Jatropha curcas L. is among important tree crops in the world with a potential for biofuel production. In Ethiopia, there is a soaring investors' interest to produce Jatropha in the country for biodiesel production. However, insufficient good quality propagation material is a major production constraint. A study was undertaken to establish a protocol for in vitro mass propagation of three Ethiopian Jatropha accessions viz. Metema, Adami Tulu and Shewa Robit through direct organogenesis from nodal explant. The result revealed that the highest percentage of shoot induction (86-90%) was achieved on MS medium with BAP (1 mg/L) and IBA (0.5 mg/L) for all the three accessions. The maximum number of shoots (6) was obtained for Metema when BAP (0.5 mg/L) with Kn (0.5 mg/L) was used. Whereas, the maximum (3.2 cm) shoot length was recorded for Shewa Robit on media with 0.5 mg/L Kn. The highest rooting percentage (84.8-88%) and maximum root number (5.43) were recorded on media supplemented with 0.25 mg/L IBA. Shewa Robit and Metema had longer roots on media with 0.25 mg/L IBA. Finally, the plantlets were successfully established in greenhouse with survival rate of 86.67% for Shewa Robit followed by 73.33 and 66.67% for Metema and Adami Tulu, respectively. This study provided optimal protocol for micro-propagation of Jatropha accessions through direct organogenesis to boost its production.

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This review covers recent advances in gibberellins(GA) signaling. Hormones gibberellins (GAs) are a class of diterpenoid acids that control many aspects of plants' life, including both developmental processes and stress responses. Nowadays, we have a good understanding of how GA levels are regulated and how this information is translated into physiological responses, mainly through genetic and biochemical approaches carried out during the last two decades in rice and Arabidopsis. Here, we review the current knowledge of the GA signaling, pathway from GA metabolism to the downstream responses and pay special attention to the regulatory molecular mechanisms. GA biosynthesis starts in plastids, whereas it's last steps, and also the GA inactivation, takes place in the cytosol. Importantly, the expression of gene coding enzymes that catalyze limiting steps, for example, the soluble GA 20-oxidases, is usually regulated by environmental cues, making the GA level very sensitive to changes in the environment. The binding of the hormone to the GID1 receptor provokes the degradation of the master negative regulators in the pathway, the transcriptional regulators DELLA proteins, and GA-promoted responses proceed. The biochemical basis of the GID1-GA-DELLA regulatory module is well established, but how DELLA proteins regulate downstream events is a matter of current intensive research. In this regard, the regulation of transcription factors' activity through direct physical interaction seems to be an extended yet not unique mechanism of DELLA action. Finally, how all this wealth of information is being used with biotechnological purposes is revised.