Cucumber (Cucumis sativus L.) is a globally important vegetable crop. Ideal plant architecture optimizes spatial utilization, enhances economic coefficient, and facilitates mechanized cultivation. In this study, we identified a dwarf mutant, csdw3, exhibiting reduced plant height, shortened internodes, and fewer internodes. Genetic analysis showed that this dwarf phenotype is controlled by a single recessive gene. Fine-mapping localized the causal locus to an 80 kb region on chromosome 1, where we discovered a 102 bp deletion in CsCLV2, a gene encoding a leucine-rich repeat receptor-like protein homologous to Arabidopsis CLAVATA2. CRISPR-Cas9-generated loss-of-function mutants recapitulated the dwarf phenotype, confirming the role of CsCLV2 in plant height regulation. Histological examination revealed that CsCLV2 disruption causes premature termination of shoot apical meristem (SAM) development, reducing both internode number and length. Protein interaction assays further demonstrated that CsCLV2 associates with receptor-like kinase CsCIK1 (CLAVATA3 INSENSITIVE RECEPTOR KINASES 1), indicating their cooperative function in the CLV-WUS signaling pathway to maintain meristem activity. Our findings uncover a regulator of plant height in cucumber and provide valuable genetic resources for breeding ideotypes optimized for yield and cultivation efficiency.

Maize is a critical crop for food, feed, and bioenergy worldwide. This study characterized the genetic diversity and population structure of 212 important inbred lines collected from the Southeast China breeding program using the Maize6H-60K single nucleotide polymorphism (SNP) array. To investigate the genetic architecture of plant height (PH) and ear height (EH), genome-wide association analysis (GWAS) was performed on this population in 2021 and 2022. Cluster analysis and population genetic structure analysis grouped the 212 maize inbred lines into 10 distinct categories. GWAS identified significant associations for PH, EH, and the EH/PH ratio. A total of 40 significant SNP (p < 8.55359 × 10−7) were detected, including nine associated with PH, with phenotypic variation explained (PVE) ranging from 3.42% to 25.92%. Additionally, 16 SNP were linked to EH, with PVE ranging from 2.49% to 38.49%, and 15 SNP were associated with the EH/PH ratio, showing PVE between 3.43% and 16.83%. Five stable SNP, identified across two or more environments, were further analyzed. Three of these SNP loci are reported for the first time in this study: two loci associated with the PH, AX-108020973, and AX-108022922, as well as one new locus, AX-108096437, which was significantly associated with the EH/PH ratio. Additionally, two other significant SNP (AX-247241325 and AX-108097244) were located within a 2 Mb range of previously identified QTL and/or related SNP. Within the 200 kb confidence intervals of these five stable SNP loci, 76 functionally annotated genes were identified. Further functional analysis indicated that 14 of these genes may play a role in regulating plant morphology, which is primarily involved in hormone synthesis, microtubule development, root growth, and cell division regulation. For instance, the homologous genes GRMZM2G375249 and GRMZM2G076029 in maize correspond to OsPEX1 in rice, a protein similar to extension proteins that are implicated in lignin biosynthesis, plant growth promotion, and the negative regulation of root growth through gibberellin-mediated pathways. The candidate gene corresponding to AX-108097244 is GRMZM2G464754; previous studies have reported its involvement in regulating EH in maize. These findings enhance the understanding of QTL associated with maize plant-type traits and provide a foundation for cloning PH, EH-related genes. Therefore, the results also support the development of functional markers for target genes and the breeding of improved maize varieties.

Cucumber (Cucumis sativus L.) is a globally significant economic crop vulnerable to a multitude of diseases. Its two relatives, C. sativus var. hardwickii and C. hystrix, possess strong disease resistances and are valuable for cucumber resistance breeding. Nucleotide binding site leucine-rich repeat (NLR) genes are crucial in regulating resistance against phytopathogens and insects. However, their characteristics and resistance mechanisms in cucumber and its wild relatives remain poorly understood. Therefore, we conducted a comprehensive genomewide analysis of the NLR gene families in cucumber, C. sativus var. hardwickii, and C. hystrix using bioinformatics tools. A total of 63, 67, and 89 NLR genes were identified in the three genomes and were categorized into N, NL, TNL, CNL, and RNL classes. More than 50 % of the NLRs contained only 1-3 exons, and most cis-acting regulatory elements in the NLR gene promoters were disease resistance related- and phytohormone-responsive. Cucumber had a closer synteny relationship with C. sativus var. hardwickii than with C. hystrix, and unique motifs were found in C. hystrix NLR proteins. Moreover, the expression patterns of the NLR genes in cucumber and C. hystrix demonstrated specific transciptional responses and genotype/tissue-dependent expression variations under biotic and abiotic stresses, suggesting distinct defense adaptation strategies. Additionally, this study revealed the diversity and molecular phylogenetic relationships of 830 NLR genes in 14 cucurbit species. Overall, these findings advance our understanding of plant defense mechanisms and broaden the NLR gene pool that could be utilized in cucumber resistance breeding.

Bottle gourd(Lagenaria siceraria(Molina)Standl)is a widely distributed Cucurbitaceae species,but gaps and low-quality assemblies have limited its genomic study.To address this,we assembled a nearly complete,high-quality genome of the bottle gourd(Pugua)using PacBio HiFi sequencing and Hi-C correction.The genome,being 298.67 Mb long with a ContigN50 of 28.55 Mb,was identified to possess 11 chromosomes,11 centromeres,18 telomeres,and 24439 predicted protein-coding genes;notably,gap-free telomere-to-telomere assembly was accomplished for seven chromosomes.Based on the Pugua genome,the transcriptomic and metabolomic combined analyses revealed that amino acids and lipids accumulate during the expansion stage,while sugars and terpenoids increase during ripening.GA4 and genes of the Aux/IAA family mediate fruit expansion and maturation,while cell wall remodeling is regulated by factors such as XTHs,EXPs,polyphenols,and alkaloids,contributing to environmental adaptation.GGAT2 was positively correlated with glutamate,a source of umami,and SUS5 and SPS4 expression aligned with sucrose accumulation.This study provides a valuable genetic resource for bottle gourd research,enhancing the understanding of Cucurbitaceae evolution and supporting further studies on bottle gourd development,quality,and genetic improvement.

Seed reserve mobilization is a crucial physiological process during seed germination. Enhancing the reserve mobilization in sweet corn is vital for seed germination and seedling growth. In this study, a genome-wide association analysis (GWAS) was conducted to predict candidate genes for regulating the weight of mobilized reserved seeds (WMRS) and kernel weight (KW) in sweet corn. GWAS was performed using the BLINK model with the maize 56K SNP chip. The results indicated that there was a positive correlation between the WMRS and KW, with coefficients of variation of 68.18% and 44.63%. Association analysis identified thirteen SNPs associated with two traits, and linkage disequilibrium analysis revealed that eight of these SNPs were in strong linkage. A total of 298 candidate genes were identified within the confidence interval, of which 79 were annotated. About 20 candidate genes were identified through the comparison of homologous genes in Arabidopsis. These genes were enriched in regulating ribosome biogenesis, signal transduction, hormone synthesis, and RNA degradation processes. This study provides important insights into the genetic mechanisms governing germination traits in sweet corn, aiding further research into the localization and cloning of genes involved in the mobilization of reserve materials.

Soybean (Glycine max) is a vital food crop, serving as a major source of high-quality protein for human and animal consumption. Stem diameter is one of the primary determinants of the stem lodging resistance of a given plant, but there has been relatively little research to date focused on genes associated with this trait. To address this gap in the literature, 207 chromosome segment substitution lines (CSSLs) were generated in the present study through the crossing and backcrossing of the improved Suinong14 and the wild ZYD00006 soybean varieties. These CSSLs were then used for the mapping of quantitative trait loci (QTLs) associated with stem diameter in two-year field planting materials, leading to the identification of nine QTLs. Whole genome resequencing, RNA-seq, and qPCR were then used to evaluate candidate genes associated with stem diameter within these QTL intervals, ultimately leading to the selection of Glyma.04G004100 as a stem diameter-related gene. Subsequent qPCR analyses revealed that Glyma.04g004100 was upregulated in soybean plants with larger stem diameters, and haplotype analyses yielded results consistent with these stem diameter data in the population used to conduct this study. In summary, a series of QTLs associated with stem diameter were identified in the present study, resulting in the establishment of Glyma.04g004100 as a stem diameter-related gene. Together, these results offer a theoretical foundation for the future molecular-assisted breeding of lodging-resistant soybean varieties, and future functional research focused on Glyma.04g004100 may elucidate the molecular mechanisms and key signaling networks involved in soybean stem development.

Heat stress, as a negative factor, severely threatens the quality and production of bottle gourd, which prefers to grow in a warm environment. To understand which genes are involved in the resistance to heat stress in bottle gourd (Lagenaria siceraria (Mol.) Standl.), we analyzed the characteristics of two genetic bottle gourd varieties, “Mei feng”-MF (heat resistant) and “Lv long”-LL (heat sensitive). Under heat stress, MF plants exhibited a higher survival rate, lower relative electrolytic leakage, and decreased stomatal aperture compared with LL. In addition, RNA-Seq was carried out on the two varieties under normal conditions and heat stress. The results revealed a total of 1485 up-regulated and 946 down-regulated genes under normal conditions, while 602 genes were up-regulated and 1212 genes were down-regulated under heat stress. Among these genes, several differentially expressed genes (DEGs) involved in the MAPK (mitogen-activated protein kinase) signaling pathway and members of bHLH (basic helix-loop-helix) transcription factors showed significant up- or down-regulation after heat stress. Next, to validate these findings, we conducted quantitative real-time PCR (qRT-PCR) analysis, which confirmed the expression patterns of the genes detected through RNA-Seq. Collectively, the DEGs between the two contrasting cultivars identified in our study provide novel insight into excavating helpful candidate genes associated with heat tolerance in bottle gourd.

Soybean (Glycine max) is an economically important cash crop and food source that serves as a key source of high-quality plant-derived protein and oil. Seed vigor is an important trait that influences the growth and development of soybean plants in an agricultural setting, underscoring a need for research focused on identifying seed vigor-related genetic loci and candidate genes. In this study, a population consisting of 207 chromosome segment substitution lines (CSSLs) derived from the crossing and continuous backcrossing of the Suinong14 (improved cultivar, recurrent parent) and ZYD00006 (wild soybean, donor parent) soybean varieties was leveraged to identify quantitative trait loci (QTLs) related to seed vigor. The candidate genes detected using this approach were then validated through RNA-seq, whole-genome resequencing, and qPCR approaches, while the relationship between specific haplotypes and seed vigor was evaluated through haplotype analyses of candidate genes. Phenotypic characterization revealed that the seed vigor of Suinong14 was superior to that of ZYD00006, and 20 total QTLs were identified using the selected CSSLs. Glyma.03G256700 was also established as a seed vigor-related gene that was upregulated in high-vigor seeds during germination, with haplotypes for this candidate gene also remaining consistent with observed soybean seed vigor. The QTLs identified herein can serve as a foundation for future marker-assisted and convergent breeding efforts aimed at improving seed vigor. In addition, future molecular and functional research focused on Glyma.03G256700 has the potential to elucidate the signaling network and key regulatory mechanisms that govern seed germination in soybean plants.

Cucumber (Cucumis sativus L.) is cultivated worldwide and is known to be photophilic and thermophilic. Low light stress (LLS) in winter and spring in Northern and early spring in Southern China has a severe impact on the growth and development of greenhouse cucumbers. However, the molecular regulatory mechanisms of LLS in cucumbers remain unclear, which seriously limits the development of cucumber breeding under LLS. In this study, we investigated hypocotyl differences in two cucumber lines grown under LLS and normal (CK) condition. Under LLS, the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and malondialdehyde (MDA) declined tovarying degrees compared with CK, and Y8 showed a relatively small decline. The hypocotyl length of the F2 population is a quantitative trait controlled by multiple genes under LLS conditions. The candidate region for hypocotyl elongation under LLS was mapped to chromosome 2 using bulk segregant analysis sequencing (BSA-seq). In addition, transcriptome analysis revealed 2786 differentially expressed genes (DEGs), of which 871 DEGs were specifically identified between Y5 and Y8 under LLS. Among these DEGs, 12 DEGs were involved in plant hormone signal transduction. Association analysis of the BSA-Seq and RNA-Seq results suggested that 36 DEGs were as candidate genes. Furthermore, three TFs (NAC, MYB and C2H2) may be considered the most likely candidate genes of hypocotyl elongation under LLS. Our results provide comprehensive understandings of the mechanism of hypocotyl elongation under LLS, and contribute to foundation for cloning the genes involved in hypocotyl elongation under LLS.

Rapeseed is a significant global source of plant oil. Silique size, particularly silique length (SL), impacts rapeseed yield. SL is a typical quantitative trait controlled by multiple genes. In our previous study, we constructed a DH population of 178 families known as the 158A-SGDH population. In this study, through SL QTL mapping, we identified twenty-six QTL for SL across five replicates in two environments. A QTL meta-analysis revealed eight consensus QTL, including two major QTL: cqSL.A02-1 (11.32–16.44

Soybean (Glycine max) plants first emerged in China, and they have since been established as an economically important oil crop and a major source of daily protein for individuals throughout the world. Seed emergence height is the first factor that ensures seedling adaptability to field management practices, and it is closely related to epicotyl length. In the present study, the Suinong 14 and ZYD00006 soybean lines were used as parents to construct chromosome segment substitution lines (CSSLs) for quantitative trait loci (QTL) identification. Seven QTLs were identified using two years of epicotyl length measurement data. The insertion region of the ZYD00006 fragment was identified through whole genome resequencing, with candidate gene screening and validation being performed through RNA-Seq and qPCR, and Glyma.08G142400 was ultimately selected as an epicotyl length-related gene. Through combined analyses of phenotypic data from the study population, Glyma.08G142400 expression was found to be elevated in those varieties exhibiting longer epicotyl length. Haplotype data analyses revealed that epicotyl data were consistent with haplotype typing. In summary, the QTLs found to be associated with the epicotyl length identified herein provide a valuable foundation for future molecular marker-assisted breeding efforts aimed at improving soybean emergence height in the field, with the Glyma.08G142400 gene serving as a regulator of epicotyl length, offering new insight into the mechanisms that govern epicotyl development.

Cucumber is one of the most important vegetable crops, which is widely planted all over the world. Cucumber always suffers from high-temperature stress in South China in summer. In this study, liquid chromatography–mass spectrometry (LC-MS) analysis was used to study the differential metabolites of cucumber anther between high-temperature (HT) stress and normal condition (CK). After HT, the pollen fertility was significantly reduced, and abnormal anther structures were observed by the paraffin section. In addition, the metabolomics analysis results showed that a total of 125 differential metabolites were identified after HT, consisting of 99 significantly upregulated and 26 significantly downregulated metabolites. Among these differential metabolites, a total of 26 related metabolic pathways were found, and four pathways showed significant differences, namely, porphyrin and chlorophyll metabolism; plant hormone signal transduction; amino sugar and nucleotide sugar metabolism; and glycine, serine, and threonine metabolism. In addition, pollen fertility was decreased by altering the metabolites of plant hormone signal transduction and amino acid and sugar metabolism pathway under HT. These results provide a comprehensive understanding of the metabolic changes in cucumber anther under HT.

Photosynthesis, a fundamental process for plant growth and development, is dependent on chloroplast formation and chlorophyll synthesis. Severe disruption of chloroplast structure results in albinism of higher plants. In the present study, we report a cucumber albino alc mutant that presented white cotyledons under normal light conditions and was unable to produce first true leaf. Meanwhile, alc mutant could grow creamy green cotyledons under dim light conditions but died after exposure to normal light irradiation. No chlorophyll and carotenoid were detected in the alc mutant grown under normal light conditions. Using transmission electron microscopy, impaired chloroplasts were observed in this mutant. The genetic analysis indicated that the albino phenotype was recessively controlled by a single locus. Comparative transcriptomic analysis between the alc mutant and wild type revealed that genes involved in chlorophyll metabolism and the methylerythritol 4-phosphate pathway were affected in the alc mutant. In addition, three genes involved in chloroplast development, including two FtsH genes and one PPR gene, were found to have negligible expression in this mutant. The quality of RNA sequencing results was further confirmed by real-time quantitative PCR analysis. We also examined 12 homologous genes from alc mutant in other plant species, but no genetic variation in the coding sequences of these genes was found between alc mutant and wild type. Taken together, we characterized a cucumber albino mutant with albinism phenotype caused by chloroplast development deficiency and this mutant can pave way for future studies on plastid development.

Cucumber (Cucumis sativus L.) is an important vegetable crop, which is thermophilic not heat resistant. High-temperature stress always results in sterility at reproductive stage. In the present study, we evaluate the male flower developmental changes under normal (CK) and heat stress (HS) condition. After HS, the activities of peroxidase (POD) and superoxide dismutase (SOD) and the contents of malondialdehyde (MDA) were increased. In addition, the pollen fertility was significantly decreased; and abnormal tapetum and microspore were observed by paraffin section. Transcriptome analysis results presented that total of 5828 differentially expressed genes (DEGs) were identified after HS. Among these DEGs, 20 DEGs were found at four stages, including DNA binding transcription factor, glycosyltransferase, and wound-responsive family protein. The gene ontology term of carbohydrate metabolic process was significantly enriched in all anther stages, and many saccharides and starch synthase-related genes, such as invertase, sucrose synthase, and starch branching enzyme, were significantly different expressed in HS compared with CK. Furthermore, co-expression network analysis showed a module (midnightblue) strongly consistent with HS, and two hub genes (CsaV3_6G004180 and CsaV3_5G034860) were found with a high degree of connectivity to other genes. Our results provide comprehensive understandings on male flower development in cucumber under HS.

Fusarium wilt results in undesirable effects on the quality and production of chieh-qua (Benincasa hispida Cogn. var. Chieh-qua How). Fusaric acid (FA), a secondary metabolite of biotin produced by pathogens of genus Fusarium, induced resistant responses in chieh-qua; however, the physiological and molecular mechanism(s) of FA resistance remains largely unknown. In our study, 'A39' (FA-resistant cultivar) exhibited decreased malondialdehyde (MDA) content and increased superoxide dismutase (SOD) enzyme activity when exposed to FA compared with 'H5' (FA-susceptible cultivar). More apoptosis cells existed in 'H5' than 'A39' after 2 days of FA treatment. RNA-seq results revealed that a total of 2968 and 3931 differentially expressed genes (DEGs) were detected under normal conditions (1562 up-regulated and 1406 down-regulated) and FA treatment (2243 up-regulated and 1688 down-regulated), respectively. Interestingly, DEGs associated with pathogen-related protein and ethylene (ET) biosynthesis and signal pathways were most significantly changed during FA stress. Notably, several crucial genes encoding pathogenesis-related protein (CL4451.Contig2, CL2175.Contig4), peroxidase (Unigene49615 and CL11695.Contig2), and ET-responsive transcription factors (TFs) (CL9320.Contig1, CL9849.Contig3, CL6826.Contig2, CL919. Contig6, and CL518.Contig7) were specifically induced after FA treatment. Collectively, the study provides molecular data for isolating candidate genes involved in FA resistance, especially ET related genes in chieh-qua.

Background Photosynthesis is a fundamental process for plant growth and development dependent on a precise network, including formation of chloroplast and chlorophyll synthesis. Chloroplast development deficiency could lead to albinism in higher plant. Results Here, we report a cucumber albino recessive mutant that processed white cotyledons under light condition and is unable to produce first true leaf. Meanwhile, albino mutant could grow out creamy green cotyledons under dark condition but died after exposing to light. Using fluorescence microscopy and transmission electron microscope (TEM), impaired chloroplasts were observed. We identified 7 and 3 differentially expressed genes (DEG) involved in Chlorophyll metabolism and Methylerythritol 4-phosphate (MEP) pathway through transcriptome analysis, respectively. We also examined the reported homologous genes for albino mutants from other plants. Two of 12 genes, TOC159 and DXS1, were up-regulated in cucumber albino mutants as well. The reliability of RNA sequencing results were further confirmed by real-time quantitative PCR (qPCR). Conclusions Taken together, we elaborate the differences between albino mutant and normal seedlings from a single cucumber progeny. This mutant is a new material to study protoplast development.

Heat stress is a major environmental factor limiting plant productivity and quality in agriculture. Cucumber, one of the most important vegetables among cucurbitaceae, prefers to grow in a warm environment. Until now the molecular knowledge of heat stress in cucumber remained unclear. In this study, we performed transcriptome analysis using two diverse genetic cucumber cultivars, L-9 and A-16 grown under normal and heat stress. L-9 displayed heat-tolerance phenotype with higher superoxide dismutase enzyme (SOD) enzyme activity and lower malondialdehyde (MDA) content than A-16 under heat stress. RNA-sequencing revealed that a total of 963 and 2778 genes are differentially expressed between L-9 and A-16 under normal and heat stress respectively. In addition, we found that differentially expressed genes (DEGs) associated with plant hormones signally pathway, transcription factors, and secondary metabolites showed significantly change in expression level after heat stress, which were confirmed by quantitative real-time PCR assay. Our results not only explored several crucial genes involved in cucumber heat resistance, but also provide a new insight into studying heat stress.

Drought, one of the crucial environmental constraints, seriously threats the quality and yield in chieh-qua. Therefore, cultivating drought-tolerant variety is greatly necessary for its normal growth under water deficiency. However, at present, molecular knowledge on drought resistance is mostly unclear in chieh-qua. In the study, characteristics of two diverse genetic chieh-qua variety, A39 (drought-resistance) and H5 (drought-sensitivity), were analyzed. Under drought stress, H5 exerted high water loss rate, increased malonaldehyde (MDA) content, and decreased enzyme activity of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) compared with A39. In addition, based on the transcriptome results, we obtained a total of 1821 (511 up-regulated and 1310 down-regulated) and 2114 (1282 up-regulated and 832 down- regulated) differentially expressed genes (DEGs) in the A39 versus H5 under normal and water-deficiency stress, respectively. Several DEGs involved in the cuticle synthesis (cytochrome P450 genes: CYP94A2, CYP86B1, CYP86A7), carbohydrate metabolism, and plant hormone signal transduction (small auxin-up RNA genes: SAUR32, SAUR72; JA-induced genes: TIFY 10A, TIFY 10C; ABA related genes: PYL2, PYL4) were explored and related to drought resistance. These expression patterns observed in the RNA-seq data were further confirmed with quantitative real-time PCR (qRT-PCR). In all, these results not only provided a new insight into analyzing genes of drought response, but also laid a foundation for isolating crucial genes involved in drought stress in chieh-qua.

Temperature rising caused by global warming has imposed significant negative effects on crop qualities and yields. To get the well-known molecular mechanism upon the higher temperature, we carefully analyzed the RNA sequencing-based transcriptomic responses of two contrasting chieh-qua genotypes: A39 (heat-tolerant) and H5 (heat-sensitive). In this study, twelve cDNA libraries generated from A39 and H5 were performed with a transcriptome assay under normal and heat stress conditions, respectively. A total of 8705 differentially expressed genes (DEGs) were detected under normal conditions (3676 up-regulated and 5029 down-regulated) and 1505 genes under heat stress (914 up-regulated and 591 down-regulated), respectively. A significant positive correlation between RNA-Seq data and qRT-PCR results was identified. DEGs related to heat shock proteins (HSPs), ubiquitin-protein ligase, transcriptional factors, and pentatricopeptide repeat-containing proteins were significantly changed after heat stress. Several genes, which encoded HSPs (CL2311.Contig3 and CL6612.Contig2), cytochrome P450 (CL4517.Contig4 and CL683.Contig7), and bHLH TFs (CL914.Contig2 and CL8321.Contig1) were specifically induced after four days of heat stress. DEGs detected in our study between these two contrasting cultivars would provide a novel basis for isolating useful candidate genes of heat stress responses in chieh-qua.

Heat stress (HS) negatively influences plant development and growth, especially production and quality. Cucumber is a widely cultivated plant in the gourd family Cucurbitaceae that is often exposed to high temperatures during summer and protected cultivation. In this study, we performed whole-genome re-sequencing of two pools, one heat-tolerant and one heat-sensitive, of the F-2 population derived from L-9 (heat-resistant) and A-16 (heat-sensitive). The genetic analysis showed that the heat resistance of L-9 cucumber seedlings was controlled by a single recessive gene. By combining bulked segregant analysis (BSA) technology, the crucial gene related to HS was preliminarily mapped to a 1.08-Mb region on chromosome 1. To fine-map the locus, Indel markers were designed according to the genomic sequence. Finally, the gene was narrowed to a 550-kb region flanked by two Indel markers, namely Indel-H90 and Indel-H224, that contained 56 candidate genes. Re-sequencing results indicated that 10 candidate genes among the 56 in the candidate region showed single base pair differences in the exons. Quantitative reverse-transcription polymerase chain reaction showed that 6 genes among the 10 candidate genes were significantly decreased when exposed to high temperatures. These results not only were useful for the isolation and characterization of the key genes involved in HS but also provided a basis for understanding the mechanism of heat tolerance regulation.