.ALPHA.-Amylase Affects Starch Accumulation in Rice Grains

Asatsuma, Satoru; Sawada, Chihoko; Kitajima, Aya; Asakura, Tsuyoshi; Mitsui, Toshiaki

doi:10.5458/jag.53.187

Cited by 39 publications

(30 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, a rice a-amylase isoform, aAmy3, occurred in the chloroplasts of transgenic tobacco leaves (Chen et al, 2004). Transgenic rice plants that overexpressed a-amylases produced white immature seeds with reduced starch accumulation (Asatsuma et al, 2006). This study provides further evidence that the AmyI-1 glycoprotein is localized in the amyloplasts and degrades starch granules within the organelles in rice callus cells (Figure 2).…”

Section: Amyi-1 Degrades Starch Granules In Living Rice Cellssupporting

confidence: 49%

“…Our previous studies using transgenic rice plants with suppressed expression or overexpression of AmyI-1 revealed that the enzyme glycoprotein is involved in degradation of plastidial starch in living cells (Asatsuma et al, 2005(Asatsuma et al, , 2006. Immunocytochemical analysis with specific anti-AmyI-1 antibodies, the expression and targeting of AmyI-1-GFP in redifferentiated green cells, and cell biochemical analysis of chloroplastic AmyI-1 demonstrated that AmyI-1 is present in the chloroplasts of rice leaves.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, the enzyme glycoprotein was shown to be transported and localized to the chloroplasts from the secretory pathway via Brefeldin A-sensitive vesicular transport (Nanjo et al, 2006). These results indicate that ER-to-Golgi traffic is essential for chloroplast targeting of glycoproteins in both monocot and dicot plants.Our previous studies using transgenic rice plants with suppressed expression or overexpression of AmyI-1 revealed that the enzyme glycoprotein is involved in degradation of plastidial starch in living cells (Asatsuma et al, 2005(Asatsuma et al, , 2006. Immunocytochemical analysis with specific anti-AmyI-1 antibodies, the expression and targeting of AmyI-1-GFP in redifferentiated green cells, and cell biochemical analysis of chloroplastic AmyI-1 demonstrated that AmyI-1 is present in the chloroplasts of rice leaves.…”

mentioning

confidence: 99%

See 2 more Smart Citations

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

et al. 2009

Self Cite

View full text Add to dashboard Cite

The well-characterized secretory glycoprotein, rice (Oryza sativa) a-amylase isoform I-1 (AmyI-1), was localized within the plastids and proved to be involved in the degradation of starch granules in the organelles of rice cells. In addition, a large portion of transiently expressed AmyI-1 fused to green fluorescent protein (AmyI-1-GFP) colocalized with a simultaneously expressed fluorescent plastid marker in onion (Allium cepa) epidermal cells. The plastid targeting of AmyI-1 was inhibited by both dominant-negative and constitutively active mutants of Arabidopsis thaliana ARF1 and Arabidopsis SAR1, which arrest endoplasmic reticulum-to-Golgi traffic. In cells expressing fluorescent trans-Golgi and plastid markers, these fluorescent markers frequently colocalized when coexpressed with AmyI-1. Three-dimensional time-lapse imaging and electron microscopy of high-pressure frozen/freeze-substituted cells demonstrated that contact of the Golgi-derived membrane vesicles with cargo and subsequent absorption into plastids occur within the cells. The transient expression of a series of C-terminal-truncated AmyI-1-GFP fusion proteins in the onion cell system showed that the region from Trp-301 to Gln-369 is necessary for plastid targeting of AmyI-1. Furthermore, the results obtained by site-directed mutations of Trp-302 and Gly-354, located on the surface and on opposite sides of the AmyI-1 protein, suggest that multiple surface regions are necessary for plastid targeting. Thus, Golgi-to-plastid traffic appears to be involved in the transport of glycoproteins to plastids and plastid targeting seems to be accomplished in a sorting signal-dependent manner. INTRODUCTIONCereal a-amylases (EC 3.2.1.1) are typical secretory proteins found in many plants. In germinating cereal seeds, these enzyme molecules are biosynthesized and secreted from the secretory tissues, the scutellar epithelium and the aleurone, to the starchy endosperm, which has undergone programmed cell death. Numerous a-amylase isoforms have been identified in cereals, but the predominant a-amylase isoform I-1 (AmyI-1) in rice (Oryza sativa) is a unique glycoprotein that bears N-linked oligosaccharide side chains (Hayashi et al., 1990;Terashima et al., 1994). The biosynthesis and secretion of AmyI-1 have been extensively investigated: mRNA translation on endoplasmic reticulum (ER) membrane-bound ribosomes, signal sequence-dependent translocation of the ER, core glycosylation in the ER lumen, vesicular transport to the Golgi apparatus, oligosaccharide modification to the complex type, and exocytosis all proceed according to the canonical secretory mechanism (Palade, 1975;Blobel, 1980;Kornfeld and Kornfeld, 1985).Protein targeting into plastids is an essential cellular event for maintaining plant function and plant life. Plastids, including chloroplasts in green leaves and amyloplasts in starchy cells, contain the genetic machinery required to synthesize their own proteins, although most plastidial proteins are encoded in the nuclear DNA. Nuclear-encoded plastidial...

show abstract

Section: Amyi-1 Degrades Starch Granules In Living Rice Cellssupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

et al. 2009

Self Cite

View full text Add to dashboard Cite

show abstract

“…12,34) Asatsuma et al (2006) 35) have reported that ectopic overexpression of AmyI-1 (Amy1A) and AmyII-4 (Amy3D) resulted in grains with decrease weight and chalky appearance even ripened under normal temperature condition. On the other hand, Ishimaru et al (2009) 7) have reported that the α-amylase mRNA was not detected in the central part of endosperm tissue during grain filling, claiming that starch degradation by α-amylase was not the cause of the formation of chalky grain.…”

Section: Breaking Test Of Cooked Rice Of Perfect and Chalky Grainsmentioning

confidence: 99%

Characteristics of Opaque and Translucent Parts of High Temperature Stressed Grains of Rice

et al. 2013

View full text Add to dashboard Cite

Global warming is one of the most serious environmental problems we are having today. The average temperature of Japan actually increased about 1 C during the last 100 years. High temperature stress during rice ripening periods causes a decrease in not only grain yield but also grain appearance quality. The presence or absence of chalk appearance is an important quality characteristic in rice. It is widely known that the occurrence of chalky grains of rice including whitecore, white-belly, white-base and white-back kernels is increased by high temperature stress during grain filling. 1)Several research groups have investigated morphological properties of chalky grains, showing that abnormal starch granules were loosely packed in the chalky grains.2-7) The surface of round-shaped starch granules in the chalky grains caused by high temperature stress had so many small pits.3)Interestingly, the feature of the change of granule surface was similar to that occurring during germination.8) The examination of how the chalkiness of rice grains affects the cooking quality is also an important issue. The chalky grains exhibited their characteristic physicochemical properties of the cooked rice different from those of the perfect grains. [4][5][6][9][10][11] From the obtained results, they mentioned that the cooked/steamed rice of chalky grains had undesirable higher hard texture.12) The mechanism of grain chalkiness under high temperature stress is considerably complicated: disorder of photosynthesis, translocation efficiency, sourcesink relationship, and protein expression in ripening seeds may involve in such chalking mechanism. Interestingly however, it has been shown that the environmental temperature at the grain filling stage influenced the starch composition in rice grains. 5,[11][12][13][14][15][16][17] High temperature stress decreased the amylose contents and altered the fine structure of amylopectin, 13,16) suggesting that the unusual expression of

show abstract

“…On chromosome 8, two high temperature-responsive α-amylase genes, Amy3D and Amy3E, were located in the region corresponding to qPGWC-8 identified in two independent japonica/indica crosses ( Table 2). Since the overexpression of Amy3D in transgenic rice has rendered grains chalky (Asatsuma et al 2006), the indica alleles from Zhai Ye Qing 8 and IR24 in the two crosses might result in stronger expression and/or activity of the product, thus making the endosperm chalky.…”

mentioning

confidence: 99%

Comparison between locations of QTLs for grain chalkiness and genes responsive to high temperature during grain filling on the rice chromosome map

2008

View full text Add to dashboard Cite

.ALPHA.-Amylase Affects Starch Accumulation in Rice Grains

Cited by 39 publications

References 32 publications

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

Characteristics of Opaque and Translucent Parts of High Temperature Stressed Grains of Rice

Comparison between locations of QTLs for grain chalkiness and genes responsive to high temperature during grain filling on the rice chromosome map

Contact Info

Product

Resources

About