| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Recent progress in biotechnology and genetic engineering makes it possible to modify the starch composition and contents in plants and to produce novel starch. Many recessive genes of maize have been identified that alter the quality and quantity of starch in the endosperm, ae, du, su2, sh1, sh2, bt1, bt2 genes. The ae starch contained high apparent amylose and intermediate fractions extracted by gel permeation chromatography (GPC) of isoamylase-debranched materials, and showed higher gelatinization temperature and lower susceptibility to amylase in comparison to normal maize. The properties (amylose content, amylopectin chain-length-distribution, gelatinization temperature, X-ray diffraction pattern etc.) of starches of double-and triple-mutants containing the recessive ae gene changed by the other genes as follows. 1. GPC elution profile of gelatinized ae starch exhibited a large amount of the amylose fraction and was similar to those for ae ; su2 and ae ; sh1 starches. 2. Amylose contents for ae, ae ; sh1, ae ; du, ae ; sh2 and ae ; bt2 starches were in the range of 33-37%. Amylose contents of ae ; bt1 and ae ; sh4 starches were similar to that of normal maize. 3. The ratios of unit chains with DP less than 18 in amylopectin of ae, ae ; su2 and ae ; sh1 starches were greatly reduced, those of ae ; bt1 and ae ; sh4 starches were slightly reduced in comparison with normal starch and those of ae ; sh2 and ae ; bt2 starches were nearly similar to that of normal starch. 4. The ratios of peak areas of DP 6-12 of unit chains of amylopectin were in inverse proportion to the peak temperature of gelatinization of native starch (r=-0.884). 5. The starches composed of characteristic amylopectin structure were caused by multiple recessive genes exhibiting different thermal properties. 6. The digestibility of starch granules of ae, ae ; su2 and ae ; sh1 by crude glucoamylase was lower in comparison to that of normal maize.
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