Efficient micropropagation of Citrus sinensis (L.) Osbeck from cotyledonary explants suitable for the development of commercial variety

In vitro regeneration of sweet orange (Citrus sinensis (L.) Osbeck Family: Rutaceae) has been performed via direct and indirect organogenesis. For indirect organogenesis, callus was induced and proliferated from leaf explants derived from in vitro grown seedlings on Murashige and Skoog (MS) media containing 2,4-dichlorophenoxyacetic acid (2,4-D) alone or in combination with benzyl adenine (BA) and α-naphthalene acetic acid (NAA). For direct organogenesis, explants were placed on MS media containing BA alone or in combination of NAA and gibberellic acid (GA3). Well-developed microshoots were treated with different concentrations of NAA for rhizogenesis (a two-step procedure). Different responses to these treatments were recorded depending upon the procedure used. It appears that 4.53 μM 2,4-D in combination with 5.37 μM NAA induced 93.33% callus and proliferate 86.67% of callus into 6.93 shoots per explant. Exogenous addition of 4.44 μM BA in combination with 1.54 μM GA3 enhanced shoot multiplication rate significantly (17.73±1.69 shoots/explant) in comparison to control (0.00±0.00 shoots/explant). Microshoots were rooted best (75.00±14.43%) under the treatment 100μM NAA for 48 hrs. and rooted plantlets were transferred to soil, following acclimatization were taken to maturity in the polyhouse.Keywords: Malta, Himalaya, benzyl adenine (BA), callu

Influence of kinetin on in vitro rooting and survival of banj oak (Quercus leucotrichophora L.)

A study concerning the influence of cytokinins on shoot regeneration by using different stem segments derived from in vitro raised seedlings and their subsequent rooting was conducted in banj oak (Quercus leucotrichophora L.). Cytokinins play an important role in shoot regeneration and their multiplication. In the present study, cytokinins particularly kinetin (Kn) influenced in vitro rooting and subsequent survival of these in vitro raised plants in addition to shoot multiplication. It was found that the microshoots raised via kinetin treatment rooted very well (94.44%) without any basal callus formation in comparison to microshoots raised via other cytokinin treatments (that is, BA and 2-iP). In addition to this, these in vitro raised plants showed maximum survival rate (90%) during hardening process. On the basis of available literature this is a unique and significant study regarding the comparative effect of different cytokinins on in vitro propagation study of Q. leucotrichophora by using different stem segments, particularly the influence of kinetin in vitro rooting and survival of in vitro raised plants in addition to shoot multiplication. This significant study could be useful for large scale production of successfully hardened plants so that it would be helpful in conservation of this important Himalayan forest tree species.Keywords: Quercus leucotrichophora, acclimatization, cytokinins, in vitro rootin

Chemical composition, polyphenol contents and antioxidant activities of the ‘Himalayan toothache relieving tree’ (<i>Zanthoxylum armatum</i> DC.)

The present study carried out to investigate the bioactive chemical compounds, total polyphenol content and antioxidant potential of different extracts of the Zanthoxylum armatum leaves collected from the Nainital, Uttarakhand. The GC-MS analysis of Z. armtum leaves extract resulted in the isolation of sixty, twelve, twenty-three and nineteen phytochemical constituents in methanol, ethanol, chloroform and water extracts respectively. The leaves extracts were strongly characterised by Heneicosane, Tetratetracontane, Phytol, Fargesin, (+)- Seasmin and Paulowin. Methanol extract showed maximum DPPH (2,2-Di-phenyl-1-picryl-hydrazyl) Free radical scavenging activity (IC 50 15.63 ± 0.31), Ferric Reducing Antioxidant Activity (88.98 ± 3.34 AAE ± SD) and Metal Chelating Activity (IC 50 9.89 ± 0.83). The results showed that the methanolic extract exhibited the highest phenolic content for total phenol content (98.26 ± 0.8 mg of Gallic acid equivalent/g of dry weight), total flavonoid content (61.50 ± 1.62 mg of Quercetin equivalent/g of dry weight) and total tannin content (79.96 ± 0.81 mg of Tannic acid equivalent/g of dry weight).</p