Age-Dependent Growth-Related QTL Variations in Pacific Abalone, Haliotis discus hannai.

Pacific abalone is a high-value, commercially important marine invertebrate. It shows low growth as well as individual and yearly growth variation in aquaculture. Marker-assisted selection breeding could potentially resolve the problem of low and variable growth and increase genetic gain. Expression of quantitative trait loci (QTLs) for growth-related traits, viz., body weight, shell length, and shell width were analyzed at the first, second, and third year of age using an F1 cross population. A total of 37 chromosome-wide QTLs were identified in linkage groups 01, 02, 03, 04, 06, 07, 08, 10, 11, 12, and 13 at different ages. None of the QTLs detected at any one age were expressed in all three age groups. This result suggests that growth-related traits at different ages are influenced by different QTLs in each year. However, multiple-trait QTLs (where one QTL affects all three traits) were detected each year that are also age-specific. Eleven multiple-trait QTLs were detected at different ages: two QTLs in the first year; two QTLs in the second year; and seven QTLs in the third year. As abalone hatcheries use three-year-old abalone for breeding, QTL-linked markers that were detected at the third year of age could potentially be used in marker-assisted selection breeding programs.

Glucosinolates and Biotic Stress Tolerance in Brassicaceae with Emphasis on Cabbage: A Review.

Glucosinolates (GSLs) and GSL-associated genes are receiving increasing attention from molecular biologists due to their multifunctional properties. GSLs are secondary metabolites considered to be highly active in most Brassica species. Their importance has motivated the discovery and functional analysis of the GSLs and GSL hydrolysis products involved in disease development in brassicas and other plants. Comprehensive knowledge of the GSL content of Brassica species and the molecular details of GSL-related genes will help elucidate the molecular control of this plant defense system. This report provides an overview of the current status of knowledge on GSLs, GSL biosynthesis, as well as hydrolysis related genes, and GSL hydrolysis products that regulate fungal, bacterial, and insect resistance in cabbage and other brassicas.

Genotyping by Sequencing (GBS)-Based QTL Mapping for Bacterial Fruit Blotch (BFB) in Watermelon.

Watermelon (Citrullus lanatus), an economically important and nutritionally rich Cucurbitaceous crop grown worldwide, is severely affected by bacterial fruit blotch (BFB). Development of resistant cultivar is the most eco-friendly, cost-effective, and sustainable way to tackle this disease. This requires wider understanding of the genetics of resistance to BFB. In this study, we identified quantitative trait loci (QTLs) associated with BFB resistance in an F2 mapping population developed from BFB-resistant 'PI 189225' (Citrullus amarus) and -susceptible 'SW 26' (C. lanatus) genotypes based on the polymorphic markers identified by genotyping by sequencing (GSB). A linkage map covering a total genetic distance of 3377.1 cM was constructed. Two QTLs for BFB resistance, namely, ClBFB10.1 and ClBFB10.2, both located on chromosome 10 explaining 18.84 and 15.41% of the phenotypic variations, respectively, were identified. Two SNP-based high-resolution melting (HRM) markers WmBFB10.1 and WmBFB10.2 having high positive correlation with resistance vs. susceptible alleles were developed. The efficacy of the markers was validated in another F2 population derived from SW34 × PI 189225. The highest phenotypic variation was found in the locus ClBFB10.2, which also contains three putative candidate genes for resistance to BFB. These findings will accelerate the development of BFB-resistant watermelon varieties via molecular breeding.

Erratum: Development of diagnostic molecular markers for marker-assisted breeding against bacterial wilt in tomato.

[This corrects the article DOI: 10.1270/jsbbs.20027.].

QTL associated with Gummy Stem Blight (GSB) resistance in watermelon.

BACKGROUND: Gummy stem blight (GSB), caused by Didymella bryoniae (syn. Stagonosporopsis cucurbitacearum), produces devastating symptoms on whole plants of watermelon (Citrullus lanatus) and other cucurbits, significantly reducing yield and quality. Identification of genetic determinants and sources of resistance to this devastating GSB disease in watermelon is essential for developing resistant varieties. RESULTS: In this study, we aimed at identifying quantitative trait loci (QTLs) linked to GSB resistance in melon. We identified the genome-wide single nucleotide polymorphisms (SNPs) by genotyping by sequencing (GBS) of an F2 population developed from C. lanatus lines, 'PI 279461' (resistant) ✕ 'PI 223764' (susceptible). Inheritance analysis indicated that resistance to GSB is a multi-genic trait in this population. Three QTLs namely, ClGSB1.1, ClGSB10.1, and ClGSB11.1 associated with GSB resistance, explaining approximately 10% of the phenotypic variation, were identified. Among these, the QTL ClGSB1.1 on chromosome 1 is identified as a major QTL harboring five candidate genes associated with GSB resistance including two RLKs (ClC01G014900 and ClC01G015010), two WRKY transcription factors (ClC01G014910 and ClC01G014990), and one AvrRpt-cleavage domain protein (ClC01G015130). CONCLUSION: Two high resolution melting (HRM) markers, WmGSB1.1-2 and WmGSB1.1-7 having a high positive correlation with the phenotypic variations, were developed. Five potential candidate genes were predicted to be associated with GSB resistance. These findings will help breeders to develop watermelon cultivars resistant to GSB.

Interspecific and Intraspecific Hybrid Rootstocks to Improve Horticultural Traits and Soil-Borne Disease Resistance in Tomato.

Tomato rootstocks are important to increase yield and control soil-borne pathogens, increasing vigor for a longer crop cycle and tolerance to biotic and abiotic stress. This study, conducted in the greenhouse of Sunchon National University during the period from 2019 to 2022, aimed to identify local soil-borne-disease resistant interspecific and intraspecific tomato hybrid rootstocks. The 71 interspecific hybrids (S. lycopersicum × S. habrochaites) showed that the germination vigor (GV) was less than Maxifort, except for several combinations. The germination rate (GP) of cross-species hybrids showed a different pattern according to the hybrid combinations, of which three combinations showed less than 30%. The horticultural traits, such as GV and GP, of the intraspecies hybrid (S. l × S. l) combination were significantly improved compared to that of Maxifort. In 71 combinations (S. l × S. h) and 25 combinations (S. l × S. l), MAS was used to evaluate the resistance of eight genes related to soil-borne pathogens, four genes related to vector-mediated pathogens, and three genes related to air-borne pathogens. The results showed that the new hybrid combination had improved resistance over the commercial-stock Maxifort. Therefore, interspecies and intraspecies hybrid techniques for breeding commercial rootstocks can be utilized as a way to improve horticultural properties and resistance to soil-borne diseases in tomato.

Inheritance of Black Rot Resistance and Development of Molecular Marker Linked to Xcc Races 6 and 7 Resistance in Cabbage.

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), produces V-shaped chlorotic lesions on the leaves of cabbage (Brassica oleracea var. capitata L.), causing darkened veins and drastically reducing yield and quality. Of the 11 Xcc races identified, races 1, 4, and 6 are predominant globally. In the present study, we aimed to develop a molecular marker linked to black rot resistance against Xcc races 6 and 7. Crossed between black rot-resistant ('SCNU-C-3470') and -susceptible ('SCNU-C-3328') lines obtained 186 F2 plants. Resistance to Xcc race 6 segregated in a 3:1 (susceptible:resistant) ratio in the F2 population, which is consistent with a monogenic recessive trait. Nucleotide-binding site (NBS) leucine rich repeat (LRR)-encoding resistance (R) genes play a crucial role in plant defenses to various pathogens. The candidate R gene (Bol031422) located on chromosome C08, previously reported by our research group, was cloned and sequenced in resistant and susceptible cabbage lines. The R gene Bol031422 consisted of a single exon with a 3 bp insertion/deletions (InDels), a 292 bp polymorphism (an insertion in the exon of the resistant line relative to the susceptible line) and several single nucleotide polymorphisms (SNPs). Here, we developed the InDel marker BR6-InDel to assess linkage between variation at Bol031422 and resistance to Xcc races 6 and 7. This marker will help cabbage breeders develop cabbage cultivars resistant to Xcc races 6 and 7.

Development of PCR-Based Molecular Marker for Detection of Xanthomonas campestris pv. campestris Race 6, the Causative Agent of Black Rot of Brassicas.

Xanthomonas campestris pv. campestris (Xcc), the pathogen of black rot which is the most destructive disease of Brassica vegetables throughout the world. Here, we reported two novel sequence-characterized amplified region (SCAR) markers (i.e., XccR6-60 and XccR6-67) for the detection of Xcc race 6 via re-alignment of the complete genome sequences of Xcc races/strains/pathovars. The specificity of SCAR primer sets was verified by mean of PCR amplification using the genomic DNA template of Xcc races/strains/pathovars and two other plant infecting bacterial strains. The PCR result revealed that the XccR6-60 and XccR6-67 primer sets amplified 692-bp and 917-bp DNA fragments, respectively, specifically from race 6, while no visible amplification was detected in other samples. In addition, the SCAR primers were highly sensitive and can detect from a very low concentration of genomic DNA of Xcc race 6. However, the complete genome sequence of Xcc race 6 is not yet publicly available. Therefore, the cloning and sequencing of XccR6-60 and XccR6-67 fragments from race 6 provide more evidence of the specificity of these markers. These results indicated that the newly developed SCAR markers can successfully, effectively and rapidly detect Xcc race 6 from other Xcc races/strains/pathovars as well as other plant pathogenic bacteria. This is the first report for race-specific molecular markers for Xcc race 6.

Transcriptome wide SSR discovery cross-taxa transferability and development of marker database for studying genetic diversity population structure of Lilium species.

Lily belongs to family liliaceae, which mainly propagates vegetatively. Therefore, sufficient number of polymorphic, informative, and functional molecular markers are essential for studying a wide range of genetic parameters in Lilium species. We attempted to develop, characterize and design SSR (simple sequence repeat) markers using online genetic resources for analyzing genetic diversity and population structure of Lilium species. We found di-nucleotide repeat motif were more frequent (4684) within 0.14 gb (giga bases) transcriptome than other repeats, of which was two times higher than tetra-repeat motifs. Frequency of di-(AG/CT), tri-(AGG/CTT), tetra-(AAAT), penta-(AGAGG), and hexa-(AGAGGG) repeats was 34.9%, 7.0%, 0.4%, 0.3%, and 0.2%, respectively. A total of 3607 non-redundant SSR primer pairs was designed based on the sequences of CDS, 5'-UTR and 3'-UTR region covering 34%, 14%, 23%, respectively. Among them, a sub set of primers (245 SSR) was validated using polymerase chain reaction (PCR) amplification, of which 167 primers gave expected PCR amplicon and 101 primers showed polymorphism. Each locus contained 2 to 12 alleles on average 0.82 PIC (polymorphic information content) value. A total of 87 lily accessions was subjected to genetic diversity analysis using polymorphic SSRs and found to separate into seven groups with 0.73 to 0.79 heterozygosity. Our data on large scale SSR based genetic diversity and population structure analysis may help to accelerate the breeding programs of lily through utilizing different genomes, understanding genetics and characterizing germplasm with efficient manner.

Glucosinolate Profile and Glucosinolate Biosynthesis and Breakdown Gene Expression Manifested by Black Rot Disease Infection in Cabbage.

Cabbage (Brassica oleracea var. capitata) is an economically important crop in the family Brassicaceae. Black rot disease is a top ranked cabbage disease, which is caused by Xanthomonas campestris pv. campestris (Xcc) and may reduce 50% crop loss. Therefore, we need a clear understanding of black rot disease resistance for sustainable disease management. The secondary metabolites, like Glucosinolate (GSL) presents in Brassica species, which plays a potential role in the defense mechanism against pathogens. However, there is little known about GSL-regulated resistance mechanisms and GSL biosynthesis and the breakdown related gene expression after black rot disease infection in cabbage. In this study, relative expression of 43 biosynthetic and breakdown related GSLs were estimated in the black rot resistant and susceptible cabbage lines after Xcc inoculation. Ten different types of GSL from both aliphatic and indolic groups were identified in the contrasting cabbage lines by HPLC analysis, which included six aliphatic and four indolic compounds. In the resistant line, nine genes (MYB122-Bol026204, MYB34-Bol017062, AOP2-Bo9g006240, ST5c-Bol030757, CYP81F1-Bol017376, CYP81F2-Bol012237, CYP81F4-Bol032712, CYP81F4-Bol032714 and PEN2-Bol030092) showed consistent expression patterns. Pearson's correlation coefficient showed positive and significant association between aliphatic GSL compounds and expression values of ST5c-Bol030757 and AOP2-Bo9g006240 genes as well as between indolic GSL compounds and the expression of MYB34-Bol017062, MYB122-Bol026204, CYP81F2-Bol012237, CYP81F4-Bol032712 and CYP81F4-Bol032714 genes. This study helps in understanding the role of GSL biosynthesis and breakdown related genes for resistance against black rot pathogen in cabbage, which could be further confirmed through functional characterization either by overexpression or knock-out mutation.

Characterization of Insulin-Like Growth Factor Binding Protein 7 (Igfbp7) and Its Potential Involvement in Shell Formation and Metamorphosis of Pacific Abalone, Haliotis discus hannai.

Insulin-like growth factor binding proteins (IGFBPs) are secreted proteins that play an important role in IGF regulation of growth and development of vertebrate and invertebrates. In this study, the IGFBP7 gene was cloned and characterized from mantle tissues of H. discus hannai, and designated as Hdh IGFBP7. The full-length cDNA sequence transcribed from the Hdh IGFBP7 gene was 1519-bp long with an open reading frame of 720-bp corresponding to a putative polypeptide of 239 amino acids. The molecular mass of its mature protein was approximately 23.44 KDa with an estimated isoelectric point (pI) of 5.35, and it shared significant homology with IGFBP7 gene of H. madaka. Hdh IGFBP7 has a characteristic IGFBP N-terminal domain (22-89 aa), a kazal-type serine proteinase inhibitor domain (77-128), and an immunoglobulin-like C2 domain (144-223). Furthermore, twelve cysteine residues and a signature motif of IGFBPs (XCGCCXXC) were found in its N-terminal domain. Phylogenetic analysis revealed that Hdh IGFBP7 was aligned with IGFBP7 of H. madaka. Tissue distribution analysis showed that the mRNA of Hdh IGFBP7 was expressed in all examined tissues, with the highest expression level observed in the mantle and gill tissues. The expression level of Hdh IGFBP7 mRNA was relatively higher at the juvenile stage during its metamorphosis period. In situ hybridization showed that Hdh IGFBP7 transcript was expressed in epithelial cells of the dorsal mantle pallial and mucus cells of the branchial epithelium in gill. These results provide basic information for future studies on the role of IGFBP7 in IGF regulation of shell growth, development and metamorphosis of abalone.

Development of diagnostic molecular markers for marker-assisted breeding against bacterial wilt in tomato.

Bacterial wilt, caused by the Ralstonia pseudosolanacearum species complex, is an important vascular disease that limits tomato production in tropical and subtropical regions. Two major quantitative trait loci (QTL) of bacterial wilt resistance on chromosome 6 (Bwr-6) and 12 (Bwr-12) were previously identified in Solanum lycopersicum 'Hawaii 7996'; however, marker-assisted breeding for bacterial wilt resistance is not well established. To dissect the QTL, six cleaved amplified polymorphic sites (CAPS) and derived CAPS (dCAPS) markers within the Bwr-6 region and one dCAPS marker near Bwr-12 were developed, and resistance levels in 117 tomato cultivars were evaluated. Two markers, RsR6-5 on chromosome 6 and RsR12-1 on chromosome 12, were selected based on the genotypic and phenotypic analysis. The combination of RsR6-5 and RsR12-1 effectively distinguishes resistant and susceptible cultivars. Furthermore, the efficiency of the two markers was validated in the F3 generation derived from the F2 population between E6203 (susceptible) and Hawaii 7998 (resistant). Resistant alleles at both loci led to the resistance to bacterial wilt. These markers will facilitate marker-assisted breeding of tomato resistant to bacterial wilt.

Knockout of SlMS10 Gene (Solyc02g079810) Encoding bHLH Transcription Factor Using CRISPR/Cas9 System Confers Male Sterility Phenotype in Tomato.

The utilization of male sterility into hybrid seed production reduces its cost and ensures high purity of tomato varieties because it does not produce pollen and has exserted stigmas. Here, we report on the generation of gene edited lines into male sterility phenotype by knockout of SlMS10 gene (Solyc02g079810) encoding the bHLH transcription factor that regulates meiosis and cell death of the tapetum during microsporogenesis in the tomato. Twenty-eight gene edited lines out of 60 transgenic plants were selected. Of these, eleven different mutation types at the target site of the SlMS10 gene were selected through deep sequencing analysis. These mutations were confirmed to be transmitted to subsequent generations. The null lines without the transferred DNA (T-DNA) were obtained by segregation in the T1 and T2 generations. In addition, we showed that the cr-ms10-1-4 mutant line exhibited dysfunctional meiosis and abnormal tapetum during flower development, resulting in no pollen production. RT-PCR analysis showed that the most genes associated with pollen and tapetum development in tomatoes had lower expression in the cr-ms10-1-4 mutant line compared to wild type. We demonstrate that modification of the SlMS10 gene via CRISPR/Cas9-mediated genome editing results in male sterility of tomato plants. Our results suggest an alternative approach to generating male sterility in crops.

ddRAD-seq derived genome-wide SNPs, high density linkage map and QTLs for fruit quality traits in strawberry (Fragaria x ananassa).

Understanding the genetic determinants are essential for improving the fruit quality traits of strawberry. In this study, we focused on mapping the loci for fruit-length (FL), -diameter (FD), -weight (FW) and -soluble solid content (SSC) using the genome-wide single nucleotide polymorphisms (SNPs) identified via ddRAD-sequencing of the F1 population raised from Maehyang (♀) X Festival (♂). A total of 12,698 high quality SNPs were identified of which 1554 SNPs that showed significant Mendelian segregation (p < 0.05) were mapped to 53 linkage groups (LG) spanning a total of 2937.93 cM with an average marker density of 2.14 cM/locus. Six QTLs for FL and four QTLs for each of FD, FW and SSC were identified that explained 24-35%, 21-42%, 24-54% and 23-50% of overall phenotypic variations, respectively. The genes that lie within these QTL regions were extracted and discussed thoroughly. In addition, a high resolution melting marker (MF154) were designed based on the SNP A1723G of the UDP-glucose 4-epimerase GEPI48-like gene FAN_iscf00021287. The marker detected the high vs low sugar containing F1 plants and commercial cultivars with 81.39% and 86.95% detection accuracy, respectively. These SNPs, linkage map, QTLs and candidate genes will be helpful in understanding and improving the fruit quality traits of strawberry.

Glucosinolate profile and Myrosinase gene expression are modulated upon Plasmodiophora brassicae infection in cabbage.

Clubroot is a devastating disease of Brassicaceae caused by the biotrophic protist Plasmodiophora brassicae. The progression of clubroot disease is modulated by the glucosinolate (GSL) profile of the host plant. GSL is hydrolysed by the enzyme myrosinase upon cell disruption and gives rise to metabolites like isothiocyanate, nitriles, thiocyanates, epithionitriles and oxazolidines. Some of these metabolites play important roles in the plant's defence mechanism. We identified 13 Myrosinase (Myro) and 28 Myrosinase-Binding Protein-like (MBP) genes from Brassica oleracea L. using a comparative genomics approach and characterised them through in silico analyses. We compared the expression patterns of these genes in a clubroot-susceptible line and a resistant line following inoculation with P. brassicae. Two BolMyro and 12 BolMBP genes were highly expressed in the susceptible line, whereas only one BolMyro and five BolMBP genes were highly expressed in the resistant line. Principal component analysis confirmed that specific GSL profiles and gene expression were modulated due to pathogen infection. Plants with higher levels of neoglucobrassicin, glucobrassicin and methooxyglucobrassicin produced disease symptoms and formed galls, whereas, plants with higher levels of sinigrin, hydroxyglucobrassicin and progoitrin produced less symptoms with almost no galls. Our results provide insights into the roles of Myro and MBP genes in GSL hydrolysis during P. brassicae infection, which will help for developing clubroot resistant cabbage lines.

Expression and Role of Biosynthetic, Transporter, Receptor, and Responsive Genes for Auxin Signaling during Clubroot Disease Development.

Auxins play a pivotal role in clubroot development caused by the obligate biotroph Plasmodiophora brassicae. In this study, we investigated the pattern of expression of 23 genes related to auxin biosynthesis, reception, and transport in Chinese cabbage (Brassica rapa) after inoculation with P. brassicae. The predicted proteins identified, based on the 23 selected auxin-related genes, were from protein kinase, receptor kinase, auxin responsive, auxin efflux carrier, transcriptional regulator, and the auxin-repressed protein family. These proteins differed in amino acids residue, molecular weights, isoelectric points, chromosomal location, and subcellular localization. Leaf and root tissues showed dynamic and organ-specific variation in expression of auxin-related genes. The BrGH3.3 gene, involved in auxin signaling, exhibited 84.4-fold increase in expression in root tissues compared to leaf tissues as an average of all samples. This gene accounted for 4.8-, 2.6-, and 5.1-fold higher expression at 3, 14, and 28 days post inoculation (dpi) in the inoculated root tissues compared to mock-treated roots. BrNIT1, an auxin signaling gene, and BrPIN1, an auxin transporter, were remarkably induced during both cortex infection at 14 dpi and gall formation at 28 dpi. BrDCK1, an auxin receptor, was upregulated during cortex infection at 14 dpi. The BrLAX1 gene, associated with root hair development, was induced at 1 dpi in infected roots, indicating its importance in primary infection. More interestingly, a significantly higher expression of BrARP1, an auxin-repressed gene, at both the primary and secondary phases of infection indicated a dynamic response of the host plant towards its resistance against P. brassicae. The results of this study improve our current understanding of the role of auxin-related genes in clubroot disease development.

Leptosphaeria maculans Alters Glucosinolate Accumulation and Expression of Aliphatic and Indolic Glucosinolate Biosynthesis Genes in Blackleg Disease-Resistant and -Susceptible Cabbage Lines at the Seedling Stage.

The fungal pathogen, Leptosphaeria maculans causes a severe and economically important disease to Brassica crops globally, well-known as blackleg. Besides, the anti-oxidative defense response of glucosinolates to fungal pathogens is widely established. Despite notable importance of glucosinolates in blackleg disease resistance the association of glucosinolate pathway genes in glucosinolate mediated defense response after L. maculans infection remains incompletely understood. The current study was designed to identify glucosinolate-biosynthesis specific genes among the eight selected candidates induced by L. maculans and associated alterations in glucosinolate profiles to explore their roles in blackleg resistance at the seedling stage of cabbage plants. The defense responses of four cabbage inbred lines, two resistant and two susceptible, were investigated using two L. maculans isolates, 03-02s and 00-100s. Pathogen-induced glucosinolate accumulation dynamically changed from two days after inoculation to four days after inoculation. In general, glucosinolate biosynthetic genes were induced at 24 h after inoculation and glucosinolate accumulation enhanced at two days after inoculation. An increase in either aliphatic (GIB, GRA) or indolic (GBS and MGBS) glucosinolates was associated with seedling resistance of cabbage. Pearson correlation showed the enhanced accumulation of MGBS, GBS, GIB, GIV and GRA after the inoculation of fungal isolates was associated with expression of specific genes. Principal component analysis separated two resistant cabbage lines-BN4098 and BN4303 from two susceptible cabbage lines-BN4059 and BN4072 for variable coefficients of disease scores, glucosinolate accumulation and expression levels of genes. Enhanced MGBS content against both fungal isolates, contributing to seedling resistance in two interactions-BN4098 × 03-02s and BN4303 × 00-100s and enhanced GBS content only in BN4098 × 03-02s interaction. Aliphatic GRA took part in resistance of BN4098 × 00-100s interaction whereas aliphatic GIB took part is resistance of BN4098 × 03-02s interaction. Aliphatic GIV accumulated upon BN4098 × 03-02s interaction but GSL-OH-Bol033373 and CYP81F2-Bol026044 showed enhanced expression in BN4303 × 03-02s interaction. The association between the selected candidate genes, corresponding glucosinolates, and seedling resistance broaden the horizon of glucosinolate conciliated defense against L. maculans in cabbage seedlings.

Characterization, identification and expression profiling of genome-wide R-genes in melon and their putative roles in bacterial fruit blotch resistance.

BACKGROUND: Bacterial fruit blotch (BFB), a disease caused by Acidovorax citrulli, results in significant economic losses in melon. The causal QTLs and genes for resistance to this disease have yet to be identified. Resistance (R)-genes play vital roles in resistance to plant diseases. Since the complete genome sequence of melon is available and genome-wide identification of R-genes has been performed for this important crop, comprehensive expression profiling may lead to the identification of putative candidate genes that function in the response to BFB. RESULTS: We identified melon accessions that are resistant and susceptible to BFB through repeated bioassays and characterized all 70 R-genes in melon, including their gene structures, chromosomal locations, domain organizations, motif distributions, and syntenic relationships. Several disease resistance-related domains were identified, including NBS, TIR, LRR, CC, RLK, and DUF domains, and the genes were categorized based on the domains of their encoded proteins. In addition, we profiled the expression patterns of the genes in melon accessions with contrasting levels of BFB resistance at 12 h, 1 d, 3 d, and 6 d after inoculation with A. citrulli. Six R-genes exhibited consistent expression patterns (MELO3C023441, MELO3C016529, MELO3C022157, MELO3C022146, MELO3C025518, and MELO3C004303), with higher expression levels in the resistant vs. susceptible accession. CONCLUSION: We identified six putative candidate R-genes against BFB in melon. Upon functional validation, these genes could be targeted for manipulation via breeding and biotechnological approaches to improve BFB resistance in melon in the future.

Transcriptome Analysis by RNA-Seq Reveals Genes Related to Plant Height in Two Sets of Parent-hybrid Combinations in Easter lily (Lilium longiflorum).

In this study, two different hybrids of Easter lily (Lilium longiflorum), obtained from two cross combinations, along with their four parents were sequenced by high-throughput RNA-sequencing (RNA-Seq) to find out differentially expressed gene in parent-hybrid combinations. The leaf mRNA profiles of two hybrids and their four parents were RNA-sequenced with a view to identify the potential candidate genes related to plant height heterosis. In both cross combinations, based to morphological traits mid-parent heterosis (MPH) was higher than high-parent heterosis (HPH) for plant height, leaf length, and number of flowers whereas HPH was higher than MPH for flowering time. A total of 4,327 differentially expressed genes (DEGs) were identified through RNA-Seq between the hybrids and their parents based on fold changes (FC) ≥ 2 for up- and ≤ -2 for down-regulation. Venn diagram analysis revealed that there were 703 common DEGs in two hybrid combinations, those were either up- or down-regulated. Most of the commonly expressed DEGs exhibited higher non-additive effects especially overdominance (75.9%) rather than additive (19.4%) and dominance (4.76%) effects. Among the 384 functionally annotated DEGs identified through Blast2GO tool, 12 DEGs were up-regulated and 16 of them were down-regulated in a similar fashion in both hybrids as revealed by heat map analysis. These 28 universally expressed DEGs were found to encode different types of proteins and enzymes those might regulate heterosis by modulating growth, development and stress-related functions in lily. In addition, gene ontology (GO) analysis of 260 annotated DEGs revealed that biological process might play dominant role in heterotic expression. In this first report of transcriptome sequencing in Easter lily, the notable universally up-regulated DEGs annotated ABC transporter A family member-like, B3 domain-containing, disease resistance RPP13/1, auxin-responsive SAUR68-like, and vicilin-like antimicrobial peptides 2-2 proteins those were perhaps associated with plant height heterosis. The genes expressed universally due to their overdominace function perhaps influenced MPH for greater plant height- largely by modulating biological processes involved therein. The genes identified in this study might be exploited in heterosis breeding for plant height of L. longiflorum.

Expression and Role of Response Regulating, Biosynthetic and Degrading Genes for Cytokinin Signaling during Clubroot Disease Development.

The obligate biotroph Plasmodiophora brassicae causes clubroot disease in oilseeds and vegetables of the Brassicaceae family, and cytokinins play a vital role in clubroot formation. In this study, we examined the expression patterns of 17 cytokinin-related genes involved in the biosynthesis, signaling, and degradation in Chinese cabbage inoculated with the Korean pathotype group 4 isolate of P. brassicae, Seosan. This isolate produced the most severe clubroot symptoms in Chinese cabbage cultivar "Bullam-3-ho" compared to three other Korean geographical isolates investigated. BrIPT1, a cytokinin biosynthesis gene, was induced on Day 1 and Day 28 in infected root tissues and the upregulation of this biosynthetic gene coincided with the higher expression of the response regulators BrRR1, on both Days and BrRR6 on Day 1 and 3. BrRR3 and 4 genes were also induced during gall enlargement on Day 35 in leaf tissues. The BrRR4 gene, which positively interact with phytochrome B, was consistently induced in leaf tissues on Day 1, 3, and 14 in the inoculated plants. The cytokinin degrading gene BrCKX3-6 were induced on Day 14, before gall initiation. BrCKX2,3,6 were induced until Day 28 and their expression was downregulated on Day 35. This insight improves our current understanding of the role of cytokinin signaling genes in clubroot disease development.