Publications by authors named "Dagang Tian"

14 Publications

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The Interaction between Rice Genotype and Magnaporthe oryzae Regulates the Assembly of Rice Root-Associated Microbiota.

Rice (N Y) 2021 May 11;14(1):40. Epub 2021 May 11.

State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, China.

Background: Utilizating the plant microbiome to enhance pathogen resistance in crop production is an emerging alternative to the use of chemical pesticides. However, the diversity and structure of the microbiota, and the assembly mechanisms of root-associated microbial communities of plants are still poorly understood.

Results: We invstigated the microbiota of the root endosphere and rhizosphere soils of the rice cultivar Nipponbare (NPB) and its Piz-t-transgenic line (NPB-Piz-t) when infected with the filamentous fungus Magnaporthe oryzae (M. oryzae) isolate KJ201, using 16S rRNA and internal transcribed spacer 1 (ITS1) amplicon sequencing. The rhizosphere soils showed higher bacterial and fungal richness and diversity than the endosphere except for fungal richness in the rhizosphere soils of the mock treatment. Bacteria richness and diversity increased in the endospheric communities of NPB and Piz-t under inoculation with KJ201 (referred to as 'NPB-KJ201' and 'Piz-t-KJ201', respectively) compared with the corresponding mock treatments, with the NPB-KJ201 showing the highest diversity in the four bacterial endocompartments. In contrast, fungal richness and diversity decreased in the endospheric communities of NPB-KJ201 and Piz-t-KJ201, relative to the corresponding mock treatments, with NPB-KJ201 and Piz-t-KJ201 having the lowest richness and diversity, respectively, across the four fungal endocompartments. Principal component analysis (PCA) indicated that the microbiota of Piz-t-KJ201 of root endophytes were mostly remarkablely distinct from that of NPB-KJ201. Co-occurrence network analysis revealed that the phyla Proteobacteria and Ascomycota were the key contributors to the bacterial and fungal communities, respectively. Furthermore, a comparative metabolic analysis showed that the contents of tryptophan metabolism and indole alkaloid biosynthesis were significantly lower in the Piz-t-KJ201 plants.

Conclusions: In this study, we compared the diversity, composition, and assembly of microbial communities associated with the rhizosphere soils and endosphere of Piz-t-KJ201 and NPB-KJ201. On the basis of the different compositions, diversities, and assemblies of the microbial communities among different compartments, we propose that the host genotype and inoculation pattern of M. oryzae played dominant roles in determining the microbial community assemblage. Further metabolomics analysis revealed that some metabolites may influence changes in bacterial communities. This study improves our understanding of the complex interactions between rice and M. oryzae, which could be useful in developing new strategies to improve rice resistance through the manipulation of soil microorganisms.
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http://dx.doi.org/10.1186/s12284-021-00486-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113375PMC
May 2021

Weighted Gene Co-Expression Network Coupled with a Critical-Time-Point Analysis during Pathogenesis for Predicting the Molecular Mechanism Underlying Blast Resistance in Rice.

Rice (N Y) 2020 Dec 11;13(1):81. Epub 2020 Dec 11.

Biotechnology Research Institute, Fujian Provincial Key Laboratory of Genetic Engineering for Agriculture, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.

Background: Rice blast, caused by the ascomycete fungus M. oryzae, is one of the most important diseases of rice. Although many blast resistance (R) genes have been identified and deployed in rice varieties, the molecular mechanisms responsible for the R gene-mediated defense responses are yet not fully understood.

Results: In this study, we used comparative transcriptomic analysis to explore the molecular mechanism involved in Piz-t-mediated resistance in a transgenic line containing Piz-t (NPB-Piz-t) compared to Nipponbare (NPB). Clustering and principal component analysis (PCA) revealed that the time-point at 24-h post inoculation (hpi) was the most important factor distinguishing the four time-points, which consisted of four genes of mitogen-activated protein kinases (MAPKs) signaling pathway, one gene related to WRKY DNA-binding domain containing protein, five pathogenesis-related protein (OsPR1s) genes, and three genes of R proteins involving in the most significant protein-protein interaction (PPI) pathway. Using weighted gene co-expression network analysis (WGCNA) to investigate RNA-seq data across 0, 24, 48, and 72 hpi, nine modules with similar patterns expression pattern (SEP) and three modules with differential expression pattern (DEP) between NPB-Piz-t and NPB across 0, 24, 48, and 72 hpi with KJ201 (referred to as Piz-t-KJ201 and NPB-KJ201) were identified. Among these the most representative SEP green-yellow module is associated with photosynthesis, and DEP pink module comprised of two specific expressed nucleotide-binding domain and leucine-rich repeat (NLR) genes of LOC_Os06g17900 and LOC_Os06g17920 of Pi2/9 homologous, three NLR genes of LOC_Os11g11810, LOC_Os11g11770, and LOC_Os11g11920 which are putatively associated with important agronomic traits, and a B3 DNA binding domain containing protein related genes (LOC_Os10g39190). Knockout of LOC_Os10g39190 via CRISPR-Cas9 resulted in plant death at the seedling stage.

Conclusions: The research suggested that Piz-t and multiple NLR network might play important roles in the regulation of the resistance response in the Piz-t-KJ201 interaction system. The identified genes provide an NLR repository to study the rice-M. oryzae interaction system and facilitate the breeding of blast-resistant cultivars in the future.
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http://dx.doi.org/10.1186/s12284-020-00439-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7732884PMC
December 2020

Loss function of SL (sekiguchi lesion) in the rice cultivar Minghui 86 leads to enhanced resistance to (hemi)biotrophic pathogens.

BMC Plant Biol 2020 Nov 4;20(1):507. Epub 2020 Nov 4.

State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.

Background: Serotonin, originally identified as a neurotransmitter in mammals, functions as an antioxidant to scavenge cellular ROS in plants. In rice, the conversion of tryptamine to serotonin is catalyzed by SL (sekiguchi lesion), a member of cytochrome P450 monooxygenase family. The sl mutant, originated from rice cultivar Sekiguchi-asahi, exhibits spontaneous lesions, whereas its immune responses to pathogens have not been clearly characterized.

Results: Here we identified three allelic mutants of SL in an indica rice restore line Minghui 86 (MH86), named as sl-MH-1, - 2 and - 3, all of which present the typical lesions under normal growth condition. Compared with those in MH86, the serotonin content in sl-MH-1 is dramatically decreased, whereas the levels of tryptamine and L-trytophan are significantly increased. The sl-MH-1 mutant accumulates high HO level at its lesion sites and is more sensitive to exogenous HO treatment than the wild type. When treated with the reductant vitamin C (Vc), the lesion formation on sl-MH-1 leaves could be efficiently suppressed. In addition, sl-MH-1 displayed more resistant to both the blast fungus and blight bacteria, Pyricularia oryzae (P. oryzae, teleomorph: Magnaporthe oryzae) and Xanthomonas oryzae pv. Oryzae (Xoo), respectively. The pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) responses, like reactive oxygen species (ROS) burst and callose deposition, were enhanced in sl-MH-1. Moreover, loss function of SL resulted in higher resting levels of the defense hormones, salicylic acid and jasmonic acid. The RNA-seq analysis indicated that after P. oryzae infection, transcription of the genes involved in reduction-oxidation regulation was the most markedly changed in sl-MH-1, compared with MH86.

Conclusions: Our results indicate that SL, involving in the final step of serotonin biosynthesis, negatively regulates rice resistance against (hemi)biotrophic pathogens via compromising the PTI responses and defense hormones accumulation.
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http://dx.doi.org/10.1186/s12870-020-02724-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7640399PMC
November 2020

AGAMOUS-LIKE67 Cooperates with the Histone Mark Reader EBS to Modulate Seed Germination under High Temperature.

Plant Physiol 2020 09 23;184(1):529-545. Epub 2020 Jun 23.

Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, 200444 Shanghai, China

Seed germination is a vital developmental process that is tightly controlled by environmental signals, ensuring germination under favorable conditions. High temperature (HT) suppresses seed germination. This process, known as thermoinhibition, is achieved by activating abscisic acid and inhibiting gibberellic acid biosynthesis. The zinc-finger protein SOMNUS (SOM) participates in thermoinhibition of seed germination by altering gibberellic acid/abscisic acid metabolism, but the underlying regulatory mechanism is poorly understood. In this study, we report that SOM binds to its own promoter and activates its own expression in Arabidopsis () and identify the MADS-box transcription factor AGAMOUS-LIKE67 (AGL67) as a critical player in SOM function, based on its ability to recognize CArG-boxes within the promoter and mediate the trans-activation of under HTs. In addition, AGL67 recruits the histone mark reader EARLY BOLTING IN SHORT DAY (EBS), which recognizes H3K4me3 at chromatin. In response to HTs, AGL67 and EBS are highly enriched around the promoter. The AGL67-EBS complex is also necessary for histone H4K5 acetylation, which activates expression, ultimately inhibiting seed germination. Taken together, our results reveal an essential mechanism in which AGL67 cooperates with the histone mark reader EBS, which bridges the process of H3K4me3 recognition with H4K5 acetylation, thereby epigenetically activating expression to suppress seed germination under HT stress.
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http://dx.doi.org/10.1104/pp.20.00056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7479893PMC
September 2020

Exploring the Distribution of Blast Resistance Alleles at the Locus in Major Rice-Producing Areas of China by a Novel Indel Marker.

Plant Dis 2020 Jul 20;104(7):1932-1938. Epub 2020 May 20.

State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.

Rice blast disease caused by the fungus damages cereal crops and poses a high risk to rice production around the world. Currently, planting cultivars with resistance () genes is still the most environment-friendly approach to control this disease. Effective identification of genes existing in diverse rice cultivars is important for understanding the distribution of genes and predicting their contribution to resistance against blast isolates in regional breeding. Here, we developed a new insertion/deletion (InDel) marker, Pigm/2/9InDel, that can differentiate the cloned genes (, , and /) at the locus. Pigm/2/9InDel combined with the marker Pi2-LRR for was applied to determine the distribution of these four genes among 905 rice varieties, most of which were collected from the major rice-producing regions in China. In brief, nine containing varieties from Fujian and Guangdong provinces were identified. All of the 62 -containing varieties were collected from Guangdong, and 60 varieties containing were from seven provinces. However, was not found in any of the Chinese varieties. The newly identified varieties carrying the alleles were further subjected to inoculation tests with regional blast isolates and field trials. Our results indicate that and alleles have been introgressed for blast resistance breeding mainly in the Fujian and Guangdong region, and is a valuable blast resistance resource to be introduced into China.
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http://dx.doi.org/10.1094/PDIS-10-19-2187-REDOI Listing
July 2020

Bulked Segregant Analysis Coupled with Whole-Genome Sequencing (BSA-Seq) Mapping Identifies a Novel Haplotype Conferring Basal Resistance to Rice Blast Disease.

Int J Mol Sci 2020 Mar 21;21(6). Epub 2020 Mar 21.

Marine and Agricultural Biotechnology Laboratory, Institute of Oceanography, Minjiang University, Fuzhou 350108, China.

Basal or partial resistance has been considered race-non-specific and broad-spectrum. Therefore, the identification of genes or quantitative trait loci (QTLs) conferring basal resistance and germplasm containing them is of significance in breeding crops with durable resistance. In this study, we performed a bulked segregant analysis coupled with whole-genome sequencing (BSA-seq) to identify QTLs controlling basal resistance to blast disease in an F population derived from two rice varieties, 02428 and LiXinGeng (LXG), which differ significantly in basal resistance to rice blast. Four candidate QTLs, , , , and , were mapped on chromosomes 4, 7, 8, and 11, respectively. Allelic and genotypic association analyses identified a novel haplotype of the durable blast resistance gene carrying double deletions of 30 bp and 33 bp in 02428 () as a candidate gene of . We further assessed haplotypes of in 325 rice accessions, and identified 11 haplotypes among the accessions, of which eight were novel types. While the resistant gene was found only in before, three Chinese varieties, ShuHui881, Yong4, and ZhengDa4Hao, were detected carrying the resistant allele. The allele and -containing rice germplasm, thus, provide valuable resources for breeding rice varieties, especially rice varieties, with durable resistance to blast disease. Our results also lay the foundation for further identification and functional characterization of the other three QTLs to better understand the molecular mechanisms underlying rice basal resistance to blast disease.
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http://dx.doi.org/10.3390/ijms21062162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7139700PMC
March 2020

Functional Identification of Novel Cell Death-inducing Effector Proteins from Magnaporthe oryzae.

Rice (N Y) 2019 Aug 6;12(1):59. Epub 2019 Aug 6.

Institute of Oceanography, Marine Biotechnology Center, Minjiang University, Fuzhou, 350108, China.

Background: Secreted effector proteins play critical roles in plant-fungal interactions. The Magnaporthe oryzae genome encodes a large number of secreted proteins. However, the function of majority of M. oryzae secreted proteins remain to be characterized. We previously identified 851 in planta-expressed M. oryzae genes encoding putative secreted proteins, and characterized five M. oryzae cell death-inducing proteins MoCDIP1 to MoCDIP5. In the present study, we expand our work on identification of novel MoCDIP proteins.

Results: We performed transient expression assay of 98 more in planta-expressed M. oryzae putative secreted protein genes, and identified eight novel proteins, MoCDIP6 to MoCDIP13, that induced plant cell death. Yeast secretion assay and truncation expression analysis revealed that the signal peptides that led the secretion of proteins to the extracellular space, were required for cell death inducing activity of the novel MoCDIPs except for MoCDIP8. Exogenous treatment of rice seedlings with recombinant MoCDIP6 or MoCDIP7 resulted in enhanced resistance to blast fungus, indicating that the two MoCDIPs trigger cell death and elicit defense responses in rice.

Conclusions: The newly identified MoCDIP6 to MoCDIP13, together with previously identified MoCDIP1 to MoCDIP5, provide valuable targets for further dissection of the molecular mechanisms underlying the rice-blast fungus interaction.
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http://dx.doi.org/10.1186/s12284-019-0312-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6684714PMC
August 2019

Proteomic analysis of the defense response to Magnaporthe oryzae in rice harboring the blast resistance gene Piz-t.

Rice (N Y) 2018 Aug 15;11(1):47. Epub 2018 Aug 15.

Biotechnology Research Institute, Fujian Key Laboratory of Genetic Engineering for Agriculture, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.

Background: Rice blast (caused by Magnaporthe oryzae) is one of the most destructive diseases of rice. While many blast resistance (R) genes have been identified and deployed in rice cultivars, little is known about the R gene-mediated defense mechanism. We used a rice transgenic line harboring the resistance gene Piz-t to investigate the R gene-mediated resistance response to infection.

Results: We conducted comparative proteome profiling of the Piz-t transgenic Nipponbare line (NPB-Piz-t) and wild-type Nipponbare (NPB) inoculated with M. oryzae at 24, 48, 72 h post-inoculation (hpi) using isobaric tags for relative and absolute quantification (iTRAQ) analysis. Comparative analysis of the response of NPB-Piz-t to the avirulent isolate KJ201 and the virulent isolate RB22 identified 114 differentially expressed proteins (DEPs) between KJ201-inoculated NPB-Piz-t (KJ201-Piz-t) and mock-treated NPB-Piz-t (Mock-Piz-t), and 118 DEPs between RB22-inoculated NPB-Piz-t (RB22-Piz-t) and Mock-Piz-t. Among the DEPs, 56 occurred commonly in comparisons KJ201-Piz-t/Mock-Piz-t and RB22-Piz-t/Mock-Piz-t. In a comparison of the responses of NPB and NPB-Piz-t to isolate KJ201, 93 DEPs between KJ201-Piz-t and KJ201-NPB were identified. DEPs in comparisons KJ201-Piz-t/Mock-Piz-t, RB22-Piz-t/Mock-Piz-t and KJ201-Piz-t/KJ201-NPB contained a number of proteins that may be involved in rice response to pathogens, including pathogenesis-related (PR) proteins, hormonal regulation-related proteins, defense and stress response-related proteins, receptor-like kinase, and cytochrome P450. Comparative analysis further identified 7 common DEPs between the comparisons KJ201-Piz-t/KJ201-NPB and KJ201-Piz-t/RB22-Piz-t, including alcohol dehydrogenase I, receptor-like protein kinase, endochitinase, similar to rubisco large subunit, NADP-dependent malic enzyme, and two hypothetical proteins.

Conclusions: Our results provide a valuable resource for discovery of complex protein networks involved in the resistance response of rice to blast fungus.
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http://dx.doi.org/10.1186/s12284-018-0240-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093832PMC
August 2018

Endosperm-specific OsPYL8 and OsPYL9 act as positive regulators of the ABA signaling pathway in rice seed germination.

Funct Plant Biol 2017 Jun;44(6):635-645

Biotechnology Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350003, China.

Pyrabactin resistance-like (PYL) proteins were identified as receptors of the plant hormone ABA. The PYL family consists of multiple members that are differently expressed in various tissues, exhibit distinct biochemical properties and have diverse biological functions. In the present study, we explored the expression patterns of the rice (Oryza sativa L.) OsPYL family genes and determined that OsPYL8 and OsPYL9 are specifically expressed in the endosperms. Sequence analysis and deletion experiments revealed that the OsPYL8 and OsPYL9 promoters contain multiple motifs involved in endosperm-specific expression. Transgenic rice plants overexpressing OsPYL8 or OsPYL9 showed hypersensitivity to ABA during seed germination, suggesting that both OsPYL8 and OsPYL9 act as positive regulators of the ABA signalling pathway in the seed. OsPYL8 and OsPYL9 interact with OsPP2C51 and OsPP2C68, whose expression is induced in the endosperms by ABA. Our results provided a foundation for future studies on OsPYL8- and OsPYL9-mediated ABA signalling in the rice endosperms.
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http://dx.doi.org/10.1071/FP16314DOI Listing
June 2017

Allele-specific marker-based assessment revealed that the rice blast resistance genes Pi2 and Pi9 have not been widely deployed in Chinese indica rice cultivars.

Rice (N Y) 2016 Dec 4;9(1):19. Epub 2016 May 4.

Biotechnology Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.

Background: The most sustainable approach to control rice blast disease is to develop durably resistant cultivars. In molecular breeding for rice blast resistance, markers developed based on polymorphisms between functional and non-functional alleles of resistance genes, can provide precise and accurate selection of resistant genotypes without the need for difficult, laborious and time-consuming phenotyping. The Pi2 and Pi9 genes confer broad-spectrum resistance against diverse blast isolates. Development of allele-specific markers for Pi2 and Pi9 would facilitate breeding of blast resistant rice by using the two blast resistance genes.

Result: In this work, we developed two new markers, named Pi9-Pro and Pi2-LRR respectively, targeting the unique polymorphisms of the resistant and susceptible alleles of Pi2 and of Pi9. The InDel marker Pi9-Pro differentiates three different genotypes corresponding to the Pi2/Piz-t, Pi9 and non-Pi2/Piz-t/Pi9 alleles, and the CAPS marker Pi2-LRR differentiates the Pi2 allele from the non-Pi2 allele. Based on the two newly developed markers and two available markers Pi2SNP and Pi9SNP, the presence of Pi2 and Pi9 was assessed in a set of 434 rice accessions consisting of 377 Chinese indica cultivars/breeding materials and 57 Chinese japonica cultivars/breeding materials. Of the 434 accessions tested, while one indica restorer line Huazhan was identified harboring the Pi2 resistance allele, no other rice line was identified harboring the Pi2 or Pi9 resistance alleles.

Conclusions: Allele-specific marker-based assessment revealed that Pi2 and Pi9 have not been widely incorporated into diverse Chinese indica rice cultivars. Thus, the two blast resistance genes can be new gene sources for developing blast resistant rice, especially indica rice, in China. The two newly developed markers should be highly useful for using Pi2 and Pi9 in marker-assisted selection (MAS) breeding programs.
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http://dx.doi.org/10.1186/s12284-016-0091-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4854853PMC
December 2016

The role of nitric oxide signalling in response to salt stress in Chlamydomonas reinhardtii.

Planta 2016 Sep 26;244(3):651-69. Epub 2016 Apr 26.

School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.

Main Conclusion: Nitric oxide signal and GSNOR activity play an essential role for Chlamydomonas reinhardtii response to salt stress. The unicellular alga Chlamydomonas reinhardtii is one of the most important model organisms phylogenetically situated between higher plants and animals. In the present study, we used comparative proteomics and physiological approaches to study the mechanisms underlying the response to salt stress in C. reinhardtii. We identified 74 proteins that accumulated differentially after salt stress, including oxidative enzymes and enzymes associated with nitric oxide (NO) metabolism, cell damage, and cell autophagy processes. A set of antioxidant enzymes, as well as S-nitrosoglutathione reductase (GSNOR) activity, were induced to balance the cellular redox status during short-term salt stress. Enzymes involved in DNA repair and cell autophagy also contribute to adaptation to short-term salt stress. However, under long-term salt stress, antioxidant enzymes and GSNOR were gradually inactivated through protein S-nitrosylation, leading to oxidative damage and a reduction in cell viability. Modulating the protein S-nitrosylation levels by suppressing GSNOR activity or adding thioredoxin affected the plant's adaptation to salt stress, through altering the redox status and DNA damage and autophagy levels. Based on these data, we propose that unicellular algae use multiple strategies to adapt to salt stress, and that, during this process, GSNOR activity and protein S-nitrosylation levels play important roles.
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http://dx.doi.org/10.1007/s00425-016-2528-0DOI Listing
September 2016

Comparative proteome analyses reveal that nitric oxide is an important signal molecule in the response of rice to aluminum toxicity.

J Proteome Res 2013 Mar 6;12(3):1316-30. Epub 2013 Feb 6.

School of Life Sciences, Jiangsu Key Laboratory for Eco-Agriculture Biotechnology around Hongze Lake, Huaiyin Normal University, Huai'an223300, China.

Acidic soils inhibit crop yield and reduce grain quality. One of the major contributing factors to acidic soil is the presence of soluble aluminum (Al(3+)) ions, but the mechanisms underlying plant responses to Al(3+) toxicity remain elusive. Nitric oxide (NO) is an important messenger and participates in various plant physiological responses. Here, we demonstrate that Al(3+) induced an increase of NO in rice seedlings; adding exogenous NO alleviated the Al(3+) toxicity related to rice growth and photosynthetic capacity, effects that could be reversed by suppressing NO metabolism. Comparative proteomic analyses successfully identified 92 proteins that showed differential expression after Al(3+) or NO treatment. In particular, some of the proteins are involved in reactive oxygen species (ROS) and reactive nitrogen species (RNS) metabolism. Further analyses confirmed that NO treatment reduced Al(3+)-induced ROS and RNS toxicities by increasing the activities and protein expression of antioxidant enzymes, as well as S-nitrosoglutathione reductase (GSNOR). Suppressing GSNOR enzymatic activity aggravated Al(3+) damage to rice and increased the accumulation of RNS. NO treatment altered the expression of proteins associated with cell wall synthesis, cell division and cell structure, calcium signaling and defense responses. On the basis of these results, we propose that NO activates multiple pathways that enhance rice adaptation to Al(3+) toxicity. Such findings may be applicable to crop engineering to enhance yield and improve stress tolerance.
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http://dx.doi.org/10.1021/pr300971nDOI Listing
March 2013

A high-density intervarietal map of the wheat genome enriched with markers derived from expressed sequence tags.

Theor Appl Genet 2008 Jul 24;117(2):181-9. Epub 2008 Apr 24.

The Applied Plant Genomics Laboratory, Crop Genomics and Bioinformatics Centre, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.

Bread wheat (Triticum aestivum L.) is a hexaploid species with a large and complex genome. A reference genetic marker map, namely the International Triticeae Mapping Initiative (ITMI) map, has been constructed with the recombinant inbred line population derived from a cross involving a synthetic line. But it is not sufficient for a full understanding of the wheat genome under artificial selection without comparing it with intervarietal maps. Using an intervarietal mapping population derived by crossing Nanda2419 and Wangshuibai, we constructed a high-density genetic map of wheat. The total map length was 4,223.1 cM, comprising 887 loci, 345 of which were detected by markers derived from expressed sequence tags (ESTs). Two-thirds of the high marker density blocks were present in interstitial and telomeric regions. The map covered, mostly with the EST-derived markers, approximately 158 cM of telomeric regions absent in the ITMI map. The regions of low marker density were largely conserved among cultivars and between homoeologous subgenomes. The loci showing skewed segregation displayed a clustered distribution along chromosomes and some of the segregation distortion regions (SDR) are conserved in different mapping populations. This map enriched with EST-derived markers is important for structure and function analysis of wheat genome as well as in wheat gene mapping, cloning, and breeding programs.
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http://dx.doi.org/10.1007/s00122-008-0764-9DOI Listing
July 2008

Molecular genetic analysis of five spike-related traits in wheat using RIL and immortalized F2 populations.

Mol Genet Genomics 2007 Jan 11;277(1):31-42. Epub 2006 Oct 11.

The Applied Plant Genomics Lab and National Key Lab of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.

Kernel number per spike is one of the most important yield components of wheat. To map QTLs related to kernel number including spike length (SPL), spikelet number per spike (SPN), fertile spikelet number (FSPN), sterile spikelet number (SSPN) and compactness, and to characterize the inheritance modes of the QTLs and two-locus interactions, 136 recombinant inbred lines (RILs) derived from 'Nanda2419' x 'Wangshuibai' and an immortalized F(2 )population (IF(2)) generated by randomly permutated intermating of these RILs were investigated. QTL mapping made use of the previously constructed over 3300 cM linkage map of the RIL population. Three, five, two, two and six chromosome regions were identified, respectively, for their association with SPL, SPN, FSPN, SSPN, and compactness in at least two of the three environments examined. All compactness QTLs but one shared the respective intervals of QSpn.nau-5A and the SPL QTLs. Xcfd46-Xwmc702 interval on chromosome 7D was related to all traits but SSPN and had consistently the largest effects. The fact that not all the compactness QTL intervals were related to both SPL and SPN indicates that compactness is regulated by different mechanisms. Interval coincidence between QTLs of SPL and SPN and between QTLs of FSPN and SSPN was minimal. For all the traits, favorable alleles exist in both parents. Inheritance modes from additiveness to overdominance of the QTLs were revealed and two-locus interactions were detected, implying that the traits studied are under complex genetic control. The results could contribute to wheat yield improvement and better use of Wangshuibai and Nanda2419 the two special germplasms in wheat breeding program.
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http://dx.doi.org/10.1007/s00438-006-0166-0DOI Listing
January 2007