Project description:BACKGROUND:Dalbergia odorifera T. Chen (Fabaceae) is an International Union for Conservation of Nature red-listed tree. This tree is of high medicinal and commercial value owing to its officinal, insect-proof, durable heartwood. However, there is a lack of genome reference, which has hindered development of studies on the heartwood formation. FINDINGS:We presented the first chromosome-scale genome assembly of D. odorifera obtained on the basis of Illumina paired-end sequencing, Pacific Biosciences single-molecule real-time sequencing, 10x Genomics linked reads, and Hi-C technology. We assembled 97.68% of the 653.45 Mb D. odorifera genome with scaffold N50 and contig sizes of 56.16 and 5.92 Mb, respectively. Ten super-scaffolds corresponding to the 10 chromosomes were assembled, with the longest scaffold reaching 79.61 Mb. Repetitive elements account for 54.17% of the genome, and 30,310 protein-coding genes were predicted from the genome, of which ?92.6% were functionally annotated. The phylogenetic tree showed that D. odorifera diverged from the ancestor of Arabidopsis thaliana and Populus trichocarpa and then separated from Glycine max and Cajanus cajan. CONCLUSIONS:We sequence and reveal the first chromosome-level de novo genome of D. odorifera. These studies provide valuable genomic resources for the research of heartwood formation in D. odorifera and other timber trees. The high-quality assembled genome can also be used as reference for comparative genomics analysis and future population genetic studies of D. odorifera.
Project description:Dalbergia odorifera T. Chen is a medium-sized evergreen tree that produces purple-brown heartwood called JiangXiang in traditional Chinese medicine, the formation process of which takes several decades. In this study, a standard culture method was used to isolate fungi from the wounded and normal stems of D. odorifera aiming to investigate the difference between the two types of wood. To characterize the spatial colonisation of endophytic fungi, an anatomical study was undertaken using the two different types of wood of D. odorifera. A total of 320 wood segments were placed on PDA plates and 87 fungal isolates were obtained. Only two fungi were isolated from the healthy white wood tissue, whereas 85 fungi were found in the purple-brown wounded-wood tissues. The two isolates from 160 white healthy wood tissues were assigned to Bionectriaceae sp., and the rest in wounded wood tissues were analyzed to 12 fungal species, indicating both a high fungal diversity and colonization rate in the purple-brown wounded wood. There was a difference in fungal species composition between coloured and white wood samples collected from the same tree. Eutypa sp. was the most commonly isolated species in the purple-brown wounded wood.
Project description:Salinity is one of the most serious factors limiting plant growth which can provoke significant losses in agricultural crop production, particularly in arid and semi-arid areas. This study aimed to investigate whether melatonin (MT; 0.05 and 0.1 mM), which has pleiotropic roles, has a better effect than glycine betaine (GB; 10 and 50 mM) on providing salt tolerance in a woody plant Dalbergia odorifera T. Chen. Also, the alternative oxidase activity (AOX) in plant subjected to MT or GB under salinity (150 and 250 mM) was evaluated given that the effect of exogenous MT or GB on AOX has not been reported yet. The results showed that the exogenous application of GB on the seedlings of D. odorifera increased the plant growth parameters, relative water content, total of chlorophyll content, and carotenoid content compared with well-watered and MT treatments. Under severe salinity, the seedlings subjected to GB showed, a significant enhancement in water use efficiency, transpiration, and net photosynthetic rate regardless to MT-treated seedlings. The levels of proline and soluble sugar in the seedlings treated with MT or GB decreased significantly under mild and severe salinity correlated with those in salt-stressed seedlings. Furthermore, GB-treated plants exhibited a significant inhibition of malondialdehyde content compared with MT-treated plants. The concentration of thiols and phenolic compounds were significantly enhanced in the leaves of seedlings treated with MT compared with those treated with GB. Under salt stress condition, GB scavenged significantly higher levels of hydrogen peroxide than MT; while under severe salinity, plants subjected to MT showed better scavenging ability for hydroxyl radicals compared with GB-treated seedlings. The results demonstrated also an enhancement of the levels of superoxide dismutase (SOD), guaiacol peroxidase, and AOX activities in seedlings treated with GB or MT compared with salt-stressed plants. The catalase activity (CAT) was increased by 0.05 mM MT and 0.1 mM GB under mild salinity. Meanwhile, the AOX activity under severe salinity was enhanced only by GB 50 mM. The findings of this study suggested that GB-treated seedlings possessed a better salt tolerance in comparison with MT-treated seedlings.