Overexpression of Arabidopsis ESR1 Induces Initiation of Shoot Regeneration
In the December issue of the Plant Cell (13:2609-2618), N-H Chua and his associates at the Rockefeller University, New York, report that they have identified a novel cDNA ESR1 (Enhancer of Shoot Regeneration) by screening an Arabidopsis cDNA library. Analysis of the ESR1 shows that it can induce shoot formation in Arabidopsis root explants in the absence of cytokinin. They also showed that in the presence of the optimum level of cytokinin concentration, overexpression of ESR1 not only enhances the shoot generation ability of root explants but its effects are synergistic. Furthermore, they observed that the overexpression of ESR1 does neither affect callus induction nor root formation indicating that it acts only on the shoot formation process. ESR1 encodes a putative transcription factor with an AP2/EREBP domain. Their results further reveal that cytokinin triggers the expression of ESR1 in wild-type Arabidopsis plants. They observed a transient increase of ESR1 transcript levels before shoot formation indicating that there is a close relationship between enhancement of transcript levels and the acquisition of competence for shoot regeneration. According to the authors, the presence of cytokinin in the shoot-inducing medium may account for a transient increase of ESR1 transcript levels during shoot regeneration from root explants. Based on their results, the authors suggest that the induction of shoot regeneration is regulated by ESR1, once the explant tissues in the culture medium acquire the competence for organogenesis.
On behalf of Bangladesh Association for Plant Tissue Culture (BAPTC) and its members I offer my heartiest congratulations to Professor N-H Chua for his personal and his team's outstanding discovery of ESR1. This finding would surely open us new vista to induce shoot regeneration to recalcitrant plants. ASIslam
