Publications by authors named "Zongxiang Chen"

19 Publications

  • Page 1 of 1

Genome-Wide Association Analysis for Salt-Induced Phenotypic and Physiologic Responses in Rice at Seedling and Reproductive Stages.

Front Plant Sci 2022 9;13:822618. Epub 2022 Feb 9.

Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou, China.

Salinity is one of the main adverse environmental factors severely inhibiting rice growth and decreasing grain productivity. Developing rice varieties with salt tolerance (ST) is one of the most economical approaches to cope with salinity stress. In this study, the salt tolerance of 220 rice accessions from rice diversity panel l (RDP1), representing five subpopulations, were evaluated based on 16 ST indices at both seedling and reproductive stages under salt stress. An apparent inconsistency was found for ST between the two stages. Through a gene-based/tightly linked genome-wide association study with 201,332 single nucleotide polymorphisms (SNPs) located within genes and their flanking regions were used, a total of 214 SNPs related to 251 genes, significantly associated with 16 ST-related indices, were detected at both stages. Eighty-two SNPs with low frequency favorable (LFF) alleles in the population were proposed to hold high breeding potential in improving rice ST. Fifty-four rice accessions collectively containing all these LFF alleles were identified as donors of these alleles. Through the integration of meta-quantitative trait locus (QTL) for ST and the response patterns of differential expression genes to salt stress, thirty-eight candidate genes were suggested to be involved in the regulation of rice ST. In total, the present study provides valuable information for further characterizing ST-related genes and for breeding ST varieties across whole developmental stages through marker-assisted selection (MAS).
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http://dx.doi.org/10.3389/fpls.2022.822618DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8863738PMC
February 2022

Efficient mutagenesis targeting the gene in mice using a combination of Cas9 protein and dual gRNAs.

Am J Transl Res 2021 15;13(10):12094-12106. Epub 2021 Oct 15.

Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University Nanjing 210046, Jiangsu, China.

We injected mouse zygotes with combinations of Cas9 protein, mRNA, and two gRNAs targeting a single exon of type I interferon receptor () to determine the gene targeting efficiencies. Cas9 protein produced on-target mutations more efficiently than mRNA when each was used with a single gRNA, regardless of which gRNA was used. When mRNA and Cas9 protein were co-injected, the on-target efficiency could reach 97.0% when both gRNAs were used, which was higher than when either gRNA was used alone (61.3% and 75.5%, respectively; P<0.05). Co-injection of Cas9 protein with both gRNAs produced the highest on-target mutation rate of any combination (100.0%). Most on-target mutations were deletions of 2 to 113 nucleotides, and there were few off-target mutations in mutant animals. The expression intensity of IFNAR1 was reduced in heterozygous mice (IF) and almost or completely absent in homozygous null mice compared with that in wild-type mice (IF and Western blot). When both gRNAs targeting were used simultaneously with two gRNAs targeting , the on-target editing efficiency on each gene was 96.8% and 85.5%, respectively. Co-injection of dual gRNAs and Cas9 protein is an efficient approach for knockout and multi-gene editing in mice and may be applied in other animal models and breeding livestock.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8581890PMC
October 2021

Suppressing chlorophyll degradation by silencing OsNYC3 improves rice resistance to Rhizoctonia solani, the causal agent of sheath blight.

Plant Biotechnol J 2022 02 20;20(2):335-349. Epub 2021 Oct 20.

Key Laboratory of Plant Functional Genomics of The Ministry of Education, Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou, China.

Necrotrophic fungus Rhizoctonia solani Kühn (R. solani) causes serious diseases in many crops worldwide, including rice and maize sheath blight (ShB). Crop resistance to the fungus is a quantitative trait and resistance mechanism remains largely unknown, severely hindering the progress on developing resistant varieties. In this study, we found that resistant variety YSBR1 has apparently stronger ability to suppress the expansion of R. solani than susceptible Lemont in both field and growth chamber conditions. Comparison of transcriptomic profiles shows that the photosynthetic system including chlorophyll biosynthesis is highly suppressed by R. solani in Lemont but weakly in YSBR1. YSBR1 shows higher chlorophyll content than that of Lemont, and inducing chlorophyll degradation by dark treatment significantly reduces its resistance. Furthermore, three rice mutants and one maize mutant that carry impaired chlorophyll biosynthesis all display enhanced susceptibility to R. solani. Overexpression of OsNYC3, a chlorophyll degradation gene apparently induced expression by R. solani infection, significantly enhanced ShB susceptibility in a high-yield ShB-susceptible variety '9522'. However, silencing its transcription apparently improves ShB resistance without compromising agronomic traits or yield in field tests. Interestingly, altering chlorophyll content does not affect rice resistance to blight and blast diseases, caused by biotrophic and hemi-biotrophic pathogens, respectively. Our study reveals that chlorophyll plays an important role in ShB resistance and suppressing chlorophyll degradation induced by R. solani infection apparently improves rice ShB resistance. This discovery provides a novel target for developing resistant crop to necrotrophic fungus R. solani.
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http://dx.doi.org/10.1111/pbi.13715DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8753359PMC
February 2022

Development of marker-free rice with stable and high resistance to rice black-streaked dwarf virus disease through RNA interference.

Plant Biotechnol J 2021 02 17;19(2):212-214. Epub 2020 Aug 17.

Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou, China.

The rice black-streaked dwarf virus (RBSDV) disease causes severe rice yield losses in Asia. RNA interference (RNAi) has been widely applied to develop antiviral varieties in plants. So far, only a few studies reported the application of RNAi in rice against RBSDV and most of them are lack of enough data to support its breeding potential, which limited the progress on developing RBSDV-resistant variety. In this study, we generated three RNAi constructs to specifically target three RBSDV genes (S1, S2 and S6), respectively. We confirmed that RNAi targeting RBSDV S6 conferred rice with almost full immunity to RBSDV through phenotyping test in eight consecutive years in both artificial inoculation and field trials, while RNAi of S1 or S2 only leads to partially increased resistance. The S6RNAi was also found conferring strong resistance to southern rice black-streaked dwarf virus (SRBSDV), a novel species closely related to RBSDV that outbroke recently in Southern China. In particular, no adverse effects on agronomical and developmental traits were found in S6RNAi transgenic lines. The marker-free transgenic lines with S6RNAi, driven by either maize ubiquitin-1 promoter or rice rbcS green tissue expression promoter, in elite rice background should have great potential in breeding of resistant varieties to both RBSDV and SRBSDV and provide a basis for further safety evaluation and commercial application.
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http://dx.doi.org/10.1111/pbi.13459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868976PMC
February 2021

COL6A1 knockdown suppresses cell proliferation and migration in human aortic vascular smooth muscle cells.

Exp Ther Med 2019 Sep 19;18(3):1977-1984. Epub 2019 Jul 19.

Emergency Department, Jining 1 People's Hospital, Jining, Shandong 272011, P.R. China.

Vascular smooth muscle cell (VSMC) migration is an important pathophysiological signature of neointimal hyperplasia. The aim of the present study was to investigate the effects of collagen type VI α1 chain (COL6A1) on VSMC migration. COL6A1 expression was silenced in platelet-derived growth factor (PDGF-BB)-stimulated VSMCs. Cell counting kit-8, wound healing and Transwell assays were used to measure cell viability, migration and invasion, respectively. Reverse transcription-quantitative PCR and western blot analysis were performed to analyze the expression of factors associated with metastasis. COL6A1 silencing attenuated PDGF-BB-induced increases in cell viability and invasive abilities of VSMCs, in addition to partially reversing the increased expression of fibronectin (FN), matrix metalloproteinase (MMP)-2 and MMP-9 induced by PDGF-BB stimulation. The silencing of COL6A also overturned PDGF-BB-induced reduction in tissue inhibitor of metalloproteinase 2 expression in VSMCs. PDGF-BB activated the AKT/mTOR pathway, which was also inhibited by COL6A1 knockdown. Taken together, these findings suggest that COL6A1 silencing inhibited VSMC viability and migration by inhibiting AKT/mTOR activation.
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http://dx.doi.org/10.3892/etm.2019.7798DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6676143PMC
September 2019

Identification of new rice cultivars and resistance loci against rice black-streaked dwarf virus disease through genome-wide association study.

Rice (N Y) 2019 Jul 15;12(1):49. Epub 2019 Jul 15.

Jiangsu Key Laboratory of Crop Genetics and Physiology/ Key Laboratory of Plant Functional Genomics of the Ministry of Education/ Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou, 225009, China.

Background: The rice black-streaked dwarf virus (RBSDV) disease causes severe rice yield losses in Eastern China and other East Asian countries. Breeding resistant cultivars is the most economical and effective strategy to control the disease. However, few varieties and QTLs for RBSDV resistance have been identified to date.

Results: In this study, we conducted a genome-wide association study (GWAS) on RBSDV resistance using the rice diversity panel 1 (RDP1) cultivars that were genotyped by a 44,000 high-density single nucleotide polymorphism (SNP) markers array. We found that less than 15% of these cultivars displayed resistance to RBSDV when tested under natural infection conditions at two locations with serious RBSDV occurrence. The aus, indica and tropical japonica sub-populations displayed higher RBSDV resistance than the aromatic and temperate japonica sub-populations. In particular, we identified four varieties that displayed stable levels of RBSDV resistance at all testing locations. GWAS identified 84 non-redundant SNP loci significantly associated with RBSDV resistance at two locations, leading to the identification of 13 QTLs for RBSDV resistance. Among them, qRBSDV-4.2 and qRBSDV-6.3 were detected at both locations, suggesting their resistance stability against environmental influence. Field disease evaluations showed that qRBSDV-6.3 significantly reduces RBSDV disease severity by 20%. Furthermore, introgression of qRBSDV-6.3 into two susceptible rice cultivars by marker-assisted selection demonstrated the effectiveness of qRBSDV-6.3 in enhancing RBSDV resistance.

Conclusions: The new resistant cultivars and QTLs against RBSDV disease identified in this study provide important information and genetic materials for the cloning of RBSDV resistance genes as well as developing RBSDV resistant varieties through marker-assisted selection.
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http://dx.doi.org/10.1186/s12284-019-0310-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629753PMC
July 2019

Author Correction: Toxicity evaluation of Wanzhou watershed of Yangtze Three Gorges Reservoir in the flood season in Caenorhabditis elegans.

Sci Rep 2018 Oct 18;8(1):15652. Epub 2018 Oct 18.

Medical School, Southeast University, Nanjing, 210009, China.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
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http://dx.doi.org/10.1038/s41598-018-34064-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6194054PMC
October 2018

Author Correction: Biosafety assessment of water samples from Wanzhou watershed of Yangtze Three Gorges Reservoir in the quiet season in Caenorhabditis elegans.

Sci Rep 2018 Oct 17;8(1):15589. Epub 2018 Oct 17.

Medical School, Southeast University, Nanjing, 210009, China.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
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http://dx.doi.org/10.1038/s41598-018-34066-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6193032PMC
October 2018

Biosafety assessment of water samples from Wanzhou watershed of Yangtze Three Gorges Reservior in the quiet season in Caenorhabditis elegans.

Sci Rep 2018 09 20;8(1):14102. Epub 2018 Sep 20.

Medical School, Southeast University, Nanjing, 210009, China.

We here employed a model animal of Caenorhabditis elegans to perform toxicity assessment of original surface water samples collected from Three Gorges Reservoir (TGR) in the quiet season in Wanzhou, Chongqing. Using some sublethal endpoints, including lifespan, body length, locomotion behavior, brood size, and intestinal reactive oxygen species (ROS) induction, we found that the examined five original surface water samples could not cause toxicity on wild-type nematodes. Nevertheless, the surface water sample collected from backwater area induced the significant increase in expressions of genes (sod-2 and sod-3) encoding Mn-SODs in wild-type nematodes. Among the examined five original surface water samples, exposure to the original surface water sample collected from backwater area could further cause the toxicity in decreasing locomotion behavior and in inducing intestinal ROS production in sod-3 mutant nematodes. Moreover, the solid phase of surface water sample collected from backwater area might mainly contribute to the observed toxicity in sod-3 mutant nematodes. Our results are helpful for understanding the potential effects of surface water in the TGR region in the quiet season on environmental organisms.
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http://dx.doi.org/10.1038/s41598-018-32296-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6148280PMC
September 2018

Toxicity evaluation of Wanzhou watershed of Yangtze Three Gorges Reservior in the flood season in Caenorhabditis elegans.

Sci Rep 2018 04 30;8(1):6734. Epub 2018 Apr 30.

Medical School, Southeast University, Nanjing, 210009, China.

Three Gorges Reservoir (TGR) in the upper stream of Yangtze River in China is a reservoir with the largest and the longest yearly water-level drop. Considering the fact that most of safety assessments of water samples collected from TGR region were based on chemical analysis, we here employed Caenorhabditis elegans to perform in vivo safety assessment of original surface water samples collected from TGR region in the flood season in Wanzhou, Chongqing. Among the examined five original surface water samples, only exposure to original surface water sample collected from backwater area could induce the significant intestinal ROS production, enhance the intestinal permeability, and decrease the locomotion behavior. Additionally, exposure to original surface water sample collected from backwater area altered the expressions of sod-2, sod-5, clk-1, and mev-1. Moreover, mutation of sod-2 or sod-5 was susceptible to the potential toxicity of original surface water sample collected from backwater area on nematodes. Together, our results imply that exposure to surface water sample from the backwater area may at least cause the adverse effects on intestinal function and locomotion behavior in nematodes.
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http://dx.doi.org/10.1038/s41598-018-25048-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5928115PMC
April 2018

Leptin receptor gene polymorphisms and risk of hypertension: a meta-analysis.

Int J Clin Exp Med 2015 15;8(8):14277-82. Epub 2015 Aug 15.

Department of Emergency, Jining First People's Hospital China.

Objective: To assess the relationship between the polymorphisms of leptin receptor gene and hypertension.

Methods: Meta analysis was conducted by using RevMan 5.3. Relevant literatures were retrieved by searching PubMed using the keywords "Hypertension", "Leptin Receptor", "OB Receptor", "LEPR Protein".

Results: Fifteen studies with a total of 5955 patients with hypertension and 3830 healthy controls were included in this meta-analysis. The results showed that Gln223Arg gene polymorphism was significantly higher in hypertension patients than in control (OR=1.36, 95% CI=1.23-1.51, P<0.00001). However, no statistically significant difference was found in Lys109Arg polymorphism between hypertension patients and control (OR=0.99, 95% CI=0.85-1.16, P=0.91).

Conclusion: Gln223Arg, but not Lys109Arg gene polymorphism, is higher in hypertension patients, suggesting that patients with Gln223Arg allele carry a higher risk to develop hypertension.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613096PMC
November 2015

Preparation of ALG-g-Lys and its application as a novel drug carrier.

J Mater Chem B 2015 May 13;3(17):3420-3424. Epub 2015 Apr 13.

College of Chemical Engineering, Huaqiao University, Xiamen, China.

In order to improve alginate microbead stability and further broaden the application of alginate in biomaterials, a new biomaterial, ALG-g-Lys, was prepared and its possibility as a novel drug carrier investigated. The carrier exhibited a sustained release property and preserved activity with no initial burst release, and interestingly, GP-crosslinked ALG-g-Lys microspheres showed obvious fluorescence properties, which showed promising potential for the future drug delivery systems.
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http://dx.doi.org/10.1039/c5tb00410aDOI Listing
May 2015

Identification of Two Major Rice Sheath Blight Resistance QTLs, qSB1-1 and qSB11, in Field Trials Using Chromosome Segment Substitution Lines.

Plant Dis 2014 Aug;98(8):1112-1121

The Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, The Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China.

Sheath blight (SB) is among the most destructive rice (Oryza sativa) diseases worldwide. SB resistance (SBR) is controlled by quantitative trait loci (QTL). Only a few SB resistance QTLs were confirmed previously in field trials that were independent of morphological traits, a crucial factor in plant breeding. Here, we employed 63 chromosome segment substitution lines (CSSLs) to identify SBR QTLs derived from 'HJX74'. Importantly, these CSSLs all carried the same genetic background as 'HJX74', except in the substituted segment introgressed from susceptible 'Amol3(sona)'. In contrast to most reports that mapped SBR QTLs under complex genetic backgrounds, this approach allowed many CSSLs to consistently retain the agronomic traits of 'HJX74' with moderate resistance, giving the needed high reproducibility in SBR scoring. We have identified five SBR QTLs in field tests. Two of them, qSB11 and qSB1-1, conferred the greatest reduction in SB ratings by approximately 0.9 to 1.2 on a 0 to 9 scale. qSB11 exhibited nearly perfect recessive heredity, whereas qSB1-1 showed dominant heredity. Using a secondary F population and overlapping substitution segment lines, we further mapped qSB11 and qSB1-1 to regions of approximately 430 and 930 kb, respectively. The results will accelerate the rice breeding process for resistance to SB disease.
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http://dx.doi.org/10.1094/PDIS-10-13-1095-REDOI Listing
August 2014

Identification and functional analysis of flowering related microRNAs in common wild rice (Oryza rufipogon Griff.).

PLoS One 2013 30;8(12):e82844. Epub 2013 Dec 30.

Institute of Biotechnology, Chinese Academy of Agricultural Sciences, Beijing, China.

Background: MicroRNAs (miRNAs) is a class of non-coding RNAs involved in post- transcriptional control of gene expression, via degradation and/or translational inhibition. Six-hundred sixty-one rice miRNAs are known that are important in plant development. However, flowering-related miRNAs have not been characterized in Oryza rufipogon Griff. It was approved by supervision department of Guangdong wild rice protection. We analyzed flowering-related miRNAs in O. rufipogon using high-throughput sequencing (deep sequencing) to understand the changes that occurred during rice domestication, and to elucidate their functions in flowering.

Results: Three O. rufipogon sRNA libraries, two vegetative stage (CWR-V1 and CWR-V2) and one flowering stage (CWR-F2) were sequenced using Illumina deep sequencing. A total of 20,156,098, 21,531,511 and 20,995,942 high quality sRNA reads were obtained from CWR-V1, CWR-V2 and CWR-F2, respectively, of which 3,448,185, 4,265,048 and 2,833,527 reads matched known miRNAs. We identified 512 known rice miRNAs in 214 miRNA families and predicted 290 new miRNAs. Targeted functional annotation, GO and KEGG pathway analyses predicted that 187 miRNAs regulate expression of flowering-related genes. Differential expression analysis of flowering-related miRNAs showed that: expression of 95 miRNAs varied significantly between the libraries, 66 are flowering-related miRNAs, such as oru-miR97, oru-miR117, oru-miR135, oru-miR137, et al. 17 are early-flowering -related miRNAs, including osa-miR160f, osa-miR164d, osa-miR167d, osa-miR169a, osa-miR172b, oru-miR4, et al., induced during the floral transition. Real-time PCR revealed the same expression patterns as deep sequencing. miRNAs targets were confirmed for cleavage by 5'-RACE in vivo, and were negatively regulated by miRNAs.

Conclusions: This is the first investigation of flowering miRNAs in wild rice. The result indicates that variation in miRNAs occurred during rice domestication and lays a foundation for further study of phase change and flowering in O. rufipogon. Complicated regulatory networks mediated by multiple miRNAs regulate the expression of flowering genes that control the induction of flowering.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0082844PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3875430PMC
September 2014

Fine mapping of qSB-11(LE), the QTL that confers partial resistance to rice sheath blight.

Theor Appl Genet 2013 May 20;126(5):1257-72. Epub 2013 Feb 20.

Key Lab of Plant Functional Genomics, Ministry of Education, Yangzhou University, Yangzhou 225009, People's Republic of China.

Sheath blight (SB), caused by Rhizoctonia solani kühn, is one of the most serious global rice diseases. No major resistance genes to SB have been identified so far. All discovered loci are quantitative resistance to rice SB. The qSB-11(LE) resistance quantitative trait locus (QTL) has been previously reported on chromosome 11 of Lemont (LE). In this study, we report the precise location of qSB-11 (LE) . We developed a near isogenic line, NIL-qSB11(TQ), by marker-assisted selection that contains susceptible allele(s) from Teqing (TQ) at the qSB-11 locus in the LE genetic background. NIL-qSB11(TQ) shows higher susceptibility to SB than LE in both field and greenhouse tests, suggesting that this region of LE contains a QTL contributing to SB resistance. In order to eliminate the genetic background effects and increase the accuracy of phenotypic evaluation, a total of 112 chromosome segment substitution lines (CSSLs) with the substituted segment specific to the qSB-11 (LE) region were produced as the fine mapping population. The genetic backgrounds and morphological characteristics of these CSSLs are similar to those of the recurrent parent LE. The donor TQ chromosomal segments in these CSSL lines contiguously overlap to bridge the qSB-11 (LE) region. Through artificial inoculation, all CSSLs were evaluated for resistance to SB in the field in 2005. For the recombinant lines, their phenotypes were evaluated in the field for another 3 years and during the final year were also evaluated in a controlled greenhouse environment, showing a consistent phenotype in SB resistance across years and conditions. After comparing the genotypic profile of each CSSL with its phenotype, we are able to localize qSB-11 (LE) to the region defined by two cleaved-amplified polymorphic sequence markers, Z22-27C and Z23-33C covering 78.871 kb, based on the rice reference genome. Eleven putative genes were annotated within this region and three of them were considered the most likely candidates. The results of this study will greatly facilitate the cloning of the genes responsible for qSB-11 (LE) and marker-assisted breeding to incorporate qSB-11 (LE) into other rice cultivars.
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http://dx.doi.org/10.1007/s00122-013-2051-7DOI Listing
May 2013

Association between seed dormancy and pericarp color is controlled by a pleiotropic gene that regulates abscisic acid and flavonoid synthesis in weedy red rice.

Genetics 2011 Dec 27;189(4):1515-24. Epub 2011 Sep 27.

Plant Science Department, South Dakota State University, Brookings, South Dakota 57007, USA.

Seed dormancy has been associated with red grain color in cereal crops for a century. The association was linked to qSD7-1/qPC7, a cluster of quantitative trait loci for seed dormancy/pericarp color in weedy red rice. This research delimited qSD7-1/qPC7 to the Os07g11020 or Rc locus encoding a basic helix-loop-helix family transcription factor by intragenic recombinants and provided unambiguous evidence that the association arises from pleiotropy. The pleiotropic gene expressed in early developing seeds promoted expression of key genes for biosynthesis of abscisic acid (ABA), resulting in an increase in accumulation of the dormancy-inducing hormone; activated a conserved network of eight genes for flavonoid biosynthesis to produce the pigments in the lower epidermal cells of the pericarp tissue; and enhanced seed weight. Thus, the pleiotropic locus most likely controls the dormancy and pigment traits by regulating ABA and flavonoid biosynthetic pathways, respectively. The dormancy effect could be eliminated by a heat treatment, but could not be completely overcome by gibberellic acid or physical removal of the seed maternal tissues. The dormancy-enhancing alleles differentiated into two groups basically associated with tropical and temperate ecotypes of weedy rice. Of the pleiotropic effects, seed dormancy could contribute most to the weed adaptation. Pleiotropy prevents the use of the dormancy gene to improve resistance of white pericarp cultivars against pre-harvest sprouting through conventional breeding approaches.
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http://dx.doi.org/10.1534/genetics.111.131169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3241415PMC
December 2011

Fine mapping of qSTV11TQ, a major gene conferring resistance to rice stripe disease.

Theor Appl Genet 2011 Mar 8;122(5):915-23. Epub 2010 Dec 8.

Key Laboratory of Plant Functional Genomics, Ministry of Education, Yangzhou University, Yangzhou, People's Republic of China.

The indica rice cultivar, Teqing, shows a high level of resistance to rice stripe virus (RSV). It is believed that this resistance is controlled by the gene, qSTV11(TQ). For positional cloning of the resistance gene, a set of chromosome single segment substitution lines (CSSSLs) was constructed, all of which had the genetic background of the susceptible japonica cultivar, Lemont, with different single substituted segments of Teqing on chromosome 11. By identifying the resistance of the CSSSLs-2006 in a field within a heavily diseased area, the resistance gene qSTV11(TQ) was mapped between the markers Indel7 and RM229. Furthermore, in that region, six new markers were developed and 52 subregion CSSSLs (CSSSLs-2007) were constructed. The natural infection experiment was conducted again at different sites, with two replicates used in each site in order to identify the resistance phenotypes of the CSSSLs-2007 and resistant/susceptible controls in 2007. Through the results of 2007, qSTV11(TQ) was localized in a region defined by the markers, CAPs1 and Indel4. In order to further confirm the position of qSTV11(TQ), another set of subregion CSSSLs (CSSSLs-2009) was constructed. Finally, qSTV11(TQ) was localized to a 55.7 kb region containing nine annotated genes according to the genome sequence of japonica Nipponbare. The relationship between qSTV11(TQ) and Stvb-i (Hayano-Saito et al. in Theor Appl Genet 101:59-63, 2000) and the reliability of the markers used on both sides of qSTV11(TQ) for marker-assisted breeding of resistance to rice stripe disease are discussed.
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http://dx.doi.org/10.1007/s00122-010-1498-zDOI Listing
March 2011

Prospect of the QTL-qSB-9Tq utilized in molecular breeding program of japonica rice against sheath blight.

J Genet Genomics 2008 Aug;35(8):499-505

Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, China.

The major QTL-qSB-9(Tq) conferring partial resistance to rice (Oryza sativa L.) sheath blight (Rhizoctonia solani Kühn) has been verified on chromosome 9 of the indica rice cultivar, Teqing. In this study, the prospect of this QTL utilized in molecular breeding program of japonica rice for sheath blight resistance was investigated. Most of the japonica rice cultivars showed lower level of sheath blight resistance than the indica rice cultivars. At the corresponding site of qSB-9(Tq), nine typical japonica rice cultivars from different ecological regions or countries proved to possess the susceptible allele(s). Introgression of qSB-9(Tq) into these cultivars enhanced their resistance level by decreasing sheath blight score of 1.0 (0.5-1.3), which indicated that qSB-9(Tq) had a large potential in strengthening the resistance of japonica rice to sheath blight. The use of the three molecular markers, which were polymorphic between Teqing and many japonica rice cultivars, promotes the application of qSB-9(Tq) in a concrete molecular breeding program.
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http://dx.doi.org/10.1016/S1673-8527(08)60068-5DOI Listing
August 2008

The rice HIGH-TILLERING DWARF1 encoding an ortholog of Arabidopsis MAX3 is required for negative regulation of the outgrowth of axillary buds.

Plant J 2006 Dec 8;48(5):687-98. Epub 2006 Nov 8.

State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

Rice tillering is an important agronomic trait for grain production. The HIGH-TILLERING DWARF1 (HTD1) gene encodes an ortholog of Arabidopsis MAX3. Complementation analyses for HTD1 confirm that the defect in HTD1 is responsible for both high-tillering and dwarf phenotypes in the htd1 mutant. The rescue of the Arabidopsis max3 mutant phenotype by the introduction of Pro(35S):HTD1 indicates HTD1 is a carotenoid cleavage dioxygenase that has the same function as MAX3 in synthesis of a carotenoid-derived signal molecule. The HTD1 gene is expressed in both shoot and root tissues. By evaluating Pro(HTD1):GUS expression, we found that the HTD1 gene is mainly expressed in vascular bundle tissues throughout the plant. Auxin induction of HTD1 expression suggests that auxin may regulate rice tillering partly through upregulation of HTD1 gene transcription. Restoration of dwarf phenotype after the removal of axillary buds indicates that the dwarfism of the htd1 mutant may be a consequence of excessive tiller production. In addition, the expression of HTD1, D3 and OsCCD8a in the htd1 and d3 mutants suggests a feedback mechanism may exist for the synthesis and perception of the carotenoid-derived signal in rice. Characterization of MAX genes in Arabidopsis, and identification of their orthologs in pea, petunia and rice indicates the existence of a conserved mechanism for shoot-branching regulation in both monocots and dicots.
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http://dx.doi.org/10.1111/j.1365-313X.2006.02916.xDOI Listing
December 2006
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