Cloning and molecular characterization of alpha-and beta-amylase genes from cassava (Manihot esculenta Crantz)
2005
Pradit Lengbamroung(Kasetsart University. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Center for Agricultural Biotechnology) | Vichan Vichukit(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Agronomy) | Visser, Richard G.F.(Wagenigen University, 6700 AJ Wagenigen (Netherlands). Graduate School Experimental Plant Sciences. Laboratory of Plant Breeding) | Sutkhet Nakasathien(Kasetsart University. Kamphaeng Saen Campus, Nakhon Pathom (Thailand). Center for Agricultural Biotechnology)
Starch is the primary storage polysaccharide in plants and can be degraded by amylolytic enzymes. Starch-degrading enzymes can be classified into alpha-amylase (1, 4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) and beta-amylase (1, 4-alpha-D-glucan glucanohydrolase, EC 3.2.1.2). Two clones encoding alpha-amylase and beta-amylase from leaves of Thai cassava were isolated and sequenced. The partial clones were 705 and 1,960 nucleotides in length, respectively. Total RNA was extracted from several parts of the cassava plants and analyzed for the presence and level of expression of the two genes by using PCR DIG-labeled alpha-amylase and beta-amylase probes. The highest expression of the alpha-amylase gene was observed in storage roots, lower but detectable expression was in leaves and stems. On the other hand, the beta-amylase gene was observed for highly expressed in leaves and storage roots. The copy number of these genes was determined using Southern analysis indicated that alpha-amylase is a single copy gene, while beta-amylase is present in multiple copies in the cassava genome.
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