LaMYC7, a positive regulator of linalool and caryophyllene biosynthesis, confers plant resistance to Pseudomonas syringae.

Linalool and caryophyllene are the main monoterpene and sesquiterpene compounds in lavender; however, the genes regulating their biosynthesis still remain many unknowns. Here, we identified LaMYC7, a positive regulator of linalool and caryophyllene biosynthesis, confers plant resistance to Pseudomonas syringae. LaMYC7 was highly expressed in glandular trichomes, and LaMYC7 overexpression could significantly increase the linalool and caryophyllene contents and reduce susceptibility to P. syringae in Nicotiana. In addition, the linalool possessed antimicrobial activity against P. syringae growth and acted dose-dependently. Further analysis demonstrated that LaMYC7 directly bound to the promoter region of LaTPS76, which encodes the terpene synthase (TPS) for caryophyllene biosynthesis, and that LaTPS76 was highly expressed in glandular trichomes. Notably, the LaMYC7 promoter contained hormone and stress-responsive regulatory elements and responded to various treatments, including ultraviolet, low temperature, salt, drought, methyl jasmonate, and P. syringae infection treatments. Under these treatments, the changes in the linalool and caryophyllene contents were similar to those in LaMYC7 transcript abundance. Based on the results, LaMYC7 could respond to P. syringae infection in addition to being involved in linalool and caryophyllene biosynthesis. Thus, the MYC transcription factor gene LaMYC7 can be used in the breeding of high-yielding linalool and caryophyllene lavender varieties with pathogen resistance.

Chemical Compositions of Essential Oil Extracted from Eight Thyme Species and Potential Biological Functions.

Thymus is an herbaceous perennial or subshrub of the Lamiaceae family and is widely distributed worldwide. Essential oils extracted from thymus have attracted much attention, owing to their potential biological functions. Here, we evaluated the chemical compositions of eight thyme essential oils (TEOs) using gas chromatography mass spectrometry and assessed their antioxidant activity. The results showed that (1) the main components in eight TEOs were monoterpene hydrocarbons and oxygenated monoterpenes (84.26-92.84%), and the chemical compositions of the TEOs were affected by the specie factor; (2) eight TEOs could be divided into three groups (thymol-, geraniol-, and nerol acetate-types), and thymol was the main type; (3) eight TEOs had some common compounds, such as thymol and p-cymene, which were the main components in seven TEOs; (4) eight TEOs had antioxidant activity, and Thymus pulegioides, Thymus thracicus, and Thymus serpyllum EOs had stronger antioxidant activity than vitamin E (0.07-0.27 fold) at a concentration of 1 mg/mL, while Thymus quinquecostatus and Thymus longicaulis EOs had relatively weak antioxidant activity. In addition, three chemical type standards were used to evaluate potential roles in antibacterial and tumor therapy. The results showed that thymol had strong antibacterial activity against the growth of Escherichia coli and Staphylococcus aureus, and antimigratory activity for A549 cell. Overall, our results can provide a theoretical basis for further exploring the function of natural products from thyme essential oils.

HybriDC: A Resource-Efficient CPU-FPGA Heterogeneous Acceleration System for Lossless Data Compression.

Lossless data compression is a crucial and computing-intensive application in data-centric scenarios. To reduce the CPU overhead, FPGA-based accelerators have been proposed to offload compression workloads. However, most existing schemes have the problem of an imbalanced resource utilization and a poor practicability. In this paper, we propose HybriDC, an adaptive resource-efficient CPU-FPGA heterogeneous acceleration system for lossless data compression. Leveraging complementary advantages of the heterogeneous architecture, HybriDC provides a universal end-to-end compression acceleration framework with application compatibility and performance scalability. To optimize the hardware compression kernel design, we build a performance-resource model of the compression algorithm taking into account the design goal, compression performance, available resources, etc. According to the deduced resource-balanced design principle, the compression algorithm parameters are fine-tuned, which reduces 32% of the block RAM usage of the LZ4 kernel. In the parallel compression kernel implementation, a memory-efficient parallel hash table with an extra checksum is proposed, which supports parallel processing and improves the compression ratio without extra memory. We develop an LZ4-based HybriDC system prototype and evaluate it in detail. Our LZ4 compression kernel achieves state-of-the-art memory efficiency, 2.5-4× better than existing designs with comparable compression ratios. The evaluation of total resource utilization and end-to-end throughput demonstrates the excellent scalability of HybriDC. In power efficiency, the four-kernel HybriDC prototype achieves a threefold advantage over the standard LZ4 algorithm.

The complete chloroplast genome of Cymbidium hookerianum (Orchidaceae): genome structure and basic analysis.

Cymbidium hookerianum Rchb.f. is an ornamental orchid with large flowers and delicate aroma. Here, we reported the complete chloroplast genome sequence of C. hookerianum. The total chloroplast genome cycle was 155,447 bp. It displayed a typical structure including one large single-copy (LSC, 84,186 bp) region, one small single-copy (SSC, 17,839 bp) region, and two inverted repeat (IRs, 26,711 bp). 124 genes (78 CDSs, 38 tRNAs, 8 rRNAs) were encoded by the cp genome. The average GC content of this sequence was 36.8%. The phylogenetic analysis revealed C. hookerianum and C. changningense are sisters. The groundwork of chloroplast genome would provide available reference for molecular taxonomy and breeding.

Chloroplast characterizations of a Phalaenopsis native to China, Phalaenopsis mannii (Orchidaceae).

Phalaenopsis mannii, one of the native Phalaenopsis in China, is an important parent for breeding new varieties. However, its position has been unclear in Phalaenopsis. The obtained high-quality P. mannii chloroplast genome will provide useful information for phylogenetic and future breeding of Phalaenopsis. Herein, we reported a complete chloroplast genome of P. mannii from Yunnan, China. The sequencing data obtained from BGISEQ-500 platform were assembled. This sequence had a circular molecular length of 148,596 bp and contained a total of 127 genes with an average GC content of 36.7%. Phylogenetic analysis indicated that Phalaenopsis was monophyletic with strong support, in which the P.mannii was the sister-group of Phalaenopsis aphrodite subsp. formosas, Phalaenopsis 'TinyStar' and Phalaenopsis equestris.

Chloroplast characterizations and phylogenetic location of a common ornamental cherry cultivar, Prunus campanulata 'Kanhizakura-plena' (Rosaceae).

Flowering cherries are well-grown in the world to develop a gorgeous landscape. Though several species are sequenced, there is huge mass of genome-level aberrances between wild species and highly domesticated cultivars. Herein, we established the complete chloroplast genome of Prunus campanulata 'Kanhizakura-plena'. The chloroplast genome circle (157948 bp) was formed by an 85949 bp large single-copy (LSC) region, a 19127 bp small single-copy (SSC) region, and 2 inverted repeat (IRs) regions of 26436 bp. Independent annotation showed 124 genes were found and conserved tRNA genes and rRNA genes were 37 and 8, respectively. The overall GC content was 36.72%, same with the known species, P. campanulata. Phylogenetic tree confirmed the relationship that P. campanulata 'Kanhizakura-plena' is most closely related to P. campanulata, nested inside Prunus. This announcement of chloroplast genome helps genetic modification and phylogenetic study in Prunus genus with useful information. It is a valuable resource for further breeding.

Basic chloroplast characterizations of Prunus campanulata x kanzakura 'praecox', a warm-adapted cherry cultivar in South China (Rosaceae).

Flowering cherries are domesticated to cultivars by multiple hybridization from some original species, and there formed various adaptive abilities. Herein, we established the complete chloroplast genome of Prunus campanulata x kanzakura 'Praecox'. The chloroplast genome circle (157,917 bp) presented a typical structure of one 85,928 bp LSC, one 19,117 bp SSC region, and two 26,436 bp IRs. It encoded 124 genes, and same conserved tRNA genes and rRNA genes with P. campanulata, 37 and 8, respectively. The overall GC content was 36.72%. Phylogenetic analysis confirmed the maternal inheritance relationship that P. campanulata x kanzakura 'Praecox' comes from Prunus campanulate with little chloroplast genome change, nested inside subgenus Cerasus. This announcement of chloroplast genome would provide helps in further genetic modification and distinction mark study in Prunus genus.