Genetically engineered cassava expressing Arabidopsis scopolin-beta-glucosidase for delayed postharvest physiological deterioration
Dr. Ahmad Fathoni
Research Centre for Biotechnology, LIPI Indonesia
Abstract
Rapid postharvest deterioration of cassava (Manihot esculenta Crantz) root also known as postharvest physiological deterioration (PPD) is a major problem to the utilisation and development of cassava as a food and commercial commodity. De-glucosylation of scopolin regulates the homeostasis of scopoletin in the cells by the action of scopolin-beta-glucosidase (scopolin-BG). This enzyme releases scopoletin, a major component that plays a central role in cassava root deterioration, under stress conditions. However, an understanding of how this pathway contributes to root deterioration development and the specific genes for this enzyme in cassava remains undefined. We first investigated the diversity of scopolin-BG in cassava and manipulated the de-glucosylation of scopolin pathway via over-expression of a scopolin-BG gene, BGLU23, from Arabidopsis. We found that cassava scopolin-BG is encoded by multiple genes, most of which belong to glycosyl hydrolase family-1 (GH1). Identified homologous cassava scopolin-BG genes shared low amino acid sequence similarity with the reference gene, BGLU23, between 34 and 46%, and the phylogenetic tree revealed that none of them were closely related to BGLU23. Scopoletin and scopolin were detected at low levels in fresh roots of transgenic cassava, but their accumulation was significantly increased at day 2, accompanied by the up-regulation of BGLU23. Although it appears that de-glucosylation of scopolin does not play a crucial role in the accumulation of scopoletin in cassava, some BLU23-expressing transgenic cassava showed significantly delayed PPD compared to wild type control. This study has improved our understanding of biochemical pathway involved in PPD and provided alternative way to tackle this problem.
Keywords: Plant biotechnology, cassava (Manihot esculenta Crantz), genetic engineering, postharvest deterioration, scopolin
Topic: International Conference on Sustainable Agriculture