References
W. Hara-Department of Developmental Biology, National Institute for Basic Biology, Saigo, Myodaiji, Okazaki, 444 Japan
Amylase plays a major role in the hydrolytic breakdown of reserve starch.
Genetic studies on amylase isozymes have been reported in several starchy
cereals: barley (Takano and Takeda 1985); maize (Chao and Scandalios 1969). We
also detected amylase isozymes in germinating rice seeds by means of horizontal
polyacrylamide gel electrophoresis, and confirmed amylase isozyme polymorphism
in rice varieties (O. sativa L.).
A total of 1,297 varieties were analyzed in this study. The dehulled seeds were germinated in a dark chamber at 30 degrees C for 5 days. After removing plumules and rootlets, germinating seeds were ground in 50 mM Tris-HCl buffer (pH 7.0). The homogenates were centrifuged at 10,000Xg for 5 min. An aliquot of the supernatant was used for electrophoresis. Electrophoresis was carried out at the constant ampere of 30 mA for 1 to 1.5 hr at 4 degrees C. After electrophoresis, the gel was incubated at 37 degrees C for 30 to 40 min in a 1% starch solution, buffered to pH 5.5. The starch solution was removed and the gel was soaked in a K1-1\2\ solution. Amylase-bearing bands were decolorized on a blue-brown background.
Four kinds of bands could be distinguished and the varieties examined were classified into six types (Fig. 1 Zymograms of amylase isozyme in germinating seeds of rice varieites (O. sativa L.)). Band 1 was common to the zymograms of all varieties. Frequency of each type was as follows: 18.4% (Type 1), 28.1% (Type 2), 48.8% (Type 3), 1.4% (Type 4), 18.4% (Type 5) and 0.8% (Type 6). Thhre was a clinal geographic distribution of amylase zymograms.
Fig. 1 Zymograms of amylase isozyme in germinating seeds of rice varieties (O.
sativa L.).
References
Chao, S.E. and J.G. Scandalios, 1969. Identification and gentic control of starch-degrading enzyme endosperm. Biochem. Genet. 3: 537-547.
Takano, T. and G. Takeda 1985. Polymorphism for a-amylase in germinating seed and malt of barley varieties detected by isoelectric-focussing gel electrophoresis. Japan. J. Breed. 35: 9-16.