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技术的发展，使植物淀粉组成和含量的改良以及新型淀粉的生产成为可能。玉米胚乳中淀粉质和淀粉量的性状受多对隐性基因控制，如ae、du、su 2、sh 1、sh 2、bt 1、bt 2等。AE淀粉含有较高的表观直链淀粉和凝胶渗透色谱（GPC）提取的异淀粉酶脱支材料的中间馏分，并表现出较高的糊化温度和较低的敏感性淀粉酶相比，正常玉米。性质（直链淀粉含量、支链淀粉链长分布、糊化温度、X射线衍射图谱等）含有被其它基因改变的隐性ae基因的双突变体和三突变体的淀粉的特性如下。1.凝胶化ae淀粉的GPC洗脱曲线显示出大量的直链淀粉级分，并且与ae ; su 2和ae ; sh 1淀粉的GPC洗脱曲线相似。2. ae，ae ; sh 1，ae ; du，ae ; sh 2和ae ; bt 2淀粉的直链淀粉含量在33- 37%的范围内。ae ; bt 1和ae ; sh 4淀粉的直链淀粉含量与普通玉米相近。3.与普通淀粉相比，ae，ae ; su 2和ae ; sh 1淀粉支链淀粉中DP <18的链节比例明显降低，ae ; bt 1和ae ; sh 4淀粉支链淀粉中DP <18的链节比例略有降低，ae ; sh 2和ae ; bt 2淀粉支链淀粉中DP <18的链节比例与普通淀粉相近。4.支链淀粉单元链DP 6-12峰面积比值与原淀粉糊化峰温成反比（r=-0.884）。5.由多个具有不同热特性的隐性基因控制的支链淀粉。6.粗糖化酶对ae、ae ; su 2和ae ; sh 1玉米淀粉粒的消化率均低于普通玉米。

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.