An orthogonal experiment (three factors × three levels) was designed to establish a cutting propagation technique for Hevea brasiliensis rootstock seedlings. The effects of substrate, exogenous hormone type, and concentration on rooting were evaluated across nine treatments. Rooting rate, four root traits, and mineral element contents were measured, and rooting performance was comprehensively assessed using the membership function method. Substrate was found to be the dominant factor, significantly affecting rooting rate, total root length, primary root number, and K, Ca, Mg, Fe, and Zn contents. Neither hormone type (IAA, IBA, NAA) nor concentration (100–500 mg/L) exhibited significant effects on rooting. The soil yielded the highest mean membership value, with the soil + 500 mg/L IAA treatment ranking first (0.984). Overall, the highest rooting rate and root traits were obtained with soil and 500 mg/L IAA, which is recommended as the optimal protocol for rooting of rubber tree seedling cuttings.

The Dalbergia genus, a morphologically diverse group within the Fabaceae family, encompasses species of significant value in furniture production and medicinal and aromatic applications. The taxonomy of Dalbergia has relied on morphological traits, chloroplast (cp) DNA fragments, and cp genomic data. However, genomic resources for tropical liana species within this genus remain scarce. In this study, we assembled and analyzed the cp genomes of 3 liana species—Dalbergia peishaensis, D. pinnata, and D. tsoi—and compared them with those of 26 other Dalbergia species to explore their cp genome characteristics and evolutionary patterns. We employed a combination of traditional cp genome analysis and methods adapted from plant whole-genome sequencing. Phylogenetic analysis revealed that D. peishaensis has a close relationship with D. cultrata, forming a recently diverged clade, whereas D. tsoi and D. pinnata are positioned within a basal clade of the Dalbergia genus, suggesting an earlier divergence. The Dalbergia cp genomes exhibit considerable variation in size, with evidence of pseudogenization, gene loss, and duplication observed in the three liana species. Notably, the infA gene, previously reported as absent in the chloroplast genomes of Dalbergia species, was identified in the cp genomes of these three liana Dalbergia species. A total of 4533 simple sequence repeats (SSRs) were identified, providing valuable insights into cp genome evolution and facilitating future population genetics studies, particularly when combined with the high structural variation observed in the genus through whole-genome analysis methods. Additionally, seven highly divergent regions were identified as potential DNA barcode hotspots. This study enhances the genomic characterization of liana Dalbergia species and offers a robust framework for future plant cp genome analyses by integrating methodologies originally developed for whole-genome studies.

D-arginine (D-Arg) can promote embryogenic callus (EC) proliferation and increase the rate of somatic embryo induction of litchi (Litchi chinensis Sonn.), yet the mechanism underlying the processes is incompletely understood. To investigate the mechanism, physiological responses of polyamines (PAs) [putrescine (Put), spermidine (Spd), and spermine (Spm)] were investigated for D-Arg-treated litchi EC and enzyme activity related to polyamine metabolism, plant endogenous hormones, and polyamine- and embryogenic-related genes were explored. Results showed that the exogenous addition of D-Arg reduces the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) in EC, reduces the production of H2O2, promotes EC proliferation, and increases the (Spd + Spm)/Put ratio to promote somatic embryo induction. Exogenous D-Arg application promoted somatic embryogenesis (SE) by increasing indole-3-acetyl glycine (IAA-Gly), kinetin-9-glucoside (K9G), and dihydrozeatin-7-glucoside (DHZ7G) levels and decreasing trans-zeatin riboside (tZR), N-[(-)-jasmonoyl]-(L)-valine (JA-Val), jasmonic acid (JA), and jasmonoyl-L-isoleucine (Ja-ILE) levels on 18 d, as well as promoting cell division and differentiation. The application of exogenous D-Arg regulated EC proliferation and somatic embryo induction by altering gene expression levels of the WRKY family, AP2/ERF family, C3H family, and C2H2 family. These results indicate that exogenous D-Arg could regulate the proliferation of EC and the SE induction of litchi by changing the biosynthesis of PAs through the alteration of gene expression pattern and endogenous hormone metabolism.

An in-depth study of the phylogenetic relationships of Xylaria species associated with nutshells of fruits and seeds within the genus Xylaria and related genera of Xylaceaecea was conducted in China. The multi-gene phylogenetic analyses were carried out based on ITS, RPB2, and TUB sequences of 100 species of 16 known genera in Xylariaceae around the world. Based on molecular phylogenetic analyses, morphological observations, and ecological habitats, a new genus, Heteroxylaria, is established to accommodate four new species, viz. H. cordiicola, H. juglandicola, H. meliicola, and H. terminaliicola, and four new combinations, viz. H. oxyacanthae, H. palmicola, H. reevesiae, and H. rohrensis. The genus is characterized by cylindrical stromata with conspicuous to inconspicuous perithecial mounds, surface black, having brown to dark brown ascospores with a germ slit, and it grows on nutshell of fruits. The combined ITS+RPB2+TUB sequence dataset of representative taxa in the Xylariaceae demonstrate that Heteroxylaria is grouped with Hypocreodendron but forms a monophyletic lineage. All novelties described herein are morphologically illustrated and compared to similar species and phylogeny is investigated to establish new genera and species.

Anthocyanidin reductase (ANR) is a key enzyme regulating anthocyanin synthesis and accumulation in plants. Here, lychee ANR genes were globally identified, their sequence and phylogenetic characteristics were analyzed, and their spatiotemporal expression patterns were characterized. A total of 51 ANR family members were identified in the lychee genome. The length of the encoded amino acid residues ranged from 87 aa to 289 aa, the molecular weight ranged from 9.49 KD to 32.40 KD, and the isoelectric point (pI) ranged from 4.83 to 9.33. Most of the members were acidic proteins. Most members of the LcANR family were located in the cytoplasm. The 51 LcANR family members were unevenly distributed in 11 chromosomes, and their exons and motif conserved structures were significantly different from each other. Promoters in over 90% of LcANR members contained anaerobically induced response elements, and 88% contained photoresponsive elements. Most LcANR family members had low expression in nine lychee tissues and organs (root, young leaf, bud, female flower, male flower, pericarp, pulp, seed, and calli), and some members showed tissue-specific expression patterns. The expression of one gene, LITCHI029356.m1, decreased with the increase of anthocyanin accumulation in ‘Feizixiao’ and ‘Ziniangxi’ pericarp, which was negatively correlated with pericarp coloring. The identified LcANR gene was heterologously expressed in tobacco K326, and the function of the LcANR gene was verified. This study provides a basis for the further study of LcANR function, particularly the role in lychee pericarp coloration.

Hypoxylaceous fungi are abundant in China, but their discovery and report are uneven in various provinces, with more fungi in Yunnan and Hainan and fewer fungi in Tibet. During the investigation of macro-fungi in Motuo county, Tibet Autonomous Region, we collected a number of xylarialean specimens. Six hypoxylaceous specimens growing on dead angiosperm were collected from the forests of Motuo county, and they were described and illustrated as two new species in Hypoxylon based on a combination of morphological characters and molecular evidence. Hypoxylon diperithecium was characterized by its bistratal perithecia, purple-brown stromatal granules, citrine to rust KOH-extractable pigments, and light brown to brown ascospores ellipsoid-inequilateral with conspicuous coil-like ornamentation. Hypoxylon tibeticum was distinct from other species by having pulvinate and applanate stromata, surface vinaceous, with orange granules, orange KOH-extractable pigments, and brown ascospores with inconspicuous ornamentation. The multi-gene phylogenetic analyses (ITS-LSU-RPB2-TUB) supported the two new taxa as separate lineages in the genus Hypoxylon. A key to all known Hypoxylon taxa from China is provided.

Scaevola taccada (Goodeniaceae) is an important evergreen coastal plant on islands in the South China Sea, which shows excellent tolerance for salty and drought conditions. Nevertheless, the growth of S. taccada populations on these islands in the South China Sea has been threatened by a few serious insect pests. However, we know little about the biology of these pests. In this study, we surveyed and identified the parasitoids of two main pests (Herpetogramma submarginale (Swinhoe, 1901) and Ophiomyia scaevolana Shiao and Wu, 1996) of S. taccada communities on Yongxing Island in the South China Sea, with the aim to assess their potential in biological control. Dolichogenidea stantoni (Ashmead, 1904) is a gregarious endoparasitoid of the larva of H. submarginale and contributes an average 48.9% parasitism rate on H. submarginale. Opius biroi, Fischer, 1960 and Euderus albitarsis (Zetterstedt, 1838) are both solitary endoparasitoids of the larva of O. scaevolana, with a respective 5.8% and 64.4% parasitism rate on O. scaevolana. We summarize the species diagnosis, biology, and distribution of the three parasitoid species. The potential of these parasitoids used in biological control is also discussed.

Morphological and phylogenetic analyses on samples of Xylaria species associated with fallen fruits from China were carried out, and two new species were described, namely X. aleuriticola and X. microcarpa. Xylaria aleuriticola is found on fallen fruits of Aleurites moluccana, and characterized by stromata dichotomously branched several times with long acute sterile apices, fertile parts roughened with perithecia and tomentose, and ellipsoid to fusiform ascospores. Xylaria microcarpa differs in its very small stromata with dark brown tomentum, light brown ascospores with an inconspicuous straight germ slit, and grows on leguminous pods. The differences between the new species and morphologically similar species are discussed. Phylogenetic analyses on ITS-RPB2-TUB sequences confirmed that the two species are clearly separated from other species of the genus Xylaria. Xylaria liquidambaris is reported as a new record from China. A key to the Xylaria species associated with fallen fruits and seeds reported from China is provided to facilitate future studies of the genus.

The current study explored the effects of low root-zone temperature (LT) and UV radiation (UV) alone and combined on changes in growth, transcription, and gene expression related to secondary metabolite production. Nicotiana benthamiana plants were grown in a controlled environment (25/20°C, 16/8 h [light/dark], 70% relative humidity, 1,000 µmol·mol−1 CO2 with photosynthetic photon flux densities of 100 and 200 µmol·m−2·s−1 for 10 and 18 d, respectively). Twenty-eight days after sowing, these plants were treated with LT (15°C), 0.3 W·m−2 of UV radiation, and a combined treatment with LT and UV (LT*UV) for 3 d. Results found that the treatment with UV alone decreased the quantum efficiency of photosystem II by approximately 1.5 times, and most growth characteristics decreased under the UV (approximately 1.5 times) and LT*UV (approximately 2 times) treatments. Treatment with LT*UV significantly inhibited the growth characteristics and photosynthetic rates compared to those under the single LT and UV treatments. Changes in the transcriptome of plants in response to different environmental conditions were determined based on the expression levels of genes related to secondary metabolites and microarrays. In particular, the transcriptome levels of phenylpropanoid and flavonoid biosynthesis were the most significantly affected by LT*UV. This suggests the potential of using LT treatment in hydroponic systems and UV radiation to control the synthesis of health-promoting compounds of secondary metabolites in greenhouses and controlled-environment agricultural facilities.

本研究分别采用GB/T 1933-2009《木材基本密度测定方法》、GB/T 6043-2009《木材pH的测定》、蒽酮比色法、考马斯亮蓝法、木材解剖学方法和气相色谱-质谱(GC-MS)法测定了马达加斯加特有种茶鹃木(Humbertia madagascariensis Lam.)的木材(又称"药香黄檀")的基本密度、pH、淀粉含量、可溶性蛋白含量、解剖结构及挥发性成分,为茶鹃木木材识别、植物保育及加工利用等研究提供依据.研究表明:茶鹃木木材的基本密度为 1.684 g/cm3,水试发现其沉水.茶鹃木木材的 pH 为 6.78,淀粉含量为 10.953 mg/g,可溶性蛋白含量为 0.271 mg/g.茶鹃木木材的宏观构造:黄褐色,木材有光泽;有"柑橘檀香"味,散孔材,管孔较大;管孔内、边缘含有白色至金黄色侵填体,弦切面上特别明显;横切面上射线清晰,均匀细密;径切面上射线斑纹明显,分布密集;弦切面上呈细线状,波痕略可见.微观构造:管孔为椭圆形、圆形,数目为 3～5 个/mm2;单管孔,分散,管孔内、边缘含有金黄色树胶;木射线非叠生,同形,单列,7～9 根/mm;射线细胞较大,多数为椭圆形、长圆形,通常不含有树胶;横卧射线方形细胞 3～7层;三切面上导管外侧及纤维组织中椭圆状晶体明显,数量众多,纵向排列规则.GC-MS分析表明:其主要成分为脂肪酸类(88.81%),其次为脂类(8.12%)和萜烯类(0.94%),其中含量最高的化合物为棕榈酸(47.32%),其次为硬脂酸(38.79%),另外,还含有少量的不饱和脂肪酸,如亚油酸(0.23%)和油酸(0.61%),推测茶鹃木木材的"柑橘檀香"味可能与此挥发性成分有关.

Hevea brasiliensis is an important economic crop which produces natural rubber. Supplemental LED night lighting improves its growth, however the underlying molecular mechanism remains unknown. The study analyzed the transcriptome of H. brasiliensis plants under the treatment of LED night lighting. The light treatment resulted in 1047 and 411 differentially expression genes (DEGs) during the day and night time, respectively. Functional group analysis showed that DEGs in the day time enriched into 185 metabolic pathways and that DEGs in the night time enriched into 116 metabolic pathways. A total of 92 DEGs were identified between night lighting and control plants. These DEGs were involved in regulation of pigment metabolism, photosynthesis, circadian rhythm, and carbohydrate metabolism. The genes associated with circadian rhythm were altered during the day and night time. The gene involved in carbohydrate metabolic process was upregulated and the related KEGG pathways associated carbohydrate metabolism were upregulated. These results concluded that supplemental LED night lighting improve growth of hevea plants by upregulating genes associated with photosynthesis and carbohydrate metabolism, so as to synthesize more carbohydrates.

Postharvest pericarp browning restricts the shelf life of litchi fruit and was considered as the main bottleneck of litchi industry. Browning is mainly due to the enzymatic catalysis of phenols to form brown substances in the litchi pericarp. (-)-Epicatechin, (-)-gallocatechin, and procyanidin B2 are the main substrates for enzyme catalysis. Previous works have reported that laccase activity was correlated with pericarp browning, and laccase polymerizes substrates in vitro, but the direct evidence was absent. In this research, the sequence of laccase gene LcLac was analyzed, whose expression was correlated with browning index of litchi pericarp at postharvest. Overexpression of LcLac in callus led to higher gene expression and enzymatic activity, and a lower polyphenol content, which contributed to browning of callus. Contrarily, the LcLac gene blocked by CRISPR/Cas9 resulted in an opposite trend of polyphenol contents. LcLac overexpression promoted callus browning, and the gene target block delayed the browning phenomenon. The results clearly indicate that LcLac can be polymerized with polyphenols and is involved in callus browning. LcLac may also participate in polyphenol synthesis and maintain the polyphenol balance in vacuoles.

Fusarium oxysporum f. sp. cubense (Foc) causes banana Fusarium wilt disease, which is a destructive soil-borne disease. Many plants can recruit rhizosphere microorganisms using their root exudates, thereby shaping the rhizosphere microbiome to resist pathogen infection. Therefore, this study was conducted to explore the role of root exudates in the process of biocontrol strain colonization and resistance to pathogens. In this study, the banana root exudates used as chemoattractants were obtained by hydroponics. Bacillus velezensis strain LG14-3 was isolated from the infected area of the root system of banana and showed significant chemotaxis to banana root exudates and strong inhibition of Fusarium oxysporum f. sp. cubense. Further analysis found that LG14-3 showed chemotaxis toward the components of banana root exudates, such as citric acid, succinic acid, glycine, D-galactose and D-maltose, and glycine and citric acid, which resulted in more significant chemotaxis of LG14-3. Moreover, banana root exudates enhanced the swarming motility and biofilm formation of LG14-3. Pot experiments showed that glycine and citric acid enhanced the colonization ability of Bacillus velezensis LG14-3 in the banana rhizosphere and reduced the disease severity index of banana fusarium wilt. Glycine and citric acid enhanced the growth-promoting ability of LG14-3 under pathogen stress. Our results showed that the addition of chemotactic substances enhanced the biocontrol potential of Bacillus velezensis LG14-3 to prevent banana Fusarium wilt.

Six different germplasms of Aquilaria sinesis（Lour.） Spreng.（three approved improved varieties: Haixiang 1,Haixiang 2 and Haixiang 3, and three pre-varieties: Piyou type, Big leaf type and Nangpao type） were used as the research objects. Among them, Piyou type came from Jieyang city, Guangdong province, Big leaf type species came from Ding’an county, Hainan province, and the rest came from Wenchang city, Hainan province. The pH, starch content,soluble sugar content, soluble protein content and cellulose content of the wood from trunk were determined by GB/T6043—2009（Determination of wood pH）, anthrone colorimetric method, Coomassie bright blue method and nitric acid-ethanol method respectively. SPSS 26.0 was used to conduct variance analysis, multiple comparison analysis（Waller-Duncan method, LSD method） and Pearson correlation analysis on the measurement results of the above five indicators. The test results indicated that the wood from the trunk of six different A. sinensis germplasms were acidic,and the pH ranged from 5.40 to 6.06. The pH of the trunk was the highest in Haixiang 3 and the lowest in Big leaf type.The starch content ranged from 13.16 to 33.85 mg/g. Among them, the trunk starch content of Big leaf type was the highest, and that of Haixiang 3 was the lowest. The soluble sugar content ranged from 3.60 to 20.16 mg/g. Among them,the trunk soluble sugar content of Big leaf type was the highest, and that of Haixiang 1 was the lowest. The soluble protein content ranged from 0.17 to 0.25 mg/g. Among them, the trunk soluble protein content of Haixiang 1 was the highest, and that of Piyou type was the lowest. The cellulose content ranged from 0.46 to 0.61 g/g. Among them, the trunk cellulose content of Haixiang 1 was the highest, and that of of Haixiang 2 was the lowest. The analysis results indicated that there were significant differences in pH, starch content, soluble sugar and cellulose content among different A. sinensis germplasms（P＜0.05）, but no significant differences in soluble protein content. There was a very significant negative correlation between pH and soluble sugar content, starch content（P＜0.01）. There was a very significant positive correlation between starch content and soluble sugar content（P＜0.01）. The content of soluble protein and cellulose content had no significant correlation with other physiological traits. This study could provide basic data for varieties breeding, upgrading and adjustment of planting industrial structure, DUS test guidelines and so on.

本研究旨在根据空气控根原理探讨培育高质量橡胶树大筒苗的最佳悬空高度.以芽接桩为胚苗材料,比较不同育苗筒悬空高度对橡胶树大筒苗生长发育及壮苗指数的影响.结果表明:橡胶树大筒苗生长至6蓬叶物候稳定时,株高、茎粗、总鲜重及壮苗指数均随着筒底悬空高度的降低而逐渐增大,以悬空的T1～T3(+12～+4 cm)和触地T4(0 cm)及埋地T5(-4 cm)为分界点,穿根率、穿出筒底的主根粗度、叶蓬数、总叶片数、出圃率、定植成活率等均显著增加;触地T4(0 cm)及埋地T5(-4 cm)的大筒苗株高比悬空的T1～T3高约20～25 cm,多生长1蓬叶,叶片数多16～19片,出圃率提高15％～20％,定植成活率提高10％～15％;壮苗指数以T5最高,达68.57,其次是T4(48.77),约是T1～T3的3～4倍;橡胶树大筒苗的综合排名以埋地的T5(-4 cm)的隶属度平均值最高(0.79),触地的T4(0 cm)其次(0.72),悬空的T2(+8 cm)最低(0.24).因此,今后培育橡胶树大筒苗若想获得较好的生长势和育苗效果,建议触地或埋地培养;若以空气控根为目的培育大筒苗,建议筒底悬空高度以8 cm以上为宜.

长期实践证明:化学防治农作物害虫会带来药物残留且会对环境造成不同程度的污染,而生物防治效果更为环保、安全.虫生真菌作为生物防治的重要手段可以在保护原有生态环境的基础上采用一定生物手段合理防控害虫,不仅能促进农业生产的可持续发展,同时保障了我国食品绿色、安全,近年来在防治农作物害虫上发挥了出色的作用.本文分别介绍虫生真菌代表种:白僵菌、绿僵菌、拟青霉、轮枝菌等菌落特征及防治对象,从致病机理和毒力进行综合阐述,并围绕了真菌制剂产品特点、产品创制以及开放利用,系统总结虫生真菌在我国农业生产中的应用进展,旨在为我国的生态安全以及虫生真菌的开发及应用提供参考.

Phenology can directly reflect the characteristics of rubber seedling, people can determine the agricultural time arrangements of seedling germination, cut back, tending management and nursery operation. In this study, the phenological period of the top leaf of hevea tree seedlings was divided into four treatments, and cut back was carried out in sprout period, bronze stage, light green stage and stable stage, respectively. The effects of sawing stock in different phenological periods on the budding rate and growth potential of scion 1-2 were observed. The results showed that the budding rate and nursery rate of scion were significantly higher than those of other stages when the leaf phenology stage was sawed in sprout stage and stable stage, and the budding rate and nursery rate were the lowest in the light green stage. In the first leaf whorl, the plant height of stock leaf phenology stage was significantly higher in sprout stage and bronze stage than in light green stage, but there was no significant difference with stable stage; The stem diameter of stable phenological stage was significantly larger than that of bronze and light green phenological stage, but there was no significant difference with that of sprout stage; The leaf whorl distance in the paleobronze period was significantly higher than that in the light green period, but there was no significant difference with other periods; The number of leaves in phenological stage was significantly more in sprout stage than in light green stage, and there was no significant difference from other stages. In the second leaf whorl, The plant height, stem diameter, leaf distance and leaf number of scion of stock seedlings in phenology stage were significantly higher than those in other stages, and the growth of stock seedlings in light green stage was lowest. In conclusion, the leaf phenology stage of the rootstock seedlings of rubber tree is in the sprout stage, and the scion growth is the best, followed by the stable stage and bronze stage. Cut back in the light green stage is not recommended.

比较3个白木香良种'热科1号'(Aquilaria sinensis' Reke 1')、'热科2号'(A.sinensis' Reke 2')、'热科3号'(A.sinensis' Reke 3')及国外引种的印度沉香(A.agallocha Roxb.)植物叶片挥发油成分的异同,旨在为其进一步开发利用提供依据.采用水蒸气蒸馏法提取4种叶片中的挥发油,用气相色谱-质谱联用(GC-MS)技术对其成分进行分析获得总离子流图,通过Date Analysis化学工作站,结合Nist2005和Wiley275质谱库及前人鉴定方法等对检测到的色谱峰进行检索及人工解析;利用峰面积归一化法测定其化学成分的相对百分含量,统计数据后进行对比分析.结果 表明,3个白木香良种与印度沉香叶片挥发油仅5个共有成分,独有成分数量较多占半数以上;'热科1号'(34.44％)、'热科3号'(25.08％)及印度沉香(37.06％)叶片挥发油中萜类总相对百分含量较高,'热科2号'(13.20％)中相对较低,其中'热科1号'(9.82％)与'热科2号'(8.17％)沉香叶挥发油中分别有3种、8种倍半萜类化合物且均为独有;'热科2号'(5.03％)沉香叶挥发油中二萜类成分远低于其他三者('热科1号'为19.25％、'热科3号'为24.18％、印度沉香为35.45％);'热科1号'(5.37％)与印度沉香(1.61％)叶片挥发油中含三萜类成分,其他二者未检出.综上,萜类多具有抗菌抗炎活性,故'热科1号''热科3号'及印度沉香叶片挥发油更适合发掘其在药用、保健方面的功能,印度沉香叶挥发油的二萜类化合物中致香成分含量较高,适合发掘香料、烟草等方面的应用价值,'热科2号'叶挥发油具有苦味的二萜类化合物含量低,在食品、茶饮方面具有较好的开发潜能及应用前景.因此,对不同沉香树叶及挥发油的开发利用应更具针对性,充分挖掘其价值,开发高附加值产品并推动沉香树种植产业调整升级,促进沉香产业发展.

为探究不同栽培奇楠树所结沉香的显微结构特征,收集15份栽培奇楠树所结沉香样品,通过木材切片和显微观察的方法进行解剖学研究,对其三切面的显微结构特征进行观测、描述、统计、对比和分析,并与普通白木香所结沉香进行对比.结果表明,栽培奇楠树所结沉香样品在显微结构方面有共性特征,其树脂均主要分布于内涵韧皮部、木射线及导管中,树脂丰富且有向木纤维扩散的趋势,在千里香中表现明显,而与之相比,普通白木香所结沉香样品中树脂主要集中于导管中且含量较少,二者差异较大,就树脂富集面积与含量而言,栽培奇楠树所结沉香样品明显优于普通白木香所结沉香样品;此外,部分栽培奇楠所结沉香样品内涵韧皮部与髓心中可见大量草酸钙棱晶,晶体作为树木抵御外界伤害的一种方式,推测其有利于奇楠树受到创伤开始结香后结香面积的扩展与树脂含量的增加;对沉香样品部分特征的定量数据进行统计研究,结果表明部分栽培奇楠树所结沉香样品间有较大差别,如金丝油的管孔密度、直径,内涵韧皮部宽度、密度,射线宽度、间距等与其他样品差异较大,聚类分析结果表明,栽培奇楠树所结沉香金丝油与乌身圆叶较为特殊,位于分支树的根部,千里香、张勺子、透顶绿及凹身木聚为一类,其余9个样品绿油王、'热科2号'、樱桃叶、糖结、紫棋、蓝宝石、西瓜叶、指天椒及油叶子聚为一类.本研究可为栽培奇楠的树种选育、资源利用、检测鉴定和市场规范化提供依据,尽快完善相关研究才能不断推进沉香产业良性发展.

Coriander (Coriandrum sativum) is a medicinal and aromatic plant. From November 2017 to March 2020, leaf blight disease on coriander plants was frequently observed in commercial coriander cultivated fields of Haikou, Sanya and Wanning City, Hainan Province, China. Leaves with symptoms showed irregular chlorotic to dark brown necrotic lesions at the edges of leaves, and the leaves were curled and covered with a layer of grey mould. Based on morphological characteristics, pathogenicity testing and concatenated sequences of the internal transcribed spacer region (ITS), actin (ACT) and translation elongation factor-1 alpha (TEF) genes, the pathogen was identified as Cladosporium tenuissimum. Untargeted metabolomes of the coriander leaves were analysed by gas chromatography-mass spectrometry (GC-MS). Score plots of principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) showed clear discrimination between infected and control treatments. The levels of l-threonic acid, hexadecanoic acid and myo-inositol in the control treatment were 3.45-, 1.81- and 2.44-fold, respectively, those in the infected treatment. To our knowledge, this is the first report of C. tenuissimum causing coriander leaf blight disease in China. Furthermore, this study indicates that C. tenuissimum infection of coriander causes a significant decrease in l-threonic acid, hexadecanoic acid and myo-inositol levels, indicating that these metabolites may be involved in the plant's response to coriander leaf blight disease.