[Show abstract][Hide abstract] ABSTRACT: More than half of the world's population uses rice as a source of carbon intake every day. Improving grain quality is thus essential to rice consumers. The three main properties that determine rice eating and cooking quality--amylose content, gel consistency, and gelatinization temperature--correlate with one another, but the underlying mechanism of these properties remains unclear. Through an association analysis approach, we found that genes related to starch synthesis cooperate with each other to form a fine regulating network that controls the eating and cooking quality and defines the correlation among these three properties. Genetic transformation results verified the association findings and also suggested the possibility of developing elite cultivars through modification with selected major and/or minor starch synthesis-related genes.
Full-text · Article · Dec 2009 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: Glycosyltransferases (GTs) are one of the largest enzyme groups required for the synthesis of complex wall polysaccharides and glycoproteins in plants. However, due to the limited number of related mutants that have observable phenotypes, the biological function(s) of most GTs in cell-wall biosynthesis and assembly have remained elusive. We report here the isolation and in-depth characterization of a brittle rice mutant, brittle culm 10 (bc10). bc10 plants show pleiotropic phenotypes, including brittleness of the plant body and retarded growth. The BC10 gene was cloned through a map-based approach, and encodes a Golgi-located type II membrane protein that contains a domain designated as 'domain of unknown function 266' (DUF266) and represents a multiple gene family in rice. BC10 has low sequence similarity with the domain to a core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GnT), and its in vitro enzymatic activity suggests that it functions as a glycosyltransferase. Monosaccharide analysis of total and fractioned wall residues revealed that bc10 showed impaired cellulose biosynthesis. Immunolocalization and isolation of arabinogalactan proteins (AGPs) in the wild-type and bc10 showed that the level of AGPs in the mutant is significantly affected. BC10 is mainly expressed in the developing sclerenchyma and vascular bundle cells, and its deficiency causes a reduction in the levels of cellulose and AGPs, leading to inferior mechanical properties.
Full-text · Article · Nov 2008 · The Plant Journal
[Show abstract][Hide abstract] ABSTRACT: Starch is the major component of cereal grains. In rice, starch properties determine the eating and cooking quality. The dull endosperm of rice grains is a classical morphological and agronomical trait that has long been exploited for breeding and genetics study. To understand the molecular mechanism that regulates the starch biosynthesis in rice grains, we characterized a classic rice mutant dull endosperm1 (du1) and isolated Du1 through a map-based cloning approach. Du1, encoding a member of pre-mRNA processing (Prp1) family, is expressed mainly in panicles. Du1 specifically affects the splicing efficiency of Wx
and regulates starch biosynthesis by mediating the expression of starch biosynthesis genes. Analysis of du1wx shows that Du1 acts upstream of Wx
. These results strongly suggest that Du1 may function as a regulator of the starch biosynthesis by affecting the splicing of Wx
and the expression of other genes involved in the rice starch biosynthetic pathways.
Full-text · Article · Dec 2007 · Plant Molecular Biology
[Show abstract][Hide abstract] ABSTRACT: Polar auxin transport (PAT) plays a crucial role in the regulation of many aspects of plant growth and development. We report the characterization of a semidominant Arabidopsis thaliana bushy and dwarf1 (bud1) mutant. Molecular genetic analysis indicated that the bud1 phenotype is a result of increased expression of Arabidopsis MAP KINASE KINASE7 (MKK7), a member of plant mitogen-activated protein kinase kinase group D. We showed that BUD1/MKK7 is a functional kinase and that the kinase activity is essential for its biological functions. Compared with the wild type, the bud1 plants develop significantly fewer lateral roots, simpler venation patterns, and a quicker and greater curvature in the gravitropism assay. In addition, the bud1 plants have shorter hypocotyls at high temperature (29 degrees C) under light, which is a characteristic feature of defective auxin action. Determination of tritium-labeled indole-3-acetic acid transport showed that the increased expression of MKK7 in bud1 or the repressed expression in MKK7 antisense transgenic plants causes deficiency or enhancement in auxin transport, indicating that MKK7 negatively regulates PAT. This conclusion was further substantiated by genetic and phenotypic analyses of double mutants generated from crosses between bud1 and the auxin-related mutants axr3-3, tir1-1, doc1-1, and atmdr1-1.
[Show abstract][Hide abstract] ABSTRACT: Tiller angle of rice is an important agronomic trait that contributes to breed new varieties with ideal architecture. In this
study, we report mapping and characterization of a rice mutant defective in tiller angle. At the seedling stage, the newly
developed tillers of the mutant plants grow with a large angle that leads to a “lazy” phenotype at the mature stage. Genetic
analysis indicates that this tillerspreading phenotype is controlled by one recessive gene that is allelic to a reported mutantla. Therefore, the mutant was namedla-2 andla renamedla-1. To map and cloneLA, we constructed a large mapping population. Genetic linkage analysis showed that theLA gene is located between 2 SSR markers RM202 and RM229. By using the 6 newly-developed molecular markers, theLA gene was placed within a 0.4 cM interval on chromosome 11, allowing us to cloneLA and study the mechanism that controls rice tiller angle at the molecular level.
Full-text · Article · Dec 2003 · Chinese Science Bulletin
[Show abstract][Hide abstract] ABSTRACT: Tillering in rice (Oryza sativa L.) is an important agronomic trait for grain production, and also a model system for the study of branching in monocotyledonous plants. Rice tiller is a specialized grain-bearing branch that is formed on the unelongated basal internode and grows independently of the mother stem (culm) by means of its own adventitious roots. Rice tillering occurs in a two-stage process: the formation of an axillary bud at each leaf axil and its subsequent outgrowth. Although the morphology and histology and some mutants of rice tillering have been well described, the molecular mechanism of rice tillering remains to be elucidated. Here we report the isolation and characterization of MONOCULM 1 (MOC1), a gene that is important in the control of rice tillering. The moc1 mutant plants have only a main culm without any tillers owing to a defect in the formation of tiller buds. MOC1 encodes a putative GRAS family nuclear protein that is expressed mainly in the axillary buds and functions to initiate axillary buds and to promote their outgrowth.
[Show abstract][Hide abstract] ABSTRACT: An Arabidopsis mosaic death1 (mod1) mutant, which has premature cell death in multiple organs, was isolated. mod1 plants display multiple morphological phenotypes, including chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism. The phenotype of the mod1 mutant results from a single nuclear recessive mutation, and the MOD1 gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reductase, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic activity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants. These results demonstrate that a deficiency in fatty acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.
[Show abstract][Hide abstract] ABSTRACT: There are three non-allelic isogenes encoding phosphoribosylanthranilate isomerase (PAI) inArabidopsis thaliana. The expression plasmids were constructed by fusion of the GUS reporter gene to the three PAI promoters with or without the 5' region encoding PAI N-terminal polypeptides and transferred into Arabidopsis plants byAgrobacterium tumefaciens. Analysis of GUS activity revealed that the PAI 5' coding region was necessary for high expression of GUS activity. GUS activity in transgenic plants transformed with the expression plasmids containing the 5' coding region of PAH or PAI3 was 60-100-fold higher than that without the corresponding 5' region. However, the effect of 5' coding region of PAI2 gene on the GUS activity was very small (only about 1 time difference). The GUS histochemical staining showed a similar result as revealed by GUS activity assay. It was expressed in the mesophyll cells and guard cells, but not in the epidermic cells, indicating that the N-terminal polypeptides encoded by the 5' region of PAI genes have the function of PTP.
No preview · Article · Jun 1999 · Science in China Series C Life Sciences