Department of Botany and Plant Sciences, University of California, Riverside, California 92521.
Plant Physiol. 1992 Jul;99(3):1184-92. doi: 10.1104/pp.99.3.1184.
The role of the scutellum and the aleurone in alpha-amylase production in the high-sugar sweet corn cultivars Illini X-tra Sweet (shrunken-2, sh2) and Illinois 677a (sugary, sugary enhancer; su se) was compared to that in the starchy (Su) hybrid Funks G4646 with the use of alpha-amylase enzyme assays, isoelectric focusing, electron microscopy, and laser scanning confocal microscopy. The scutellum of Illinois 677a had low levels of alpha-amylase activity compared to that of Funks G4646 through 10 days after imbibition, and the aleurone of Illini X-tra Sweet had negligible activity. On the isoelectric focusing gels, the Illinois 677a scutellum had fewer alpha-amylase isozymes at 7 days compared to the Funks G4646 scutellum. The Illini X-tra Sweet aleurone had no alpha-amylase isozymes. Funks G4646 scutellar epithelial and aleurone cells contained abundant rough endoplasmic reticulum, polysomes, and dictyosomes at 5 and 7 days, respectively. The scutellar epithelial cells of Illinois 677a contained fewer of these structures by 5 days, and the Illini X-tra Sweet aleurone contained mostly lipid bodies through 7 days. Few cytoplasmic membranes and little RNA were detected with laser scanning confocal microscopy in the Illini X-tra Sweet aleurone compared to Funks G4646 at 7 days. These data suggest that the scutellum of Illinois 677a and the aleurone of Illini X-tra Sweet have impaired abilities to produce alpha-amylase.
利用α-淀粉酶酶活性测定、等电聚焦、电子显微镜和激光扫描共聚焦显微镜，比较了高糖甜玉米品种 Illini X-tra Sweet（皱缩-2，sh2）和 Illinois 677a（含糖，糖增强剂；su se）的盾片和糊粉层在α-淀粉酶生产中的作用与淀粉质（Su）杂种 Funks G4646 的作用。与 Funks G4646 相比，Illinois 677a 的盾片在吸水后 10 天内的α-淀粉酶活性较低，而 Illini X-tra Sweet 的糊粉层几乎没有活性。在等电聚焦凝胶上，Illinois 677a 的盾片在 7 天时的α-淀粉酶同工酶数量比 Funks G4646 的盾片少。Illini X-tra Sweet 的糊粉层没有α-淀粉酶同工酶。在吸水后 5 天和 7 天，Funks G4646 的盾片上皮细胞和糊粉层细胞分别含有丰富的粗面内质网、多核糖体和高尔基氏体。Illinois 677a 的盾片上皮细胞在 5 天时含有较少的这些结构，而 Illini X-tra Sweet 的糊粉层在 7 天时主要含有脂滴。与 Funks G4646 相比，在 7 天时，Illini X-tra Sweet 的糊粉层中通过激光扫描共聚焦显微镜检测到的细胞质膜和 RNA 较少。这些数据表明，Illinois 677a 的盾片和 Illini X-tra Sweet 的糊粉层产生α-淀粉酶的能力受损。
