was optimized using meristem as explant. The surface sterilized explants were inoculated on MS supplemented with varied concentration and combination of auxin and cytokinins. The cultures were maintained at 26ºC under a 12 hrs photoperiod. Total phenolic content and free radical scavenging assay was carried out in wild type plants and compared with in vitro micropropagated plants using DPPH method. Statistical analysis of the data was carried out using STATISTICA 13 software. An efficient in vitro micropropagation protocol was established for C. esculenta. Antioxidant activity and total phenolic content was marginally increased in tissue cultured plants compared to wild type plants of C. esculenta.

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Objective: In vitro shoot regeneration of Decalepis hamiltonii Wight and Arn. is an endangered endemic medicinal plant using biotechnological interventions and to conserve this threatened species. Methods: In the present study, various explants such as shoot tip, leaf, and nodal segments were inoculated on Murashige and Skoog media augmented with different hormonal regimes of auxin and cytokinin combinations, namely, naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), benzyl adenine (BAP), 6-(γ,γ-Dimethylallylamino)purine (2iP), and triacontanol (TRIA). Results: Direct regeneration of shoots obtained in 3.0 mg/l 2iP alone and in combination with 0.1 mg/l IAA and/or 1.0 mg/l BAP exhibited the best response with average shootlet length being 6.5±0.17–8.0±0.92 cm, respectively, and percentage response was between 68% and 75%. The callus induced regeneration was obtained from both nodal and leaf explants with maximum response (85%) observed in combination of (2.0 mg/l) 2iP, (1.0 mg/l) IAA and (2.0 mg/l) kinetin with multiple shoots showing mean shoot number of 1.83 and average shootlet length of 6.3±0.19 cm. Conclusions: The current research provides a competent in vitro propagation method for Decalepis which could be commercialized for developing identical plants with good mass multiplication rate and for better conservation of the germplasm.

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