Rice false smut virulence protein subverts host chitin perception and signaling at lemma and palea for floral infection.

The flower-infecting fungus Ustilaginoidea virens causes rice false smut, which is a severe emerging disease threatening rice (Oryza sativa) production worldwide. False smut not only reduces yield, but more importantly produces toxins on grains, posing a great threat to food safety. U. virens invades spikelets via the gap between the 2 bracts (lemma and palea) enclosing the floret and specifically infects the stamen and pistil. Molecular mechanisms for the U. virens-rice interaction are largely unknown. Here, we demonstrate that rice flowers predominantly employ chitin-triggered immunity against U. virens in the lemma and palea, rather than in the stamen and pistil. We identify a crucial U. virens virulence factor, named UvGH18.1, which carries glycoside hydrolase activity. Mechanistically, UvGH18.1 functions by binding to and hydrolyzing immune elicitor chitin and interacting with the chitin receptor CHITIN ELICITOR BINDING PROTEIN (OsCEBiP) and co-receptor CHITIN ELICITOR RECEPTOR KINASE1 (OsCERK1) to impair their chitin-induced dimerization, suppressing host immunity exerted at the lemma and palea for gaining access to the stamen and pistil. Conversely, pretreatment on spikelets with chitin induces a defense response in the lemma and palea, promoting resistance against U. virens. Collectively, our data uncover a mechanism for a U. virens virulence factor and the critical location of the host-pathogen interaction in flowers and provide a potential strategy to control rice false smut disease.

Golovinomyces cichoracearum effector-associated nuclear localization of RPW8.2 amplifies its expression to boost immunity in Arabidopsis.

Arabidopsis RESISTANCE TO POWDERY MILDEW 8.2 (RPW8.2) is specifically induced by the powdery mildew (PM) fungus (Golovinomyces cichoracearum) in the infected epidermal cells to activate immunity. However, the mechanism of RPW8.2-induction is not well understood. Here, we identify a G. cichoracearum effector that interacts with RPW8.2, named Gc-RPW8.2 interacting protein 1 (GcR8IP1), by a yeast two-hybrid screen of an Arabidopsis cDNA library. GcR8IP1 is physically associated with RPW8.2 with its REALLY INTERESTING NEW GENE finger domain that is essential and sufficient for the association. GcR8IP1 was secreted and translocated into the nucleus of host cell infected with PM. Association of GcR8IP1 with RPW8.2 led to an increase in RPW8.2 in the nucleus. In turn, the nucleus-localized RPW8.2 promoted the activity of the RPW8.2 promoter, resulting in transcriptional self-amplification of RPW8.2 to boost immunity at infection sites. Additionally, ectopic expression or host-induced gene silencing of GcR8IP1 supported its role as a virulence factor in PM. Altogether, our results reveal a mechanism of RPW8.2-dependent defense strengthening via altered partitioning of RPW8.2 and transcriptional self-amplification triggered by a PM fungal effector, which exemplifies an atypical form of effector-triggered immunity.

The false smut pathogen Ustilaginoidea virens requires rice stamens for false smut ball formation.

Rice false smut has emerged as a serious grain disease in rice production worldwide. The disease is characterized by the transformation of individual rice florets into false smut balls, which is caused by the fungal pathogen Ustilaginoidea virens. To date, little is known about the host factors required for false smut ball formation by U. virens. In this study, we identified histological determinants for the formation of false smut balls by inoculating U. virens into rice floral mutants defective with respect to individual floral parts. The results showed that U. virens could form mature false smut balls in rice floral mutants with defective pistils, but failed to develop false smut balls in the superwoman mutant lacking stamens, identifying that U. virens requires rice stamens to complete its infection cycle. Comparative transcriptome analysis indicated a list of candidate host genes that may facilitate nutrient acquisition by U. virens from the rice stamens, such as SWEET11, SWEET14 and SUT5, and genes involved in the biosynthesis of trehalose and raffinose family sugars. These data pinpoint rice stamens as the key target organ of U. virens infection and provide a valuable starting point for dissecting the molecular mechanism of false smut ball formation.

Osa-miR398b boosts H2 O2 production and rice blast disease-resistance via multiple superoxide dismutases.

miRNAs contribute to plant resistance against pathogens. Previously, we found that the function of miR398b in immunity in rice differs from that in Arabidopsis. However, the underlying mechanisms are unclear. In this study, we characterized the mutants of miR398b target genes and demonstrated that multiple superoxide dismutase genes contribute to miR398b-regulated rice immunity against the blast fungus Magnaporthe oryzae. Out of the four target genes of miR398b, mutations in Cu/Zn-Superoxidase Dismutase1 (CSD1), CSD2 and Os11g09780 (Superoxide DismutaseX, SODX) led to enhanced resistance to M. oryzae and increased hydrogen peroxide (H2 O2 ) accumulation. By contrast, mutations in Copper Chaperone for Superoxide Dismutase (CCSD) resulted in enhanced susceptibility. Biochemical studies revealed that csd1, csd2 and sodx displayed altered expression of CSDs and other superoxide dismutase (SOD) family members, leading to increased total SOD enzyme activity that positively contributed to higher H2 O2 production. By contrast, the ccsd mutant showed CSD protein deletion, resulting in decreased CSD and total SOD enzyme activity. Our results demonstrate the roles of different SODs in miR398b-regulated resistance to rice blast disease, and uncover an integrative regulatory network in which miR398b boosts total SOD activity to upregulate H2 O2 concentration and thereby improve disease resistance.

Fluorescence Properties of a Novel Cyanobacteriochrome GAF Domain from Spirulina that Exhibits Moderate Dark Reversion.

Cyanobacteriochromes (CBCRs) are biliproteins for photoreception that are present in cyanobacteria. These proteins possess one or more unique cGMP-specific phosphodiesterase/adenylate cyclase/FhlA (GAF) domains that can covalently bind the linear tetrapyrrole (bilin). Light absorption triggers the photoisomerization of bilin between the 15Z and 15E photostates. The 15E photoproduct of some CBCR GAF domains can revert to the stable 15Z state in the absence of light. In some cases, this property makes these domains function as sensors of light intensity or as red/dark optogenetic switches. However, there have been few reports regarding the applicability of these fluorescent properties. Here, we report a red/green cyanobacteriochrome GAF domain from Spirulina subsalsa, designated SPI1085g3, which exhibited photoconversion from the red-absorbing dark state (Pr, λmax = 642 nm) to the orange-absorbing photoproduct state (Po, λmax = 590 nm), and exhibited moderate dark reversion (t1/2 = 3.3 min) from the Po state to the Pr state. The SPI1085g3 Pr state exhibited intense red fluorescence (λmax = 662 nm), with a quantum yield of 0.14. The fluorescence was switched off by red light irradiation and increased in the dark. Replacement of Cys448 of SPI1085g3 with Ser resulted in a slightly improved fluorescence quantum yield and nearly 13-fold faster dark reversion (t1/2 = 15.2 s) than that of the wild type. This novel red/dark-switchable fluorescent biliprotein expands the present repertoire and diversity of photoswitchable fluorescent protein candidates.

Biosynthesis of Fluorescent ß Subunits of C-Phycocyanin from Spirulina subsalsa in Escherichia coli, and Their Antioxidant Properties.

Phycocyanin, which covalently binds phycocyanobilin chromophores, is not only a candidate fluorescent probe for biological imaging, but also a potential antioxidative agent for healthcare. Herein, a plasmid harboring two cassettes was constructed, with cpcB from Spirulina subsalsa in one cassette and the fusion gene cpcS::ho1::pcyA in the other, and then expressed in Escherichia coli. PCB-CpcB(C-82), a fluorescent phycocyanin ß subunit, was biosynthesized in E. coli, exhibiting an absorption maximum at 620 nm and fluorescence emission maximum at 640 nm. When cpcS was replaced by cpcT, PCB-CpcB(C-153), another fluorescent phycocyanin ß subunit, was produced, exhibiting an absorption maximum at 590 nm and fluorescence emission maximum at 620 nm. These two fluorescent biliproteins showed stronger scavenging activity toward hydroxyl and DPPH free radicals than apo-CpcB. The IC50 values for hydroxyl radical scavenging by PCB-CpcB(C-82), PCB-CpcB(C-153), and apo-CpcB were 38.72 ± 2.48 µg/mL, 51.06 ± 6.74 µg/mL, and 81.82 ± 0.67 µg/mL, respectively, and the values for DPPH radical scavenging were 201.00 ± 5.86 µg/mL, 240.34 ± 4.03 µg/mL, and 352.93 ± 26.30 µg/mL, respectively. The comparative antioxidant capacities of the proteins were PCB-CpcB(C-82) > PCB-CpcB(C-153) > apo-CpcB, due to bilin binding. The two fluorescent biliproteins exhibited a significant effect on relieving the growth of E. coli cells injured by H2O2. The results of this study suggest that the fluorescent phycocyanin ß subunits of S. subsalsa were reconstructed by one expression vector in E. coli, and could be developed as potential antioxidants.

Effects of genome doubling on expression of genes regulating grain size in rice.

Rice is one of the most important staple crops. It has been the major focus in breeding program to improve grain yield. A unique feature of tetraploid rice is the increased grain size and weight compared to diploid. Therefore, investigating the effects of genome doubling on expression of genes regulating grain size is important for yield improvement in rice breeding program. In this study, we analyzed differential expression of six genes regulating grain size in young panicles of various developmental stages between diploid and tetraploid rice. Transgenic approaches were employed to explore the dosage effects on gene expression and grain size. The results showed that genome duplications did not influence the developmental patterns of rice growth, but enhanced plant height, leaf width and grain size. The grain length and width in Indica tetraploid increased significantly, but the grain length showed more obvious change than width in Japonica tetraploid. The expression levels were affected not only by the developmental stages, but also by genetic background. Upon genome doubling, the positive regulation gene GS5 and HGW expression levels were generally higher in tetraploid than the corresponding diploid. Negative regulation gene GS3 in Indica tetraploid tended to be down-regulated or silenced, but increased in Japonica tetraploid. Another negative regulation GW2 was up-regulated in Indica tetraploid and silenced in Japonica tetraploid. The extra copies of GW2 in diploid transgenic lines exerted a gene dosage effect that resulted in the higher expression level than that of wild type diploid and tetraploid, which causes small grain formation in transgenic lines. Our results will help to understand the function of genes regulating the grain size in the diploid and tetraploid, and provide a theoretical basis for yield improvement.

Multiple rice microRNAs are involved in immunity against the blast fungus Magnaporthe oryzae.

MicroRNAs (miRNAs) are indispensable regulators for development and defense in eukaryotes. However, the miRNA species have not been explored for rice (Oryza sativa) immunity against the blast fungus Magnaporthe oryzae, the most devastating fungal pathogen in rice production worldwide. Here, by deep sequencing small RNA libraries from susceptible and resistant lines in normal conditions and upon M. oryzae infection, we identified a group of known rice miRNAs that were differentially expressed upon M. oryzae infection. They were further classified into three classes based on their expression patterns in the susceptible japonica line Lijiangxin Tuan Hegu and in the resistant line International Rice Blast Line Pyricularia-Kanto51-m-Tsuyuake that contains a single resistance gene locus, Pyricularia-Kanto 51-m (Pikm), within the Lijiangxin Tuan Hegu background. RNA-blot assay of nine of them confirmed sequencing results. Real-time reverse transcription-polymerase chain reaction assay showed that the expression of some target genes was negatively correlated with the expression of miRNAs. Moreover, transgenic rice plants overexpressing miR160a and miR398b displayed enhanced resistance to M. oryzae, as demonstrated by decreased fungal growth, increased hydrogen peroxide accumulation at the infection site, and up-regulated expression of defense-related genes. Taken together, our data indicate that miRNAs are involved in rice immunity against M. oryzae and that overexpression of miR160a or miR398b can enhance rice resistance to the disease.

A novel membrane-bound E3 ubiquitin ligase enhances the thermal resistance in plants.

High temperature stress disturbs cellular homoeostasis and results in a severe retardation in crop growth and development. Thus, it is important to reveal the mechanism of plants coping with heat stress. In this study, a novel gene that we identified from Brassica napus, referred to as BnTR1, was found to play a key role in heat stress response in planta. BnTR1 is a membrane-bound RINGv (C4HC3) protein that displays E3 ligase activity in vitro. We demonstrated that modest expression of BnTR1 is sufficient to minimize adverse environmental influence and confers thermal resistance on development without any detrimental effects in B. napus and Oryza sativa. Our investigation into the action mechanism indicates that BnTR1 is likely to be involved in mediating Ca²âº dynamics by regulating the activity of calcium channels, which further alters the transcripts of heat shock factors and heat shock proteins contributing to plant thermotolerance. Hence, our study identified BnTR1 as a novel key factor underlying a conserved mechanism conferring thermal resistance in plants.

A minimal phycobilisome: fusion and chromophorylation of the truncated core-membrane linker and phycocyanin.

Phycobilisomes, the light-harvesting antennas in cyanobacteria and red algae, consist of an allophycocyanin core that is attached to the membrane via a core-membrane linker, and rods comprised of phycocyanin and often also phycoerythrin or phycoerythrocyanin. Phycobiliproteins show excellent energy transfer among the chromophores that renders them biomarkers with large Stokes-shifts absorbing over most of the visible spectrum and into the near infrared. Their application is limited, however, due to covalent binding of the chromophores and by solubility problems. We report construction of a water-soluble minimal chromophore-binding unit of the red-absorbing and fluorescing core-membrane linker. This was fused to minimal chromophore-binding units of phycocyanin. After double chromophorylation with phycocyanobilin, in E. coli, the fused phycobiliproteins absorbed light in the range of 610-660nm, and fluoresced at ~670nm, similar to phycobilisomes devoid of phycoerythr(ocyan)in. The fused phycobiliprotein could also be doubly chromophorylated with phycoerythrobilin, resulting in a chromoprotein absorbing around 540-575nm, and fluorescing at ~585nm. The broad absorptions and the large Stokes shifts render these chromoproteins candidates for imaging; they may also be helpful in studying phycobilisome assembly.

Modular generation of fluorescent phycobiliproteins.

Phycobiliproteins are brightly-fluorescent light-harvesting pigments for photosynthesis in cyanobacteria and red algae. They are also of interest as fluorescent biomarkers, but their heterologous generation in vivo has previously required multiple transformations. We report here a modular approach that requires only two DNA segments. The first codes for the apo-protein. The second codes for fusions capable of chromophore biosynthesis and its covalent attachment to the apo-protein; it contains the genes of heme oxygenase, a bilin reductase, and a chromophore lyase. Phycobiliproteins containing phycoerythrobilin (λ(fluor) ~ 560 nm), phycourobilin (λ(fluor) ~ 500 nm), phycocyanobilin (λ(fluor) ~ 630 nm) or phycoviolobilin (λ(fluor) ~ 580 nm) were obtained in high yield in E. coli. This approach facilitates chromophorylation studies of phycobiliproteins, as well as their use for fluorescence labeling based on their high fluorescence.

Biliverdin incorporation into the cyanobacteriochrome SPI1085g3 from Spirulina.

Cyanobacteriochromes (CBCRs) bind linear tetrapyrrole chromophores, mostly phycocyanobilin (PCB), and exhibit considerable spectral diversity with a high potential for biotechnological applications. Particular attention has been given to the conversion into intrinsic biliverdin (BV) incorporation due to the absence of PCB in mammalian cells. Our recent study discovered that a red/green CBCR of Spirulina subsalsa, SPI1085g3, was covalently attached to PCB and exhibited strong red fluorescence with a unique red/dark switch. In this study, we found that SPI1085g3 could be modestly chromophorylated with BV and absorb somewhat shifted (10 nm) red light, while the single C448S mutant could efficiently bind BV and exhibit unidirectional photoconversion and moderate dark reversion. The fluorescence in its dark-adapted state was switched off by red light, followed by a moderate recovery in the dark, and these were properties similar to those of PCB-binding SPI1085g3. Furthermore, by introducing the CY motif into the conserved CH motif for chromophore attachment, we developed another variant, C448S_CY, which showed increased BV-binding efficiency. As expected, C448S_CY had a significant enhancement in fluorescence quantum yield, reaching that of PCB-binding SPI1085g3 (0.14). These BV-binding CBCRs offer an improved platform for the development of unique photoswitchable fluorescent proteins compared with PCB-binding CBCRs.

Overproduction of OsRACK1A, an effector-targeted scaffold protein promoting OsRBOHB-mediated ROS production, confers rice floral resistance to false smut disease without yield penalty.

Grain formation is fundamental for crop yield but is vulnerable to abiotic and biotic stresses. Rice grain production is threatened by the false smut fungus Ustilaginoidea virens, which specifically infects rice floral organs, disrupting fertilization and seed formation. However, little is known about the molecular mechanisms of the U. virens-rice interaction and the genetic basis of floral resistance. Here, we report that U. virens secretes a cytoplasmic effector, UvCBP1, to facilitate infection of rice flowers. Mechanistically, UvCBP1 interacts with the rice scaffold protein OsRACK1A and competes its interaction with the reduced nicotinamide adenine dinucleotide phosphate oxidase OsRBOHB, leading to inhibition of reactive oxygen species (ROS) production. Although the analysis of natural variation revealed no OsRACK1A variants that could avoid being targeted by UvCBP1, expression levels of OsRACK1A are correlated with field resistance against U. virens in rice germplasm. Overproduction of OsRACK1A restores the OsRACK1A-OsRBOHB association and promotes OsRBOHB phosphorylation to enhance ROS production, conferring rice floral resistance to U. virens without yield penalty. Taken together, our findings reveal a new pathogenic mechanism mediated by an essential effector from a flower-specific pathogen and provide a valuable genetic resource for balancing disease resistance and crop yield.

Chromophorylation of a Novel Cyanobacteriochrome GAF Domain from Spirulina and Its Response to Copper Ions.

Cyanobacteriochromes (CBCRs) are phytochrome-related photoreceptor proteins in cyanobacteria and cover a wide spectral range from ultraviolet to far-red. A single GAF domain that they contain can bind bilin(s) autocatalytically via heterologous recombination and then fluoresce, with potential applications as biomarkers and biosensors. Here, we report that a novel red/green CBCR GAF domain, SPI1085g2 from Spirulina subsalsa, covalently binds both phycocyanobilin (PCB) and phycoerythrobilin (PEB). The PCB-binding GAF domain exhibited canonical red/green photoconversion with weak fluorescence emission. However, the PEB-binding GAF domain, SPI1085g2-PEB, exhibited an intense orange fluorescence (λabs.max = 520 nm, λfluor.max = 555 nm), with a fluorescence quantum yield close to 1.0. The fluorescence of SPI1085g2-PEB was selectively and instantaneously quenched by copper ions in a concentration-dependent manner and exhibited reversibility upon treatment with the metal chelator EDTA. This study identified a novel PEB-binding cyanobacteriochrome-based fluorescent protein with the highest quantum yield reported to date and suggests its potential as a biosensor for the rapid detection of copper ions.

Suppression of rice miR168 improves yield, flowering time and immunity.

MicroRNA168 (miR168) is a key miRNA that targets Argonaute1 (AGO1), a major component of the RNA-induced silencing complex1,2. Previously, we reported that miR168 expression was responsive to infection by Magnaporthe oryzae, the causal agent of rice blast disease3. However, how miR168 regulates immunity to rice blast and whether it affects rice development remains unclear. Here, we report our discovery that the suppression of miR168 by a target mimic (MIM168) not only improves grain yield and shortens flowering time in rice but also enhances immunity to M. oryzae. These results were validated through repeated tests in rice fields in the absence and presence of rice blast pressure. We found that the miR168-AGO1 module regulates miR535 to improve yield by increasing panicle number, miR164 to reduce flowering time, and miR1320 and miR164 to enhance immunity. Our discovery demonstrates that changes in a single miRNA enhance the expression of multiple agronomically important traits.

[Imprinting genes and it's expression in Arabidopsis].

Genomic imprinting refers to the phenomenon that the expression of a gene copy depends on its parent of origin. The Arabidopsis imprinted FIS (Fertilisation-independent seed) genes, mea, fis2, and fie, play essential roles in the repression of central cell and the regulation of early endosperm development. fis mutants display two phenotypes: autonomous diploid endosperm development when fertilization is absent and un-cellularised endosperm formation when fertilization occurs. The FIS Polycomb protein complex including the above three FIS proteins catalyzes histone H3 K27 tri-methylation on target loci. DME (DEMETER), a DNA glycosylase, and AtMET1 (Methyltransferase1), a DNA methyltransferase, are involved in the regulation of imprinted expression of both mea and fis2. This review summarizes the studies on the Arabidopsis imprinted FIS genes and other related genes. Recent works have shown that the insertion of transposons may affect nearby gene expression, which may be the main driving force behind the evolution of genomic imprinting. This summary covers the achievements on Arabidopsis imprinted genes will provide important information for studies on genomic imprinting in the important crops such as rice and maize.

[cDNA-AFLP analysis among different organs of haploid and diploid plants in twin-seedling rice].

SARII-628 is one of the natural twin-seedling populations, which are maintained in Rice Institution of Sichuan Agricultural University. Haploid-diploid (n: 2n) twin-seedlings can annually emerge from SARII-628. In this study, cDNA-AFLP technique was applied for these haploid and diploid plants. The double stranded cDNA were synthesized from the total RNAs of the roots, stems, panicles, and leaves of three haploid and one diploid plants. Then, EcoRI/MspI combination was chosen for expression difference analysis with cDNA-AFLP technique among the 16 samples. Thirty pairs of primers were selected to amplify 633 loci. Among them, 49 loci were differently expressed. As shown by cDNA-AFLP, the expression levels of haploids were different among individuals but not significant. The average ratio of sensitive loci (activated loci + silenced loci) in haploids was 5.14%, which was higher than that of diploid (3.93%). According to the presence or absence of the bands in root, stem, panicle, and leaf, out of the 14 types of amplified patterns, only 4 exclusively occurred in haploid and the corresponding loci were thus haploid-specific in expression. The collecting analysis for the silenced and activated loci among different organs of the three haploids revealed that the silenced loci were more than the activated ones in roots and panicles. An opposite trend was observed in panicles and leaves. However, the total number of the activated loci in all the four types of haploid organs was more than that of the silenced loci. The number of sensitive loci is the highest in root, while that in panicle is the least, which suggested that gene expressions were organ-specific.

Systematic Investigation of Quercetin for Treating Cardiovascular Disease Based on Network Pharmacology.

AIM AND OBJECTIVE: Cardiovascular disease is a serious threat to human health because of its high mortality and morbidity rates. At present, there is no effective treatment. In Southeast Asia, traditional Chinese medicine is widely used in the treatment of cardiovascular diseases. Quercetin is a flavonoid extract of Ginkgo biloba leaves. Basic experiments and clinical studies have shown that quercetin has a significant effect on the treatment of cardiovascular diseases. However, its precise mechanism is still unclear. Therefore, it is necessary to exploit the network pharmacological potential effects of quercetin on cardiovascular disease. MATERIALS AND METHODS: In the present study, a novel network pharmacology strategy based on pharmacokinetic filtering, target fishing, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, compound-target-pathway network structured was performed to explore the anti- cardiovascular disease mechanism of quercetin. RESULTS: The outcomes showed that quercetin possesses favorable pharmacokinetic profiles, which have interactions with 47 cardiovascular disease-related targets and 12 KEGG signaling pathways to provide potential synergistic therapeutic effects. Following the construction of Compound-Target-Pathway (C-T-P) network, and the network topological feature calculation, we obtained top 10 core genes in this network which were AKT1, IL1B, TNF, IL6, JUN, CCL2, FOS, VEGFA, CXCL8, and ICAM1. KEGG pathway enrichment analysis. These indicated that quercetin produced the therapeutic effects against cardiovascular disease by systemically and holistically regulating many signaling pathways, including Fluid shear stress and atherosclerosis, AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, MAPK signaling pathway, IL-17 signaling pathway and PI3K-Akt signaling pathway.

Phenotypic characterization, genetic analysis and gene-mapping for a brittle mutant in rice.

Plant mechanical strength is an important agronomic trait of rice. An ethyl methane sulfonate (EMS)-induced rice mutant, fragile plant 2 (fp2), showed morphological changes and reduced mechanical strength. Genetic analysis indicated that the brittle of fp2 was controlled by a recessive gene. The fp2 gene was mapped on chromosome 10. Anatomical analyses showed that the fp2 mutation caused the reduction of cell length and cell wall thickness, increasing of cell width, and the alteration of cell wall structure as well as the vessel elements. The consequence was a global alteration in plant morphology. Chemical analyses indicated that the contents of cellulose and lignin decreased, and hemicelluloses and silicon increased in fp2. These results were different from the other mutants reported in rice. Thus, fp2 might affect the deposition and patterning of microfibrils, the biosynthesis and deposition of cell wall components, which influences the formation of primary and secondary cell walls, the thickness of cell walls, cell elongation and expansion, plant morphology and plant strength in rice.

Genetic analysis and histological study of red seed in rice.

Reciprocal crosses between red and achromatic rice revealed that the seed color of F1 was determined by its female parent. According to the seed color and plant segregation ratio of F1, F2, and F3 generations, the red phenotype of red double-haploid seed was determined by a dominant, monogene with maternal effect. Histological study showed that the red pigments accumulated in the pericarp layer only. The assay of developmental timing of pigment accumulation showed that the red color accumulated from desiccation stage to perfectly maturation stage of the seeds.