Investigation for properties of endosperm starches of maize containing ae gene in genetic background

近年来，生物技术和基因工程的发展使改变植物淀粉的组成和含量以及生产新型淀粉成为可能。在玉米胚乳中，已经鉴定出许多改变淀粉质量和数量的隐性基因，如ae、du、su2、sh1、sh2、bt1、bt2基因。与普通玉米相比，ae淀粉含有较高的表观直链淀粉和同淀粉酶脱支材料凝胶渗透色谱（GPC）提取的中间部分，具有较高的糊化温度和较低的淀粉酶敏感性。含有隐性ae基因的双突变体和三突变体淀粉的性质（直链淀粉含量、支链淀粉链长分布、糊化温度、x射线衍射图等）受其他基因的影响变化如下：1. 凝胶化ae淀粉的GPC洗脱谱显示出大量的直链淀粉部分，与ae相似；Su2和ae；sh1淀粉。2. ae、ae的直链淀粉含量；Sh1, ae；Du, ae；Sh2和ae；Bt2淀粉含量在33-37%之间。ae中直链淀粉含量；Bt1和ae；Sh4淀粉与普通玉米相似。3. 支链淀粉中DP小于18的单位链比例；Su2和ae；Sh1淀粉含量显著降低；Bt1和ae；与普通淀粉和ae相比，Sh4淀粉含量略有减少；Sh2和ae；Bt2淀粉与普通淀粉几乎相似。4. 支链淀粉单位链DP 6-12峰面积之比与天然淀粉糊化峰温度成反比（r=-0.884）。5. 由支链淀粉结构组成的淀粉是由多个具有不同热特性的隐性基因组成的。6. ae、ae淀粉颗粒消化率；Su2和ae；粗糖淀粉酶对Sh1的影响低于正常玉米。

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.