Figures (4)  Tables (2)

    • Figure 1. 

      Cambial regeneration process after ring-barking for agarwood formation. (a) On-site bark ring-barking of agarwood; (b) the trunk sections with regenerated phloem layers removed at 15, 85, and 135 d after bark removal; (c) samples of the regenerated phloem layers at 35, 50, 119, and 135 d after bark removal; (d) abbreviations: rph - regenerated phloem; xy - xylem vessels; (e) bar chart of ethanol extract content: changes from 35 to 135 d. * Indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001. (f) High-performance liquid chromatography (HPLC) characteristic peak chart.

    • Figure 2. 

      Differential gene expression among samples at 15, 68, and 100 d after agarwood formation. (a) Pearson correlation heat map for three different stages at 15, 68, and 100 d after implantation, with three replicates, totaling nine white Aquilaria samples; (b) bar chart of differentially expressed genes at three different stages after implantation. UP indicates the number of upregulated genes, DOWN indicates the number of downregulated genes; (c) Venn diagram of the differentially expressed genes at three different stages after implantation at 15, 68, and 100 d.

    • Figure 3. 

      Expression levels of differential agarwood genes at various stages of formation. The bar chart represents the transcriptomic expression levels, while the line chart represents the fluorescence quantitative expression levels. Gene symbols: ATOB: acetyl-CoA C-acetyltransferase; FDFTO: farnesyl-diphosphate farnesyltransferase; FDPS: farnesyl-diphosphate synthase; FLDH: NAD+-dependent farnesol dehydrogenase; GDPS: geranyl-diphosphate synthase; GGPS: geranylgeranyl diphosphate synthase; ISPH: 4-hydroxy-3-methylbut-2-en-1-yI diphosphate reductase.

    • Figure 4. 

      Expression of differential genes in the sesquiterpene biosynthetic pathway. Abbreviations: Acetyl-CoA: acetyl-CoA; Acetoacetyl-CoA: acetoacetyl-CoA; HMG-CoA: 3-hydroxy-3-methylglutaryl-CoA; MVA: mevalonic acid; MVAP: phosphomevalonic acid; MVAPP: mevalonate diphosphate; IPP: isopentenyl diphosphate; DMAPP: dimethylallyl diphosphate; PA + G3P: pyruvic acid + glyceraldehyde 3-phosphate; DXP: 1-deoxy-D-xylulose 5-phosphate; MEP: 2-C-methyl-D-erythritol 4-phosphate; CDP-ME: cytidine diphosphate-2-C-methyl-D-erythritol; CDP-MEP: cytidine diphosphate-2-C-methyl-D-erythritol 2-phosphate; MEcPP: 2-C-methyl-D-erythritol 2,4-cyclodiphosphate; HMBPP: 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate. ATOB: acetyl-CoA C-acetyltransferase; HMGCS: hydroxymethylglutaryl-CoA synthase; HMGCR: hydroxymethylglutaryl-CoA reductase (NADPH); MVAK1: mevalonate kinase; MVAD: diphosphomevalonate decarboxylase; IDI: isopentenyl-diphosphate Delta-isomerase; DXS: 1-deoxy-D-xylulose-5-phosphate synthase; DXR: 1-deoxy-D-xylulose-5-phosphate reductoisomerase; ISPD: 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase; ISPE: 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase; ISPF: 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase; ISPG: (E)-4-hydroxy-3-methylbut-2-enyl- di phosphate synthase.

    • No. Retention time (min) Name CAS Relative content
      1 6.296 Benzaldehyde 100-52-7 0.61
      2 13.645 Benzaldehyde, 4-(1-methylethyl)- 122-03-2 1.25
      3 21.409 Isoaromadendrene epoxide 1000159-36- 6 0.06
      4 21.885 Cyclohexane, 1-butenylidene- 36144-40-8 0.08
      5 22.14 Bicyclo[2.2.1]heptane-2,5-diol, 1,7,7-trimethyl-, (2-endo,5-exo)- 10359-41- 8 0.14
      6 23.066 Alloaromadendrene 10359-41-8 0.1
      7 23.125 (+)-2-Carene, 2-acetyl 1000151- 09-7 0.07
      8 23.321 .beta.-Clovene 1000163- 00-2 0.06
      9 23.423 .alpha.-Maaliene 489-28-1 0.16
      10 23.499 .beta.-Panasinsene 1000159- 39-0 0.07
      11 23.61 cis-Thujopsene 470-40-6 0.45
      12 23.797 Agarospirol 1460-73-7 1.08
      13 23.899 Patchoulene 1405-16-9 0.07
      14 24.162 Aromadendrene oxide-(1) 1000151- 98-4 0.43
      15 24.23 Arctiol 36061-11- 7 0.38
      16 24.323 3,5,11-Eudesmatriene 193615- 07-5 0.06
      17 24.476 Guaiol 489-86-1 0.15
      18 24.587 .gamma.-Gurjunenepoxide-(1) 1000156- 15-0 0.33
      19 24.697 Longipinocarvone 1000151- 87-1 0.31
      20 24.782 .alpha.-Guaiene 3691/12/1 0.07
      21 24.884 Caryophyllene 87-44-5 0.36
      22 25.224 Tetrahydrofuran-2-ol, 3,4-di[1-butenyl]- 1000131-84- 0 0.72
      23 25.377 cis-Z-.alpha.-Bisabolene epoxide 1000131- 71-2 0.37
      24 25.666 .beta.-Oplopenone 28305-60- 4 0.09
      25 25.734 13-nor-Eremophil-1(10)-en-11-one 54275-21- 7 0.09
      26 25.946 Spiro[adamantane-2,5'-[1.2]dioxolan]-3'-one, 4'-methylene- 126255- 68-3 0.73
      27 26.056 Nerolidol 142-50-7 0.37
      28 26.15 Isospathulenol 88395-46- 4 0.06
      29 26.252 .beta.-Humulene 116-04-1 0.12
      30 26.379 .alpha.-Cadinol 481-34-5 0.85
      31 26.456 Dehydroxy-isocalamendiol 1005276- 30-1 0.19
      32 26.558 Selin-6-en-4.alpha.-ol 118173- 08-3 0.33
      33 26.617 1,4,4,7a-Tetramethyl-2,4,5,6,7,7a-hexahydro-1H-indene-1,7-diol 121747- 53-3 0.12
      34 26.804 9-Tetradecenal, (Z)- 53939-27- 8 0.07
      35 26.872 Neointermedeol 5945-72-2 0.3
      36 27.059 Hexadecahydro-benzo[de]anthracene 1000371- 48-1 0.56
      37 27.161 E,E-6,8-Tridecadien-2-ol, acetate 1000131- 35-4 0.68
      38 27.203 Isolongifolol 1139-17-9 0.43
      39 27.331 1-Bromo-3-(2-bromoethyl)-nonane 70928-49- 3 0.39
      40 27.552 2,6,10-Dodecatrienal, 3,7,11-trimethyl-, (E,E)- 502-67-0 0.88
      41 27.704 Nootkatone 4674-50-4 5.63
      42 27.823 .beta.-Santalol 77-42-9 0.56
      43 28.019 1,1,4,7-Tetramethyldecahydro-1H-cyclopropa[e]azulene-4,7-diol 1212211- 43-2 0.34
      44 28.121 Arteannuin b 1000212- 12-6 0.9
      45 28.299 Isoshyobunone 1000360- 30-1 0.21
      46 28.444 1,8-Cyclopentadecadiyne 4722-42-3 0.75
      47 28.563 cis-Z-.alpha.-Bisabolene epoxide 1000131- 71-2 0.51
      48 28.656 Valerenol 101628- 22-2 2.76
      49 28.775 1,8,11,14-Heptadecatetraene, (Z,Z,Z)- 10482-53- 8 0.79
      50 28.834 Isobutyl (5-isopropyl-2-methylphenyl) carbonate 1000378- 27-3 0.25
      51 28.936 7-(2-Hydroxypropan-2-yl)-1,4a-dimethyldecahydronaphthalen-1-ol 92857-25- 5 0.72
      52 29.072 Nootkaton-11,12-epoxide 1000374- 20-3 0.17
      53 29.183 Nerolidyl acetate 2306-78-7 0.38
      54 29.429 6-(p-Tolyl)-2-methyl-2-heptenol, trans- 39599-18- 3 2.58
      55 29.59 Humulenol-II 19888-00- 7 0.78
      56 29.76 Silphiperfol-6-en-5-one 20405-58- 7 1.2
      57 29.905 L-Glutamine, N-ethoxycarbonyl-, methyl ester 1000452- 41-9 0.1
      58 29.973 6-Decen-4-yn-3-ol, 2-methyl-9-(2-methoxyethoxymethoxy)-, (E)- 1000156- 83-6 0.24
      59 30.1 Bohlmann k2631 80367-94- 8 4.55
      60 30.194 (3R,3aR,4aS,5R,9aS)-3,5,8-Trimethyl-3a,4,4a,5,6,7,9,9a-octahydroazuleno[6,5-b]furan-2(3H)-one 66873-38- 9 1.3
      61 30.279 1-(1-Adamantyl)-1-phenylethanol 303797- 64-0 0.68
      62 30.372 Valerenic acid 3569/10/6 0.87
      63 30.482 Ambrosin 509-93-3 3.08
      64 30.567 Isoaromadendrene epoxide 1000159- 36-6 1.99
      65 30.729 Acetate, 2-cyclohexenyl-3-[1-(2-oxopropyl)ethenyl]-2,4,4-trimethyl 1000196- 78-1 0.97
      66 30.831 Benzene, 1-isocyanato-2-methoxy- 700-87-8 0.2
      67 30.941 Valerenic acid, ethyl ester 1000453- 13-8 0.38
      68 31.001 Oxacyclotetradeca-4,11-diyne 6568-32-7 0.29
      69 31.145 Octanoic acid, 1-ethenyl-1,5-dimethyl-4-hexenyl ester 10024-64- 3 0.19
      70 31.298 Estr-4-en-3-one 4811-77-2 0.67
      71 31.434 Zederone 7727-79-9 0.68
      72 31.527 Spirafolide 130838- 06-1 0.36
      73 31.587 3-(Benzyloxymethyl)hex-5-ene-1,2-diol 1000192- 76-5 1.08
      74 31.689 7,10,13-Hexadecatrienoic acid, methyl ester 56554-30- 4 0.49
      75 31.893 1,8-Cyclopentadecadiyne 4722-42-3 0.07
      76 32.012 6-(1-Hydroxymethylvinyl)-4,8a-dimethyl-3,5,6,7,8,8a-hexahydro-1H-naphthalen-2-one 1000190- 51-4 0.78
      77 32.122 2,9-Heptadecadiene-4,6-diyn-8-ol, (Z,E)- 50816-77- 8 0.23
      78 32.216 Z,Z,Z-4,6,9-Nonadecatriene 1000131- 11-7 0.28
      79 32.309 trans-Valerenyl acetate 101527- 74-6 0.35
      80 32.7 Benzene, 1,1'-(1,6-hexanediyl)bis- 1087-49-6 0.17
      81 33.176 Cedran-diol, 8S,13- 8S, 13- 88588-48- 1 0.1
      82 33.286 7-Benzofuranol, 2,3-dihydro-2,2-dimethyl- 1563-38-8 0.16
      83 33.405 9-Octadecenal, (Z)- 2423/10/1 1.53
      84 33.906 1-Pentyn-3-ol, 1,4-diphenyl- 1000162- 87-4 0.38
      85 34.441 Picrotoxin 124-87-8 0.12
      86 34.509 1,1'-Butadiynylenedicyclohexanol 5768/10/5 0.14
      87 35.282 Reynosin 28254-53- 7 0.23
      88 36.098 1,1-Diacetoxy-9,9-diformylnona-2,4,6,8-tetraene 104970- 92-5 0.05
      89 36.812 8-Naphthol, 1-(benzyloxy)- 326875- 68-7 17.43
      90 38.103 Neoisolongifolene-8-ol 1000159- 36-9 0.06
      91 39.224 1-Heneicosanol 15594-90- 8 0.23
      92 40.116 Phthalic acid, propyl 6-ethyl-3-octyl ester 1000315- 17-3 0.11
      93 40.473 2-(2'-Methoxyphenethyl)chromone 1000422- 88-7 0.15
      94 40.864 7-Methoxy-2-phenethylchromone 1000422- 88-8 2.83
      95 40.991 Acetamide, 2-methoxy-2-phenyl-N-[2-(4-chlorophenyl)ethyl]- 327991- 45-7 9.12
      96 41.509 8-Methoxy-2-phenethylchromone 1000422- 89-0 0.12
      97 43.497 Fumaric acid, 2,4,4-trimethylpentyl dodec-2-en-1-yl ester 1000405- 61-4 12.16
      98 43.786 13-Docosenamide, (Z)- 112-84-5 0.57
      99 44.203 Squalene 111-02-4 0.48
      100 44.772 6,7-Dimethoxy-2-phenethyl-4H-chromen-4-one 84294-87- 1 1.84

      Table 1. 

      Chemical composition and relative content of agarwood essential oil.

    • No. Retention time (min) Name CAS Relative content
      1 21.409 Isoaromadendrene epoxide 1000159-36- 6 0.06
      2 23.066 Alloaromadendrene 10359-41-8 0.1
      3 23.321 β-Chloranil 1000163- 00-2 0.06
      4 23.423 α-Terpinene 489-28-1 0.16
      5 23.499 β-Caryophyllene 1000159- 39-0 0.07
      6 23.61 Desulfurized ketene 470-40-6 0.45
      7 23.797 Agarospirol 1460-73-7 1.08
      8 23.899 Patchoulene 1405-16-9 0.07
      9 24.23 Arctiol 36061-11- 7 0.38
      10 24.323 3,5,11-Dodecamethyltriene 193615- 07-5 0.06
      11 24.476 Guaiol 489-86-1 0.15
      12 24.697 Longipinocarvone 1000151- 87-1 0.31
      13 24.884 Caryophyllene 87-44-5 0.36
      14 26.056 Nerolidol 142-50-7 0.37
      15 26.252 β-Himachalene 116-04-1 0.12
      16 26.379 α-Cadinol 481-34-5 0.85
      17 27.203 Isolongifolol 1139-17-9 0.43
      18 27.704 Nootkatone 4674-50-4 5.63
      19 28.121 Arteannuin b 1000212- 12-6 0.9
      20 28.299 Isoshyobunone 1000360- 30-1 0.21
      21 29.183 Nerolidyl acetate 2306-78-7 0.38
      22 29.59 Himachalol II 19888-00- 7 0.78
      23 30.1 Bohlmann k2631 80367-94- 8 4.55
      24 30.372 Valerenic acid 609870 0.87
      25 30.482 Ambrosin 509-93-3 3.08
      26 31.434 Zederone 7727-79-9 0.68
      27 31.527 Spirafolide 130838- 06-1 0.36

      Table 2. 

      Twenty-seven sesquiterpene molecules.