Untitled

Abstract

The unique capability of rice (Oryza sativa L.) seedlings to grow under anoxic conditions may result in part from their ability to express alpha-amylase and maintain the supply of sugar needed for energy metabolism. Previous studies have demonstrated that under aerobic conditions the Amy1 and Amy2 subfamily genes are regulated primarily by phytohormones while the Amy3 subfamily genes are induced during sugar starvation. The expression patterns for these alpha-amylase genes were considerably different in anoxic vs. aerobic rice seedlings. The level of total alpha-amylase mRNA under anoxic conditions was decreased in aleurone layers while it increased in the embryo. Anoxic conditions greatly diminished the expression of the Amy1A gene in aleurone. Conversely, expression of many Amy3 subfamily genes was up-regulated and prolonged in embryo tissues under anoxic conditions.

Engineering α-amylase levels in wheat grain suggests a highly sophisticated level of carbohydrate regulation during development

“…The importance of α-amylase during grain development has been previously suggested in cereal (Barrero et al , 2013; Hwang et al , 1999). However, results from this project have identified the relative importance of the specific isoform TaAMY3 and suggested the presence of an apparent control over α-amylase activity in wheat during the grain-filling process.…”

“…All subfamilies in barley or rice have been demonstrated to be expressed at different grain developmental stages and in various tissues (Hwang et al , 1999). In wheat, three isoforms of α-amylase have been clearly identified, and a fourth has been suggested based on detection of expression (Barrero et al , 2013).…”

Seed Germination and Coleoptile Growth of New Rice Lines Adapted to Hypoxic Conditions

“…High α-amylase activity is also responsible for faster of starch breakdown and higher soluble sugar concentrations in germinating seeds under flooding (Ismail et al, 2009), which is presumably necessary for coleoptile growth (Guglielminetti et al, 1995;Perata et al, 1997;Hwang et al, 1999;Ismail et al, 2009;Mori et al, 2012). In fact, the sucrose and glucose contents were 1.6-and 2.0-times higher, respectively, in IR06F459 than in IR42 (Fig.…”

“…There are several reports on the relationship between seed germination and physiological processes such as α-amylase activity and starch mobilization. Starch is a major energy source for germinating seeds and α-amylases play an essential role in starch degradation under low-oxygen conditions (Guglielminetti et al, 1995;Perata et al, 1997;Hwang et al, 1999;Ismail et al, 2009). For instance, under low oxygen stress, tolerant rice genotypes germinate and grow faster, and more seedlings survive.…”

RNA-Seq Analysis of Diverse Rice Genotypes to Identify the Genes Controlling Coleoptile Growth during Submerged Germination

“…Two of these enzymes in particular are considered essential for carbohydrate catabolism in rice seedling germination, α-amylase for starch degradation and sucrose synthase for sucrose breakdown. Previous work has shown that RAmy3D expression can be induced in response to an O 2 deficit during early germination (Guglielminetti et al, 1995a,b; Perata et al, 1997; Hwang et al, 1998, 1999), and that expression between 24 and 72 h after germination is positively correlated with shoot growth (Ismail et al, 2009). Our data show that of the ten α-amylase encoding genes we analyzed, only RAmy3D ( LOC_Os08g36910 ) was up-regulated in the five tolerant genotypes and was barely detectable in IR64.…”