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The brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive pest of rice (Oryza sativa L.). Utilizing resistant rice cultivars that harbor resistance gene/s is an effective strategy for integrated pest management. Due to the co-evolution of BPH and rice, a single resistance gene may fail because of changes in the virulent BPH population. Thus, it is urgent to explore and map novel BPH resistance genes in rice germplasm. Previously, an indica landrace from India, Paedai kalibungga (PK), demonstrated high resistance to BPH in both in Wuhan and Fuzhou, China. To map BPH resistance genes from PK, a BC1F2:3 population derived from crosses of PK and a susceptible parent, Zhenshan 97 (ZS97), was developed and evaluated for BPH resistance. A novel BPH resistance locus, BPH39, was mapped on the short arm of rice chromosome 6 using next-generation sequencing-based bulked segregant analysis (BSA-seq). BPH39 was validated using flanking markers within the locus. Furthermore, near-isogenic lines carrying BPH39 (NIL-BPH39) were developed in the ZS97 background. NIL-BPH39 exhibited the physiological mechanisms of antibiosis and preference toward BPH. BPH39 was finally delimited to an interval of 84 Kb ranging from 1.07 to 1.15 Mb. Six candidate genes were identified in this region. Two of them (LOC_Os06g02930 and LOC_Os06g03030) encode proteins with a similar short consensus repeat (SCR) domain, which displayed many variations leading to amino acid substitutions and showed higher expression levels in NIL-BPH39. Thus, these two genes are considered reliable candidate genes for BPH39. Additionally, transcriptome sequencing, DEGs analysis, and gene RT-qPCR verification preliminary revealed that BPH39 may be involved in the jasmonic acid (JA) signaling pathway, thus mediating the molecular mechanism of BPH resistance. This work will facilitate map-based cloning and marker-assisted selection for the locus in breeding programs targeting BPH resistance. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-024-01485-6.
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BACKGROUND: The Glucan synthase-like (GSL) genes are indispensable for some important highly-specialized developmental and cellular processes involving callose synthesis and deposition in plants. At present, the best-characterized reproductive functions of GSL genes are those for pollen formation and ovary expansion, but their role in seed initiation remains unknown. RESULTS: We identified a rice seed mutant, watery seed 1-1 (ws1-1), which contained a mutation in the OsGSL2 gene. The mutant produced seeds lacking embryo and endosperm but filled with transparent and sucrose-rich liquid. In a ws1-1 spikelet, the ovule development was normal, but the microsporogenesis and male gametophyte development were compromised, resulting in the reduction of fertile pollen. After fertilization, while the seed coat normally developed, the embryo failed to differentiate normally. In addition, the divided endosperm-free nuclei did not migrate to the periphery of the embryo sac but aggregated so that their proliferation and cellularization were arrested. Moreover, the degeneration of nucellus cells was delayed in ws1-1. OsGSL2 is highly expressed in reproductive organs and developing seeds. Disrupting OsGSL2 reduced callose deposition on the outer walls of the microspores and impaired the formation of the annular callose sheath in developing caryopsis, leading to pollen defect and seed abortion. CONCLUSIONS: Our findings revealed that OsGSL2 is essential for rice fertility and is required for embryo differentiation and endosperm-free nucleus positioning, indicating a distinct role of OsGSL2, a callose synthase gene, in seed initiation, which provides new insight into the regulation of seed development in cereals.
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Cooking-caused rice grain expansion (CCRGE) is a critical trait for evaluating the cooking quality of rice. Previous quantitative trait locus (QTL) mapping studies on CCRGE have been limited to bi-parental populations, which restrict the exploration of natural variation and mapping resolution. To comprehensively and precisely dissect the genetic basis of CCRGE, we performed a genome-wide association study (GWAS) on three related indices: grain breadth expansion index (GBEI), grain length expansion index (GLEI), and grain length-breadth ratio expansion index (GREI), using 345 rice accessions grown in two years (environments) and 193,582 SNP markers. By analyzing each environment separately using seven different methods (3VmrMLM, mrMLM, FASTmrMLM, FASTmrEMMA, pLARmEB, pKWmEB, ISIS EM-BLASSO), we identified a total of 32, 19 and 27 reliable quantitative trait nucleotides (QTNs) associated with GBEI, GLEI and GREI, respectively. Furthermore, by jointly analyzing the two environments using 3VmrMLM, we discovered 19, 22 and 25 QTNs, as well as 9, 5 and 7 QTN-by-environment interaction (QEIs) associated with GBEI, GLEI and GREI, respectively. Notably, 12, 9 and 15 QTNs for GBEI, GLEI and GREI were found within the intervals of previously reported QTLs. In the vicinity of these QTNs or QEIs, based on analyses of mutation type, gene ontology classification, haplotype, and expression pattern, we identified five candidate genes that are related to starch synthesis and endosperm development. The five candidate genes, namely, LOC_Os04g53310 (OsSSIIIb, near QTN qGREI-4.5s), LOC_Os05g02070 (OsMT2b, near QTN qGLEI-5.1s), LOC_Os06g04200 (wx, near QEI qGBEI-6.1i and QTNs qGREI-6.1s and qGLEI-6.1t), LOC_Os06g12450 (OsSSIIa, near QTN qGLEI-6.2t), and LOC_Os08g09230 (OsSSIIIa, near QTN qGBEI-8.1t), are predicted to be involved in the process of rice grain starch synthesis and to influence grain expansion after cooking. Our findings provide valuable insights and will facilitate genetic research and improvement of CCRGE.
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Crop reproductive development is vulnerable to heat stress, and the genetic modulation of thermotolerance during the reproductive phase, especially the early stage, remains poorly understood. We isolated a Poaceae-specific FAR-RED ELONGATED HYPOCOTYLS3 (FHY3)/FAR-RED IMPAIRED RESPONSE1 (FAR1)family transcription factor, Thermo-sensitive Spikelet Defects 1 (TSD1), derived from transposase in rice (Oryza sativa) TSD1 was highly expressed in spikelets, induced by heat, and specifically enhanced the thermotolerance of spikelet morphogenesis. Disrupting TSD1 did not affect vegetative growth but markedly retarded spikelet initiation and development, as well as caused varying degrees of spikelet degeneration, depending on the temperature. Most tsd1 spikelets were normal at low temperature but gradually degenerated as temperature increased, and all disappeared at high temperature, leading to naked branches. TSD1 directly promoted the transcription of YABBY1 and YABBY3 and could physically interact with YABBY1 and three TOB proteins, YABBY5, YABBY4, and YABBY3. These YABBY proteins can form either homodimers or heterodimers and play an important role in spikelet morphogenesis, similar to TSD1. Notably, the knockout mutant yab5-ko and double mutant tsd1 yab5-ko resembled tsd1 in spikelet appearance and response to temperature, indicating that these genes likely participate in spikelet development through the cooperative TSD1-YABBY module. These findings reveal a distinctive function of FHY3/FAR1 family genes and a unique TSD1-YABBY complex to acclimate spikelet development to high temperature in rice, providing insight into the regulating pathway of enhancing thermotolerance in plant reproductive development.
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Oryza , Temperatura , Temperatura Alta , Temperatura Baixa , Reprodução , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
High-density genetic maps can significantly improve the resolution of QTL mapping. We constructed a high-density recombination bin-based genetic map of eggplant based on 200 F2 plants from an interspecific cross (Solanum melongena × S. incanum) using the whole genome resequencing strategy. The map was 2022.8 cM long, covering near 99% of the eggplant genome. The map contained 3776 bins, with 3644 (96.5%) being effective (position non-redundant) ones, giving a nominal average distance of 0.54 cM and an effective average distance of 0.56 cM between adjacent bins, respectively. Using this map and 172 F2:3 lines, a major QTL with pleiotropic effects on two anthocyanin pigmentation-related traits, leaf vein color (LVC) and fruit pericarp color (FPC), was steadily detected in a bin interval of 2.28 cM (or 1.68 Mb) on chromosome E10 in two cropping seasons, explaining ~65% and 55% of the phenotypic variation in LVC and FPC, respectively. Genome-wide association analysis in this population validated the QTL and demonstrated the correctness of mapping two bins of chromosome E02 onto E10. Bioinformatics analysis suggested that a WDR protein gene inside the bin interval with reliable effective variation between the two parents could be a possible candidate gene of the QTL.
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Solanum melongena , Antocianinas/genética , Antocianinas/metabolismo , Estudo de Associação Genômica Ampla , Pigmentação/genética , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Recombinação Genética/genética , Solanum melongena/genética , Solanum melongena/metabolismoRESUMO
The heterosis in hybrid rice is highly affected by the environment and hybrid weakness occurs frequently depending on the genotypes of the hybrid and its parents. Hybrid weakness was also observed in our field experiments on nine rice hybrids produced by 3 × 3 incomplete diallel crosses. Among the nine hybrids, five displayed mid-parent heterosis (MPH) for grain yield per plant, while four showed mid-parent hybrid weakness (MPHW). A sequencing analysis of transcriptomes in panicles at the seed-filling stage revealed a significant association between enhanced non-additive gene expression (NAE) and allele-specific gene expression (ASE) with hybrid weakness. High proportions of ASE genes, with most being of mono-allele expression, were detected in the four MPHW hybrids, ranging from 22.65% to 45.97%; whereas only 4.80% to 5.69% of ASE genes were found in the five MPH hybrids. Moreover, an independence test indicated that the enhancements of NAE and ASE in the MPHW hybrids were significantly correlated. Based on the results of our study, we speculated that an unfavorable environment might cause hybrid weakness by enhancing ASE and NAE at the transcriptome level.
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The evening complex (EC) plays a critical role in photoperiod flowering in Arabidopsis. Nevertheless, the underlying functions of individual components and coordinate regulation mechanism of EC genes in rice flowering remain to be elucidated. Here, we characterized the critical role of LUX ARRHYTHMO (LUX) in photoperiod perception and coordinating vegetative growth and flowering in rice. Non-functional alleles of OsLUX extremely extended vegetative phase, leading to photoperiod-insensitive late flowering and great increase of grain yield. OsLUX displayed an obvious diurnal rhythm expression with the peak at dusk and promoted rice flowering via coordinating the expression of genes associated with the circadian clock and the output integrators of photoperiodic flowering. OsLUX combined with OsELF4a and OsELF3a or OsELF3b to form two ECs, of which the OsLUX-OsELF3a-OsELF4a was likely the dominant promoter for photoperiodic flowering. In addition, OsELF4a was also essential for promoting rice flowering. Unlike OsLUX, loss OsELF4a displayed a marginal influence under short-day (SD) condition, but markedly delayed flowering time under long-day (LD) condition. These results suggest that rice EC genes share the function of promoting flowering. This is agreement with the orthologs of SD plant, but opposite to the counterparts of LD species. Taken together, rice EC genes display similar but not identical function in photoperiodic flowering, probably through regulating gene expression cooperative and independent. These findings facilitate our understanding of photoperiodic flowering in plants, especially the SD crops.
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Deep sequencing-based bulked segregant analysis (BSA-seq) has become a popular approach for quantitative trait loci (QTL) mapping in recent years. Effective statistical methods for BSA-seq have been developed, but how to design a suitable experiment for BSA-seq remains unclear. In this paper, we show in theory how the major experimental factors (including population size, pool proportion, pool balance, and generation) and the intrinsic factors of a QTL (including heritability and degree of dominance) affect the power of QTL detection and the precision of QTL mapping in BSA-seq. Increasing population size can improve the power and precision, depending on the QTL heritability. The best proportion of each pool in the population is around 0.25. So, 0.25 is generally applicable in BSA-seq. Small pool proportion can greatly reduce the power and precision. Imbalance of pool pair in size also causes decrease of the power and precision. Additive effect is more important than dominance effect for QTL mapping. Increasing the generation of filial population produced by selfing can significantly increase the power and precision, especially from F2 to F3. These findings enable researchers to optimize the experimental design for BSA-seq. A web-based program named BSA-seq Design Tool is available at http://124.71.74.135/BSA-seqDesignTool/ and https://github.com/huanglikun/BSA-seqDesignTool.
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Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Mapeamento Cromossômico/métodosRESUMO
Bacterial leaf streak (BLS) is a devastating rice disease caused by the bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), which can result in severe damage to rice production worldwide. Based on a total of 510 rice accessions, trialed in two seasons and using six different multi-locus GWAS methods (mrMLM, ISIS EM-BLASSO, pLARmEB, FASTmrMLM, FASTmrEMMA and pKWmEB), 79 quantitative trait nucleotides (QTNs) reflecting 69 QTLs for BLS resistance were identified (LOD > 3). The QTNs were distributed on all chromosomes, with the most distributed on chromosome 11, followed by chromosomes 1 and 5. Each QTN had an additive effect of 0.20 (cm) and explained, on average, 2.44% of the phenotypic variance, varying from 0.00-0.92 (cm) and from 0.00-9.86%, respectively. Twenty-five QTNs were detected by at least two methods. Among them, qnBLS11.17 was detected by as many as five methods. Most of the QTNs showed a significant interaction with their environment, but no QTNs were detected in both seasons. By defining the QTL range for each QTN according to the LD half-decay distance, a total of 848 candidate genes were found for nine top QTNs. Among them, more than 10% were annotated to be related to biotic stress resistance, and five showed a significant response to Xoc infection. Our results could facilitate the in-depth study and marker-assisted improvement of rice resistance to BLS.
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Barley awns are highly active in photosynthesis and account for 30-50% of grain weight in barley. They are diverse in length, ranging from long to awnless, and in shape from straight to hooded or crooked. Their diversity and importance have intrigued geneticists for several decades. A large collection of awnness mutants are available-over a dozen of them have been mapped on chromosomes and a few recently cloned. Different awnness genes interact with each other to produce diverse awn phenotypes. With the availability of the sequenced barley genome and application of new mapping and gene cloning strategies, it will now be possible to identify and clone more awnness genes. A better understanding of the genetic basis of awn diversity will greatly facilitate development of new barley cultivars with improved yield, adaptability and sustainability.
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Mapeamento Cromossômico/métodos , Genes de Plantas , Hordeum/genética , Estruturas Vegetais/genética , Cromossomos de Plantas , Clonagem Molecular , Epistasia Genética , Variação Genética , Hordeum/anatomia & histologiaRESUMO
Awns are extending structures from lemmas in grasses and are very active in photosynthesis, contributing directly to the filling of the developing grain. Barley (Hordeum vulgare L.) awns are highly diverse in shape and length and are known to be controlled by multiple awn-related genes. The genetic effects of these genes on awn diversity and development in barley are multiplexed and include complementary effect, cumulative effect, duplicate effect, recessive epistasis, dominant epistasis, and inhibiting effect, each giving a unique modified Mendelian ratio of segregation. The complexity of gene interactions contributes to the awn diversity in barley. Excessive gene interactions create a challenging task for genetic mapping and specific strategies have to be developed for mapping genes with specific interactive effects. Awn gene interactions can occur at different levels of gene expression, from the transcription factor-mediated gene transcription to the regulation of enzymes and metabolic pathways. A better understanding of gene interactions will greatly facilitate deciphering the genetic mechanisms underlying barley awn diversity and development.
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Hordeum/crescimento & desenvolvimento , Locos de Características Quantitativas , Mapeamento Cromossômico , Epistasia Genética , Regulação da Expressão Gênica de Plantas , Hordeum/genética , Redes e Vias Metabólicas , Proteínas de Plantas/genéticaRESUMO
Genomic imprinting is an epigenetic phenomenon, which plays important roles in the growth and development of animals and plants. Immortalized F2 (imF2) populations generated by random cross between recombinant inbred (RI) or doubled haploid (DH) lines have been proved to have significant advantages for mapping imprinted quantitative trait loci (iQTLs), and statistical methods for this purpose have been proposed. In this paper, we propose a special type of imF2 population (R-imF2) for iQTL mapping, which is developed by random reciprocal cross between RI/DH lines. We also propose two modified iQTL mapping methods: two-step point mapping (PM-2) and two-step composite point mapping (CPM-2). Simulation studies indicated that: (i) R-imF2 cannot improve the results of iQTL mapping, but the experimental design can probably reduce the workload of population construction; (ii) PM-2 can increase the precision of estimating the position and effects of a single iQTL; and (iii) CPM-2 can precisely map not only iQTLs, but also non-imprinted QTLs. The modified experimental design and statistical methods will facilitate and promote the study of iQTL mapping.
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Class III peroxidases (PRXs) are plant-specific enzymes and play important roles in plant growth, development and stress response. In this study, a total of 102 non-redundant PRX gene members (StPRXs) were identified in potato (Solanum tuberosum L.). They were divided into 9 subfamilies based on phylogenetic analysis. The members of each subfamily were found to contain similar organizations of the exon/intron structures and protein motifs. The StPRX genes were not equally distributed among chromosomes. There were 57 gene pairs of segmental duplication and 26 gene pairs of tandem duplication. Expression pattern analysis based on the RNA-seq data of potato from public databases indicated that StPRX genes were expressed differently in various tissues and responded specifically to heat, salt and drought stresses. Most of the StPRX genes were expressed at significantly higher levels in root than in other tissues. In addition, real-time quantitative PCR (qRT-PCR) analysis for 7 selected StPRX genes indicated that these genes displayed various expression levels under abiotic stresses. Our results provide valuable information for better understanding the evolution of StPRX gene family in potato and lay the vital foundation for further exploration of PRX gene function in plants.
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Bacterial leaf steak (BLS) caused by Xanthomonas oryzae pv. oryzicola (Xoc) is a devastating disease in rice production. The resistance to BLS in rice is a quantitatively inherited trait, of which the molecular mechanism is still unclear. It has been proved that xa5, a recessive bacterial blast resistance gene, is the most possible candidate gene of the QTL qBlsr5a for BLS resistance. To study the molecular mechanism of xa5 function in BLS resistance, we created transgenic lines with RNAi of Xa5 (LOC_Os05g01710) and used RNA-seq to analyze the transcriptomes of a Xa5-RNAi line and the wild-type line at 9 h after inoculation with Xoc, with the mock inoculation as control. We found that Xa5-RNAi could (1) increase the resistance to BLS as expected from xa5; (2) alter (mainly up-regulate) the expression of hundreds of genes, most of which were related to disease resistance; and (3) greatly enhance the response of thousands of genes to Xoc infection, especially of the genes involved in cell death pathways. The results suggest that xa5 is the cause of BLS-resistance of QTL qBlsr5a and it displays BLS resistance effect probably mainly because of the enhanced response of the cell death-related genes to Xoc infection.
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Perfilação da Expressão Gênica/métodos , Oryza/genética , Oryza/microbiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/microbiologia , Xanthomonas/patogenicidade , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Interferência de RNA , Análise de Sequência de RNARESUMO
With fast-evolving next-generation sequencing technology, a great amount of plant genome and transcriptome data are becoming available. Due to the availability of mature microRNA (miRNA) sequence information from the miRBase (release 21) database, it is possible to predict endogenous target mimics (eTMs) in plant by searching seed-matched target sites. We identified a total of 2669 non-redundant eTM records in 43 plant species to create a specialized web-based database platform. The platform is named PendoTMBase, which can provide details of the eTMs. Predicted pairing structure between eTMs and their target miRNA, expression levels of eTMs pairs and associated GO annotations are also stored in the database. With evaluations performed in silico, we have found that the eTMs are representative and fit for genetic studies and high value-added plants breeding. The platform also provides a function of predicting novel eTMs based on the miRNA sequences submitted by users.
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Plantas , Genoma de Planta , Sequenciamento de Nucleotídeos em Larga Escala , MicroRNAs , Plantas/genética , TranscriptomaRESUMO
Barley (Hordeum vulgare) awns contribute to grain yield, but the genetic basis of awn development remains largely unclear. Five barley lines differing in awn traits and row types were used to create four F2 populations. Genetic analyses revealed that four pairs of genes were involved in awn development: A/a (awnless/awned), B/b (awnless/awned), H/h (hooded/straight), and L/l (long/short). Of these four loci, A, H and L functioned on both central rows (CR) and lateral rows (LR) of the barley spikes, while B exhibited effect only on LR. A and B had duplicate effects on LR, and both showed dominant epistasis to loci H and L, whereas H was epistatic to L. Meanwhile, A and B were found to be genetically linked, with a row-type locus V located between them. The genetic distances of A-V and B-V were estimated to be 9.6 and 7.7 cM, respectively. Literature search suggested that A, H and V may correspond to the reported Lks1, Kap1 and Vrs1, respectively, whereas B is a novel gene specifically controlling awn development on LR, designated as Lsa1 for lateral spikelet awnless 1. The only barley homolog of wheat awn inhibitor gene B1, HORVU2Hr1G077570, is a potential candidate of Lsa1.
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Variação Genética , Hordeum/anatomia & histologia , Hordeum/genética , Estruturas Vegetais/genética , Locos de Características Quantitativas/genética , Mapeamento Cromossômico , Cruzamentos Genéticos , Ligação Genética , Padrões de Herança/genética , Modelos Genéticos , FenótipoRESUMO
As a broad-spectrum disease resistance factor, MLO is involved in a variety of biotic and abiotic stress responses in plants. To figure out the structural features, phylogenetic relationships, and expression patterns of MLO genes, we investigated the genome and transcriptome sequencing data of 28 plant species using bioinformatics tools. A total of 197 MLO genes were identified. They possessed 5-7 transmembrane domains, but only partially contained a calmodulin-binding domain. A total of 359 polymorphic sites and 142 haplotypes were found in 143 sequences, indicating the rich nucleotide diversity of MLO genes. The MLO genes were unevenly distributed on chromosomes or scaffolds and were mainly located at the ends, forming clusters (24.1% genes), tandem duplicates (5.7%), and segment duplicates (36.2%). The MLO genes could be classified into three groups by phylogenetic analysis. The angiosperm genes were mainly in subgroup IA, Selaginella moellendorffii genes were in subgroup IA and IIIB, Physcomitrella patens genes were in subgroup IB and IIIA, and almost all algae genes were in group II. About half of the MLO genes had homologs within and across species. The Ka/Ks values were all less than 1, varying 0.01-0.78, suggesting that purifying selection had occurred in MLO gene evolution. In tomato, RNA-seq data indicated that SlMLO genes were highly expressed in roots, followed by flowers, buds, and leaves, and also regulated by different biotic stresses. qRT-PCR analysis revealed that SlMLO genes could respond to tomato bacterial wilt, with SlMLO1, SlMLO2, SlMLO4, and SlMLO6 probably involved in the susceptibility response, whereas SlMLO14 and SlMLO16 being the opposite. These results lay a foundation for the isolation and application of related genes in plant disease resistance breeding.
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Proteínas de Ligação a Calmodulina/genética , Resistência à Doença/genética , Ralstonia solanacearum/genética , Solanum lycopersicum/genética , Transcrição Gênica/genética , Proteínas de Arabidopsis/genética , Genoma de Planta/genética , Solanum lycopersicum/microbiologia , Magnoliopsida/genética , Filogenia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Ralstonia solanacearum/patogenicidade , Estresse Fisiológico/genética , Transcriptoma/genéticaRESUMO
Paw San Hmwe (PSH) is a high-quality rice cultivar from Myanmar. PSH has short and broad grains, but the grains become slender after cooking. This desirable feature can be described as a high value of grain length-breadth relative expansion index (GREI). To understand the genetic basis of high GREI in PSH, we crossed PSH with Guang 8B (G8B), a rice cultivar from China with low GREI, to develop an F2 population and a subsequent F2:3 population. Based on the phenotypes of these two populations measured in two years and using the method of sequencing-based bulked segregant analysis followed by verification with conventional linkage-based QTL mapping method, we mapped three QTLs for GREI. The three QTLs were located on chromosomes 3, 5 and 12, respectively, with the trait-increasing alleles all from PSH, and could explain a total of 62.5% of the phenotypic variance and 84.1% of the additive genetic variance. The results suggest that the three QTLs would be useful for the genetic improvement of GREI in rice, and the linked markers will facilitate the selection of the favorable alleles from PSH in breeding.
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Nested association mapping (NAM) has been an invaluable approach for plant genetics community and can dissect the genetic architecture of complex traits. As the most popular NAM analysis strategy, joint multifamily mapping can combine all information from diverse genetic backgrounds and increase population size. However, it is influenced by the genetic heterogeneity of quantitative trait locus (QTL) across various subpopulations. Multi-locus association mapping has been proven to be powerful in many cases of QTL mapping and genome-wide association studies. Therefore, we developed a multi-locus association model of multiple families in the NAM population, which could discriminate the effects of QTLs in all subpopulations. A series of simulations with a real maize NAM genomic data were implemented. The results demonstrated that the new method improves the statistical power in QTL detection and the accuracy in QTL effect estimation. The new approach, along with single-family linkage mapping, was used to identify QTLs for three flowering time traits in the maize NAM population. As a result, most QTLs detected in single family linkage mapping were identified by the new method. In addition, the new method also mapped some new QTLs with small effects, although their functions need to be identified in the future.
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MOTIVATION: Bulked segregant analysis by deep sequencing (BSA-seq) has been widely used for quantitative trait locus (QTL) mapping in recent years. A number of different statistical methods for BSA-seq have been proposed. However, determination of significance threshold, the key point for QTL identification, remains to be a problem that has not been well solved due to the difficulty of multiple testing correction. In addition, estimation of the confidence interval is also a problem to be solved. RESULTS: In this paper, we propose a new statistical method for BSA-seq, named Block Regression Mapping (BRM). BRM is robust to sequencing noise and is applicable to the case of low sequencing depth. Significance threshold can be reasonably determined by taking multiple testing correction into account. Meanwhile, the confidence interval of QTL position can also be estimated. AVAILABILITY AND IMPLEMENTATION: The R scripts of our method are open source under GPLv3 license at https://github.com/huanglikun/BRM. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.