Makoto Yamamori

Production of waxy (amylose-free) wheats

The Waxy (Wx) protein has been identified as granule-bound starch synthase (GBSS; EC 24.1.21), which is involved in amylose synthesis in plants. Although common wheat (Triticum aestivum L.) has three Wx proteins, “partial waxy mutants” lacking one or two of the three proteins have been found. Using such partial waxy mutants, tetra- and hexaploid waxy mutants with endosperms that are stained red-brown by iodine were produced. Both mutants showed loss of Wx protein and amylose. This is the first demonstration of genetic modification of wheat starch.

The waxy (Wx) proteins of maize, rice and barley

Abstract Maize waxy (Wx) protein, which has been detected as a single protein with a M r 60 000 by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), was separated into four isoforms by 2D-PAGE. The isoelectric point (p I ) of these isoforms ranged from 6.0 to 6.5. Starch isolation with SDS-buffer and heat-extraction of protein from starch granules had no effect on the 2D electrophoretic patterns of Wx protein. Rice and barley Wx proteins were also analysed by the same method and separated into four and three isoforms, respectively. Rice Wx protein isoforms had a M r of 60 000 as had been reported with a p I range from 6.5 to 7.2 while barley Wx protein isoforms had a M r of 61 000 and p I in the range of 5.8 to 6.3.