RT-qPCR analysis of CymMV and ORSV RNA in protoplasts of WT and transgenic lines after C+O infection at 18 hpi. Values are normalized against CymMV and ORSV RNA in protoplasts of WT plants infected with C+O.

The Orchidaceae is the largest and most diverse family of flowering plants. Because of the fascinating array of colors, delicate flower shapes, and fragrant blooms, orchids have become popular and valuable ornamental plants in the market. Taxonomically distinct Cymbidium mosaic potexvirus (CymMV) and Odontoglossum ringspot tobamovirus (ORSV) are two of the most prevalent viruses worldwide; when co-infecting orchids, they cause synergistic symptoms. Because of the huge economic loss in quality and quantity in the orchid industry with virus-infected orchids, virus-resistant orchids are urgently needed. To date, no transgenic resistant lines against these two viruses have been reported. Dr. Na-Sheng Lin’s group generated transgenic Nicotiana benthamiana expressing various constructs of partial CymMV and ORSV genomes. Several transgenic lines grew normally and remained symptomless after mixed inoculation with CymMV and ORSV. The replication of CymMV and ORSV was approximately 70% - 90% lower in protoplasts of transgenic lines than wild-type (WT) plants. Of note, extremely low or no viral RNA or capsid protein of CymMV and ORSV was detected in systemic leaves of transgenic lines after co-infection. Grafting experiments further revealed that CymMV and ORSV trafficked extremely inefficiently from co-infected WT stocks to transgenic scions, presumably due to RNA-mediated interference. This study reports the first successful creation of dual resistant transgenic lines against CymMV and ORSV and shed light on the commercial development of transgenic orchid production to combat the global viral threat. The article was reported in “Scientific Reports. 2019. 9:10230.” https://doi.org/10.1038/s41598-019-46695-7.

A research team led by Dr. Nakamura discovered that NPC2 and NPC6, a pair of bacterial toxin-like phospholipases C found only in bacteria and seed plants, produce phosphocholine (PCho) from membrane phospholipids to promote root growth in Arabidopsis thaliana. PCho is an emerging root growth-promoting factor, which is produced by methyltransferase activity. Thus, our results reveal a new pathway for PCho production catalyzed by the NPCs, highlighting a “non-toxic” role of a “toxic” enzyme activity. The results may contribute to the understanding of root growth, an important agronomic trait.

Web link to publication

https://onlinelibrary.wiley.com/doi/10.1111/tpj.14494

Lab Name : Proteomics Core Lab, Institute of Plant and Microbial Biology, Academia Sinica, Taiwan

Job Position : Specialist

Recruitment information : https://ipmb.sinica.edu.tw/ch/recruitment/28

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Transformation technology is of fundamental importance in modern genetics both for basic research and biotechnology applications. Among the tools available, Agrobacterium-mediated transformation has several advantages over other alternatives. However, the hosts that could be transformed effectively are limited and such limitation may have been resulted from the strong research focus on a single model Agrobacterium strain (i.e., C58). To address this issue, this study compared the genome and transcriptome of C58 to 1D1609 (i.e., a wild-type strain that differs in host range) with the goal of identifying the genes that may explain their phenotypic differences. The results reveal extensive variation in gene content and expression regulation, as well as provided a short list of candidate genes for molecular characterization.

This work was done by collaboration between Chih-Horng Kuo and Erh-Min Lai. The authors include two research assistants in the Kuo lab (Mindia Haryono and Shu-Ting Cho), and the team members of the Genomic Technology Core of IPMB (Mei-Jane Fang, Ai-Ping Chen, and Shu-Jen Chou).

Haryono M, Cho ST, Fang MJ, Chen AP, Chou SJ, Lai EM, Kuo CH* (2019) Differentiations in gene content and expression response to virulence induction between two Agrobacterium strains. Frontiers in Microbiology 10: 1554. DOI: 10.3389/fmicb.2019.01554

This month’s special issue of Plant Cell Physiology puts a spotlight on iron nutrition and interactions in plants, and includes a meeting report of the 19th International Symposium on Iron Nutrition and Interactions in Plants (ISINIP), by organizing editor Wolfgang Schmidt, and four review articles covering different aspects of iron nutrition, including sensing, transport and signaling; biofortification; and soil processes.

The cover shows cross-sections of a wheat grain (Triticum aestivum) (bottom left) and common bean seed (Phaseolus vulgaris) (bottom right) stained for iron with Perls' staining (blue) to show the fundamentally different distribution of iron in these two seed-types. Sample preparation was performed by James Connorton (John Innes Centre, UK) and Mashamba Philipo (NM AIST, Arusha, Tanzania), while images were taken by Phil Robinson and Janneke Balk (John Innes Centre, UK), respectively. Also shown on the cover is the visualization of fluorescent coumarins produced by roots of an Fe-starved Arabidopsis thaliana Col-0 plant pictured above the basic coumarin chemical structure (right panel); image supplied by Ioannis Stringlis (Utrecht University, the Netherlands). Finally, the top right corner features the 19^th ISINIP conference logo.

Link：https://doi.org/10.1093/pcp/pcz066

Plants have evolved two phylogenetically separated and elaborately regulated strategies to mobilize iron from the soil, featuring mechanisms which are thought to be mutually exclusive. Louis Grillet and Wolfgang Schmidt use publicly available data obtained from the model species rice (Oryza sativa) to unveil similarities and incongruities between co-expression networks derived from transcriptomic profiling of iron-deficient rice and Arabidopsis plants. This approach revealed striking similarities in the topographies of the resulting co-expression networks with relatively minor deviations in the molecular attributes of the comprised genes, which nonetheless lead to different physiological functions.

Link：

https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.16005

Nitrogen (N) starvation triggers an accumulation of oil in photosynthetic cells of plants and algae. A research team led by Dr. Nakamura discovered a pair of enzyme LPAT4 and LPAT5 required for oil production in N-starved Arabidopsis. This work reveals an important pathway for oil production and a mechanism in flux control of a balance between membrane and storage lipids.

In animal cells, homeostasis of ER phospholipid phosphatidylcholine is crucial in circumventing ER stress, an organelle stress that leads to serious diseases. A research team led by Dr. Nakamura demonstrated that plant ER stress tolerance requires balanced choline/phosphocholine ratio rather than phosphatidylcholine, which is maintained by a newly characterized choline kinase CEK1. The work highlights phosphocholine metabolism as a key metabolite in plant ER stress, which is caused by agriculturally important environmental stresses such as heat and salinity.

https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.15915

The 19^th edition of at the International Symposium on Iron Nutrition and Interactions in Plants (ISINIP) was hosted by IPMB from July 9 to 13, 2018 at the Academia Sinica campus. The five-day event hosted around 200 scientists from around the world. The meeting covered a diverse array of topics centered around iron nutrition, including but not limited to soil processes, biofortification, transport, signaling, and molecular processes regulating the cellular homeostasis of iron. A review of the meeting summarizing the main findings has recently been published in Plant Cell and Physiology (PCP), one of the main sponsors of the event (https://academic.oup.com/pcp/advance-article-abstract/doi/10.1093/pcp/pcz066/5488000?redirectedFrom=fulltext). A spotlight issue comprising four reviews summarizing the most prominent subjects of the symposium edited by Wolfgang Schmidt will be published  in PCP in due course.