Abstract
Resent research works propose that amylopectin in endosperm starches of rice is synthesized by the concerted reaction catalyzed by AGPase, soluble starch synthase (SS), branching enzyme (BE) and debranching enzyme (DBE), though amylose is synthesized by AGPase and granule-bound starch synthase (GBSS). However, there are a number of different isoforms in respective enzymes and even less is known about the contribution of respective isoforms to the starch biosynthesis. Mutants are helpful to understand the physiological role for these enzymes. We treated the fertilized egg cell of rice with a chemical mutagen, MNU, and obtained more than one thousand and seven hundred mutants modifying endosperm starch properties, including mutants altering the expression level or the activity level of AGPase, SS, BE and DBE in addition to those for GBSS. Physiological and biochemical properties of these mutants are now being investigated.
