Characterization of the ABC Transporter G Subfamily in Pomegranate and Function Analysis of PgrABCG14.

ATP-binding cassette subfamily G (ABCG) proteins play important roles in plant growth and development by transporting metabolites across cell membranes. To date, the genetic characteristics and potential functions of pomegranate ABCG proteins (PgrABCGs) have remained largely unknown. In this study, we found that 47 PgrABCGs were divided into five groups according to a phylogenetic analysis; groups I, II, III, and IV members are half-size proteins, and group V members are full-size proteins. PgrABCG14, PgrABCG21, and PgrABCG47 were highly expressed in the inner seed coat but had very low expression levels in the outer seed coat, and the expression levels of these three PgrABCG genes in the inner seed coats of hard-seeded pomegranate 'Dabenzi' were higher than those of soft-seeded pomegranate 'Tunisia'. In addition, the expression of these three PgrABCG genes was highly correlated with the expression of genes involved in lignin biosynthesis and hormone signaling pathways. The evolution of PgrABCG14 presents a highly similar trend to the origin and evolution of lignin biosynthesis during land plant evolution. Ectopic expression of PgrABCG14 in Arabidopsis promoted plant growth and lignin accumulation compared to wild type plants; meanwhile, the expression levels of lignin biosynthesis-related genes (CAD5, C4H, and Prx71) and cytokinin response marker genes (ARR5 and ARR15) were significantly upregulated in transgenic plants, which suggests the potential role of PgrABCG14 in promoting plant growth and lignin accumulation. Taken together, these findings not only provide insight into the characteristics and evolution of PgrABCGs, but also shed a light on the potential functions of PgrABCGs in seed hardness development.

PpybZIP43 contributes to sucrose synthesis in pear fruits by activating PpySPS3 expression and interacts with PpySTOP1.

Sucrose is an important factor affecting sweetness and flavor in pear fruits, but the molecular mechanism of sucrose synthesis regulation is relatively unknown. Here, we characterized a transcription factor gene from pear (Pyrus pyrifolia Nakai cv. "Hosui") fruits, PpybZIP43, and found that the transient overexpression of PpybZIP43 in pear fruits significantly increased the sucrose content and the relative expression level of sucrose phosphate synthase genes (PpySPS3 and PpySPS8). Subcellular localization analysis in tobacco leaves showed that PpybZIP43 was localized in the nucleus. Yeast one-hybrid, electrophoretic mobility shift assay (EMSA), and dual-luciferase reporter assays indicated that PpybZIP43 was able to activate the expression of PpySPS3 by binding specifically to the G-box (CACGTG) element in the promoter. The protein-protein interaction assays using yeast two-hybrid, bimolecular fluorescence complementation (BiFC), firefly luciferase complementation imaging (LCI), and glutathione S-transferase (GST) pull-down demonstrated that PpybZIP43 could directly interact with PpySTOP1 to form a transcription complex. This study is helpful for understanding the molecular basis of sucrose synthesis and accumulation in pear fruits and provides candidate genes for breeding.

Genomics and Prognosis Analysis of N6-Methyladenosine Regulators in Lung Adenocarcinoma.

Objective: N6-methyladenosine (m6A) modification is involved in modulating various biological processes in human cancers. But the implication of m6A modification in lung adenocarcinoma (LUAD) is still unclear. Hence, this study conducted a comprehensive analysis of the expression and clinical implication of m6A regulators in LUAD. Methods: Consensus clustering analysis of 502 LUAD samples in the TCGA dataset was presented based on the expression profiles of 20 m6A regulators using ConsensusClusterPlus package. Overall survival (OS), activation of signaling pathways and tumor immunity (immune/stromal score, tumor purity, expression of HLA and immune checkpoints, and immune cell infiltration) were compared between m6A modification patterns. The m6A-related genes between patterns were identified and prognostic m6A-related genes were imported into LASSO-cox regression analysis. The m6A risk score was developed and its prognostic implication was evaluated and externally verified in the GSE30219 and GSE72094 dataset. Furthermore, a nomogram that contained independent prognostic indicators was established, followed by external verification. Results: Two m6A modification patterns were clustered across LUAD based on the expression similarity of the m6A regulators via consensus clustering analysis, with distinct OS, activation of signaling pathways and tumor immunity. Totally, 213 m6A-related genes that were identified by comparing two patterns were significantly related to LUAD prognosis. By LASSO method, we constructed the m6A risk score that was a reliable and independent prognostic factor for LUAD. Patients with low m6A risk score displayed a prominent survival advantage. After incorporating independent clinical features, we developed the prognostic nomogram that exhibited high predictive accuracy and the best clinical net benefit for OS. Conclusion: Collectively, our study may provide a clinically useful tool for precise prognostic management and optimization of immunotherapeutic strategies for LUAD patients.

Spatio-temporally expressed sorbitol transporters cooperatively regulate sorbitol accumulation in pear fruit.

Sorbitol is the primary substrate translocated from source to sink in pear species. Among the many sorbitol transporters (SOTs), some are known to be involved in sorbitol accumulation in fruit; however, their particular roles are unclear. In this study, we examined the transcriptome and metabolome of a variety of pear samples from six time points to identify those SOTs. Similar to previous studies, sorbitol and sucrose differed significantly between the leaf and fruit, and sorbitol was consistently observed at higher concentrations at all time points. Interestingly, we found that sorbitol accumulation in pear fruit was cooperatively mediated by SOT3, SOT6/20, SOT19/21, and SOT22. In particular, the up-regulated SOT6/20 and SOT19/21 in fruit under 1 mg L-1 abscisic acid and 10 mg L-1 indole acetic acid treatments, respectively, resulted in an increased sorbitol concentration. In addition, sorbitol concentration showed positive correlations to fructose and glucose concentrations, indicating a role for sorbitol in the determination of fruit sweetness. Together with the deduced process of sugar biosynthesis, transport, conversion, and accumulation in pear, our study provides a foundation for further research into sugar accumulation processes in pear fruit, contributing to the improvement of fruit quality.

Transcriptome Analysis of Low- and High-Sucrose Pear Cultivars Identifies Key Regulators of Sucrose Biosynthesis in Fruits.

Sucrose accumulation is one of the important factors that determine fruit enlargement and quality. Evaluation of the sugar profile of 105 pear cultivars revealed low-sucrose and high-sucrose (HS) types of pear fruits. To better understand the molecular mechanisms governing the sucrose content of pear fruits, this study performed transcriptome analysis during fruit development using low-sucrose 'Korla' fragrant pear and HS 'Hosui' pear, and a coexpression module uniquely associated with the control of high-sucrose accumulation was identified by weighted gene coexpression network analysis. These results suggested that there are seven candidate genes encoding key enzymes (fructokinase, glucose-6-phosphate isomerase, sucrose phosphate synthase and sucrose synthase) involved in sucrose biosynthesis and several transcription factors (TFs) whose expression patterns correlate with those of genes associated with sucrose biosynthesis. This correlation was confirmed by linear regression analysis between predicted gene expression and sucrose content in different pear cultivars during fruit development. This study provides insight into the molecular mechanism underlying differences in sucrose content across pear cultivars and presents candidate structural genes and TFs that could play important roles in regulating carbohydrate partitioning and sucrose accumulation.

Investigations into the production of volatile compounds in Korla fragrant pears (Pyrus sinkiangensis Yu).

The composition of volatile compounds in Korla fragrant pears was determined using headspace solid-phase microextraction followed by a gas chromatography-mass spectrometry analysis using fruits at 30, 90, and 150 days after bloom. Hexanal, (E)-2-hexenal, 1-hexanol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, and hexyl acetate were identified as the major compounds. The composition of volatile compounds was associated with fatty acid concentrations and key enzyme activity in the lipoxygenase pathway. In vitro linoleic and linolenic acid feeding experiments conducted using cubes of fruit flesh demonstrated that the concentrations of volatile esters, such as hexyl acetate, in the treated fruits increased significantly after incubation for 12 h compared with those in the control fruits, which was accompanied by a reduction in aldehyde and alcohol concentrations (p < 0.05 or p < 0.01). However, the treatments did not significantly influence the enzyme activity and expression of genes encoding the enzymes.

Genome-wide analysis of polygalacturonase gene family from pear genome and identification of the member involved in pear softening.

BACKGROUND: Polygalacturonase (PG), as an important hydrolase participating in the degradation of pectin, plays an important role in softening process of fruit. However, information on PG gene family in pear genome and the specific member involved in fruit softening is still rudimentary. RESULTS: In this study, a total of 61 PG genes, which could be divided into six subclasses, were identified from the pear genome with diverse chromosome locations, gene structures, motifs and cis-acting elements. Most PbrPGs were derived from WGD/segmental duplication blocks, and purifying selection was the main driving force for their expansion. The expression profiles of PbrPGs in pear were tissue/development-stage/cultivar-dependent. During 'Housui' pear storage, associated with the reduction of firmness was the accumulation of PG activity. Totally, 28 PbrPGs were expressed during fruit storage, which could be classified into five categories based on different expression patterns; most demonstrated an increased trend. Of these, PbrPG6 were proposed to account for pear softening in combination of the phylogenetic and correlation analysis among firmness, PG activity and PbrPGs. By constructing the silencing vector, a higher firmness was observed in PbrPG6-silenced fruit when compared with that of the control (empty vector). In a further study, we found that the expression of PbrPG6 was regulated by postharvest 1-MCP/ethrel treatment, and several PbrERFs might function in this process. CONCLUSIONS: We identified 61 PbrPG genes from pear genome; of these, PbrPG6 was involved in fruit softening process; furthermore, the expression of PbrPG6 might be under the control of PbrERF. This study provides a foundation for future work aimed at elucidating the molecular mechanism underlying pear softening.

First genome sequence of a blaKPC-2-carrying Citrobacter koseri isolate collected from a patient with diarrhoea.

OBJECTIVES: The blaKPC gene is rarely reported in Citrobacter koseri. Here we report the first draft genome sequence of a blaKPC-2-carrying C. koseri isolate from a patient with diarrhoea. METHODS: Transferability of the blaKPC-2-bearing plasmid was determined by the filter mating method. The whole genome sequence of C. koseri L168 was determined using an Illumina HiSeq platform. The genome was de novo assembled using Velvet 1.2.10. Acquired antimicrobial resistance genes and plasmid replicons were identified using ResFinder 2.1 and PlasmidFinder 1.3, respectively. RESULTS: Antimicrobial susceptibility testing (AST) showed that C. koseri L168 was resistant to multiple antibiotics but was susceptible to ciprofloxacin, gentamicin, tobramycin, amikacin, tigecycline and colistin. A KPC-2-harbouring plasmid was conjugative and the transconjugants conferred increased resistance to carbapenems confirmed by conjugation experiments and AST. In silico analysis revealed the presence of the ß-lactam resistance genes blaKPC-2 and blaMAL-1. Additionally, plasmids of incompatibility groups IncFII and IncX4 were identified in the genome by PlasmidFinder. BLAST analysis revealed that blaKPC-2 was located on a Tn3 transposon element in C. koseri L168 with the conserved linear structure ISKpn27-blaKPC-2-ΔISKpn6-korC-klcA. CONCLUSIONS: To our knowledge, this is only the second report of C. koseri producing KPC-2, and we report the first draft genome sequence of a blaKPC-2-carrying C. koseri isolate from a patient with diarrhoea in China. This work may facilitate our understanding of the pathogenesis, multidrug resistance mechanisms and genomic features of this species. Further monitoring of bacteria carrying carbapenemase genes in patients' gut microbiota is warranted.

Genome-wide identification, evolution, and expression analysis of the KT/HAK/KUP family in pear.

The K+ transporter/high-affinity K+/K+ uptake (KT/HAK/KUP) family, as one of the largest K+ transporter families in higher plants, plays an essential role in plant growth, mineral element absorption, salt stress tolerance, and other physiological processes. However, little is known about this family in pear (Pyrus). Here, we identified 20 K+ transporter genes in pear (P. bretschneideri) using genome-wide analysis. Their gene structure, chromosomal distribution, conserved motifs, phylogenetics, duplication events, and expression patterns were also examined. The results of phylogenetic analysis showed that PbrKT/HAK/KUP genes were clustered into three major groups (Groups I-III). Among the 20 PbrKT/HAK/KUP genes, 18 were mapped to nine chromosomes and two to scaffolds. Four WGD/segmental gene pairs were identified, indicating that WGD/segmental duplication may have contributed to the expansion of the KT/HAK/KUP family in pear. Among the four pairs of WGD/segmentally duplicated genes, both members of three pairs had been subjected to purifying selection, whereas the fourth pair had been subjected to positive selection. Furthermore, phenotypic experiments showed that the growth of pear seedlings was affected by potassium deficiency treatment. Expression patterns of 20 PbrKT/HAK/KUP genes in roots were further assayed with qRT-PCR. PbrHAK1 and PbrHAK12/16 were significantly expressed in response to K+ deficiency, suggesting that these genes are crucial for K+ uptake in pear, especially under the condition of K+ starvation. Our results provide a foundation for further study on the function of KT/HAK/KUP genes in pear.

Diversification and independent domestication of Asian and European pears.

BACKGROUND: Pear (Pyrus) is a globally grown fruit, with thousands of cultivars in five domesticated species and dozens of wild species. However, little is known about the evolutionary history of these pear species and what has contributed to the distinct phenotypic traits between Asian pears and European pears. RESULTS: We report the genome resequencing of 113 pear accessions from worldwide collections, representing both cultivated and wild pear species. Based on 18,302,883 identified SNPs, we conduct phylogenetics, population structure, gene flow, and selective sweep analyses. Furthermore, we propose a model for the divergence, dissemination, and independent domestication of Asian and European pears in which pear, after originating in southwest China and then being disseminated throughout central Asia, has eventually spread to western Asia, and then on to Europe. We find evidence for rapid evolution and balancing selection for S-RNase genes that have contributed to the maintenance of self-incompatibility, thus promoting outcrossing and accounting for pear genome diversity across the Eurasian continent. In addition, separate selective sweep signatures between Asian pears and European pears, combined with co-localized QTLs and differentially expressed genes, underline distinct phenotypic fruit traits, including flesh texture, sugar, acidity, aroma, and stone cells. CONCLUSIONS: This study provides further clarification of the evolutionary history of pear along with independent domestication of Asian and European pears. Furthermore, it provides substantive and valuable genomic resources that will significantly advance pear improvement and molecular breeding efforts.

Draft Genome Sequence of Staphylococcus microti DSM 22147, Isolated from the Common Vole.

Staphylococcus microti DSM 22147 was isolated from viscera of common voles (Microtus arvalis Pallas) with generalized Brucella microti infection in the Czech Republic. To the best of our knowledge, the genome sequence of the species S. microti has not been previously studied. The complete genome sequence of strain DSM 22147 includes a genome of 2,381,859 bp (38.0% GC content) without any plasmids.

The gene PbTMT4 from pear (Pyrus bretschneideri) mediates vacuolar sugar transport and strongly affects sugar accumulation in fruit.

Tonoplast monosaccharide transporters (TMTs) play important roles in vacuolar sugar accumulation in plants. In this study, six TMT genes (PbTMT1-6) were identified in the Pyrus bretschneideri genome database, and their expression profiles were correlated with soluble sugar contents during the pear (P. bretschneideri cv. Ya Li) fruit development process. Subsequently, PbTMT4 was identified as a strong contributor to fructose, glucose and sucrose accumulation in fructescence of pears. Heterologous expression of PbTMT4, in the hexose transporter-deficient yeast strain EBY.VW4000, facilitated growth in media containing low levels of glucose, fructose, sucrose or sorbitol. In addition, PbTMT4-transformed tomato plants flowered and bore fruit significantly earlier than wild-type (WT) plants, and glucose and fructose levels in mature tomatoes were increased by about 32 and 21% compared with those in WT plants. However, no obvious alterations in sucrose content, plant height and weight per fruit were observed. Finally, subcellular localization experiments in transformed Arabidopsis plants showed that PbTMT4 is localized to tonoplast vesicles of protoplasts. These preliminary results suggest that PbTMT4 participates in vacuolar accumulation of sugars, and thus affects plant growth and development.

Expansion and evolutionary patterns of cysteine-rich peptides in plants.

BACKGROUND: Cysteine-rich peptides (CRPs) are gaining recognition as regulators of cell-cell communication in plants. RESULTS: We identified 9556 CRPs in 12 plant species and analysed their evolutionary patterns. In most angiosperm plants, whole genome duplication and segmental duplication are the major factors driving the expansion of CRP family member genes, especially signal peptides. About 30% of the CRP genes were found clustered on the chromosomes, except in maize (Zea mays). Considerable collinearities between CRP genes between or within species reveal several syntenic regions on the chromosomes. Different subfamilies display diverse evolutionary rates, suggesting that these subfamilies are subjected to different selective pressures. CRPs in different duplication models also show contrasting evolutionary rates, although the underlying mechanism is unclear because of the complexity of gene evolution. The 1281 positively selected genes identified are probably generated within a certain period of time. While most of these belonged to maize and sorghum (Sorghum bicolor), new CRP functions would also be expected. Up-regulation of 10 CRPs was observed in self-pollinated pear pistils and pollen tubes under self S-RNase treatments in vitro. The expression divergence between different CRP gene duplication types suggests that different duplication mechanisms affected the fate of the duplicated CRPs. CONCLUSION: Our analyses of the evolution of the CRP gene family provides a unique view of the evolution of this large gene family.

A Novel NAC Transcription Factor, PbeNAC1, of Pyrus betulifolia Confers Cold and Drought Tolerance via Interacting with PbeDREBs and Activating the Expression of Stress-Responsive Genes.

NAC (NAM, ATAF, and CUC) transcription factors are important regulator in abiotic stress and plant development. However, knowledge concerning the functions of plant NAC TFs functioning in stress tolerance and the underlying molecular basis are still limited. In this study, we report functional characterization of the NAC TF, PbeNAC1, isolated from Pyrus betulifolia. PbeNAC1 were greatly induced by cold and drought, while salt stress had little effect on expression. PbeNAC1 was localized in the nuclei showed transactivation activity. Overexpression of PbeNAC1 conferred enhanced tolerance to multiple stresses, including cold and drought, as supported by lower levels of reactive oxygen species, higher survival rate, higher activities of enzymes, relative to wild-type (WT). In addition, steady-state mRNA levels of 15 stress-responsive genes coding for either functional or regulatory proteins were higher levels in the transgenic plants relative to the WT with drought or cold treatment. yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that PbeNAC1 protein can physically interact with PbeDREB1 and PbeDREB2A. Taken together, these results demonstrate that pear PbeNAC1 plays an important role in improving stress tolerance, possibly by interacting with PbeDREB1 and PbeDREB2A to enhance the mRNA levels of some stress-associated genes.

A New Insight into the Evolution and Functional Divergence of SWEET Transporters in Chinese White Pear (Pyrus bretschneideri).

SWEET genes are a recently identified plant gene family that play an indispensable role in sugar efflux. However, no systematic study has been performed in pear. In this research, 18 SWEET transporters identified in pear, almost twice the number found in woodland strawberry and Japanese apricot, were divided into four clades. Conserved motifs and six exons of the SWEET transporters were found in six species. SWEET transporters contained seven transmembrane segments (TMSs) that evolved from an internal duplication of an ancestral three-TMSs unit, connected by TMS4. This is the first direct evidence identifying internal repeats through bioinformatics analysis. Whole-genome duplication (WGD) or segmental duplication and dispersed duplication represent the main driving forces for SWEET family evolution in six species, with former duplications more important in pear. Gene expression results suggested that PbSWEET15 and PbSWEET17 have no expression in any tissues because of critical lost residues and that 62.5% of PbSWEET duplicate gene pairs have functional divergence. Additionally, PbSWEET6, PbSWEET7 and PbSWEET14 were found to play important roles in sucrose efflux from leaves, and the high expression of PbSWEET1 and PbSWEET2 might contribute to unloading sucrose from the phloem in the stem. Finally, PbSWEET5, PbSWEET9 and PbSWEET10 might contribute to pollen development. Overall, our study provides important insights into the evolution of the SWEET gene family in pear and four other Rosaceae, and the important candidate PbSWEET genes involved in the development of different tissues were identified in pear.

Evolution of the aroma volatiles of pear fruits supplemented with fatty acid metabolic precursors.

To examine the biochemical metabolism of aroma volatiles derived from fatty acids, pear fruits were incubated in vitro with metabolic precursors of these compounds. Aroma volatiles, especially esters, were significantly increased, both qualitatively and quantitatively, in pear fruits fed on fatty acid metabolic precursors. Cultivars having different flavor characteristics had distinctly different aroma volatile metabolisms. More esters were formed in fruity-flavored "Nanguoli" fruits than in green-flavored "Dangshansuli" fruits fed on the same quantities of linoleic acid and linolenic acid. Hexanal and hexanol were more efficient metabolic intermediates for volatile synthesis than linoleic acid and linolenic acid. Hexyl esters were the predominant esters produced by pear fruits fed on hexanol, and their contents in "Dangshansuli" fruits were higher than in "Nanguoli" fruits. Hexyl esters and hexanoate esters were the primary esters produced in pear fruits fed on hexanal, however the content of hexyl ester in "Dangshansuli" was approximately three times that in "Nanguoli". The higher contents of hexyl esters in "Dangshansuli" may have resulted from a higher level of hexanol derived from hexanal. In conclusion, the synthesis of aroma volatiles was largely dependent on the metabolic precursors presented.

Molecular cloning and expression analysis of a gene for sucrose transporter from pear (Pyrus bretschneideri Rehd.) fruit.

Here we report the cloning of a sucrose transporter cDNA from pear (Pyrus bretschneideri Rehd. cv 'Yali') fruit and an analysis of the expression of the gene. A cDNA clone, designated PbSUT1 was identified as a sucrose transporter cDNA from its sequence homology at the amino acid level to sucrose transporters that have been cloned from other higher plant species. PbSUT1 potentially encoded a protein of 499 amino acid residues with a predicted molecular mass of 53.4 kDa and an isoelectric point (pI) of 9.21. Phylogenetic analysis revealed that the PbSUT1 belonged to type III SUTs and was more closely related to the MdSUT1 from apple fruit. Some major facilitator superfamily (MFS)-specific sequence motifs were found in the predicted PbSUT1 peptides, and an MFS_1 domain was located at the amino acid positions of 29-447 of the sequence. A study of gene expression along fruit development showed that PbSUT1 transcripts are present at all stages but significantly increase before fruit enlargement and during the ripening process with increasing sucrose levels. In contrast, the expression levels don't change much during the period of rapid fruit growth. This work shows that sucrose transporter may play a role in the accumulation of sugars during maturation and in maintaining the internal cellular distribution.

The genome of the pear (Pyrus bretschneideri Rehd.).

The draft genome of the pear (Pyrus bretschneideri) using a combination of BAC-by-BAC and next-generation sequencing is reported. A 512.0-Mb sequence corresponding to 97.1% of the estimated genome size of this highly heterozygous species is assembled with 194× coverage. High-density genetic maps comprising 2005 SNP markers anchored 75.5% of the sequence to all 17 chromosomes. The pear genome encodes 42,812 protein-coding genes, and of these, ~28.5% encode multiple isoforms. Repetitive sequences of 271.9 Mb in length, accounting for 53.1% of the pear genome, are identified. Simulation of eudicots to the ancestor of Rosaceae has reconstructed nine ancestral chromosomes. Pear and apple diverged from each other ~5.4-21.5 million years ago, and a recent whole-genome duplication (WGD) event must have occurred 30-45 MYA prior to their divergence, but following divergence from strawberry. When compared with the apple genome sequence, size differences between the apple and pear genomes are confirmed mainly due to the presence of repetitive sequences predominantly contributed by transposable elements (TEs), while genic regions are similar in both species. Genes critical for self-incompatibility, lignified stone cells (a unique feature of pear fruit), sorbitol metabolism, and volatile compounds of fruit have also been identified. Multiple candidate SFB genes appear as tandem repeats in the S-locus region of pear; while lignin synthesis-related gene family expansion and highly expressed gene families of HCT, C3'H, and CCOMT contribute to high accumulation of both G-lignin and S-lignin. Moreover, alpha-linolenic acid metabolism is a key pathway for aroma in pear fruit.

Evaluation of the volatile profile of 33 Pyrus ussuriensis cultivars by HS-SPME with GC-MS.

Evaluation of the volatile compounds in fruit provides useful information for plant breeding for improved fruit aroma. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to assess the volatile profile of 33 cultivars of the Chinese pear Pyrus ussuriensis. In all, 108 volatile compounds were identified and there were significant differences in the composition and concentration of volatiles among cultivars. On the basis of principal components analysis (PCA), the cultivars could be divided into four groups: Group 1 contained Reli, Jinxiang, Hongbalixiang, Baibalixiang and Fuwuxiang, cultivars with a high concentration of esters and a low concentration of hydrocarbons. Group 2 contained Qiuxiang, Fuanjianba, Longxiang, Guanhongxiao, Shanli24 and Wuxiangli, cultivars with high concentrations of hydrocarbons and low concentrations of esters. Group 3 contained Shatangli and Manyuanxiang, cultivars with high concentrations of aldehydes. Group 4 contained the other 25 cultivars.