Recognizing Plant Cell authors: Taylor AuBuchon-Elder

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Taylor AuBuchon-Elder, co-first author of Sterile spikelets contribute to yield in sorghum and related grasses

Current Position: Senior lab technician

Education: B.A. Biological Sciences Webster University, St. Louis, Missouri

Non-scientific interests: cooking, gardening, traveling, activism, and politics

Brief Bio: When I began my undergraduate education I originally planned on focusing on studio art, but I ended up starting a full biological sciences course load, and the rest is history. While I earned my biology degree, I was also fortunate enough to minor in environmental studies and sustainability, which broadened my interests and discipline, and has allowed me to apply a more interdisciplinary approach to my research.

I’m passionate about plant biodiversity, preserving natural resources, and encouraging good stewardship of our environment. My work in the Kellogg Lab at the Donald Danforth Plant Science Center lets me study the genetic basis of wild grass diversity and how it applies to improving sustainability of cereal agriculture. Sometimes people ask me why I would bother working with grass; but I often remind them that grasses like corn, rice, and wheat have been supporting human civilizations for millennia!

Today I am leading the germplasm acquisition and maintenance of over 1,000 species of wild grass from all around the world because of their special abilities in heat and drought tolerance and their evolutionary relationships to staple crops. This work involves extensive planning, travel, navigating geospatial data, resolving taxonomic issues, and managing hundreds of very robust plants from the wild! We aim to understand the mechanisms responsible for their adaptations to abiotic stress, and provide that information to improve crop efficiency in a changing climate.

I’m currently weighing my options and goals for graduate school in this uncertain time; but I look forward to continuing research on wild plants and the answers they can provide to us for working towards a more sustainable future.

Towards Uncovering the Developmental Mechanisms of Elaborate Petals: Nigella damascena as a Beginning

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Zhang et al. explore the mechanisms underlying elaborate petal development and specialized character formation in Nigella damascena. Plant Cell https://doi.org/10.1105/tpc.20.00330

By Rui Zhang, Xuehao Fu, Caiyao Zhao, Jie Cheng, Hongyan Shan, and Hongzhi Kong

Background: Petals can be simple or elaborate, depending on whether they have modifications along their margins or on their adaxial/abaxial side, or both. Elaborate petals have been recorded in many flowering plants and are believed to have played key roles in the adaptive evolution of the corresponding lineages. Many elaborate petals also bear highly specialized morphological features, suggestive of lineage-specific new character originations. The mechanisms underlying the formation of elaborate petals, however, are largely unclear.

Question: Petals of Nigella damascena (Ranunculaceae) have long been recognized as being elaborate, possessing not only a stalked bilabiate basic structure but also several highly specialized morphological characters (e.g., long hairs, short trichomes, nectary, and pseudonectaries). So, which genes or programs are required for the formation of elaborate petals in N. damascena and, of them, which are shared by, or different between, elaborate and simple petals?

Findings: By performing detailed time-course transcriptomic analyses, we not only found the genes and programs that are specifically or preferentially expressed in N. damascena petals but also discerned those that are required for elaborate rather than simple petal development. By correlating the expression patterns of genes and developmental changes of petals, we also identified 30 candidate genes that may play key roles in elaborate petal development (including the establishment of the bilabiate basic structure and the initiation of the aforementioned highly specialized morphological characters). Functional analyses further suggested that one of the candidate genes, NidaLMI1, whose counterparts in other species are involved in the formation of dissected leaves, tendrils or trichomes rather than petal development, appears to be indispensable for the initiation of short trichomes and the bifurcation of the lower petal lips.

Next steps: We plan to conduct detailed expression and functional investigations on other candidate genes, identify the other genes and programs required for elaborate petal development and elucidate the mechanisms underlying elaborate petal evolution.

Rui Zhang, Xuehao Fu, Caiyao Zhao, Jie Cheng, Hong Liao, Peipei Wang, Xu Yao, Xiaoshan Duan, Yi Yuan, Guixia Xu, Elena M Kramer, Hongyan Shan, and Hongzhi Kong. (2020). Identification of the Key Regulatory Genes Involved in Elaborate Petal Development and Specialized Character Formation in Nigella damascena (Ranunculaceae). Plant Cell. https://doi.org/10.1105/tpc.20.00330.

Recognizing Plant Physiology authors: Mark Jenness

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Mark Jenness, first author of An ATP-binding cassette transporter, ABCB19, regulates leaf position and morphology during phototropin1-mediated blue light responses

Current Position: Postdoctoral scholar at the University of Maryland

Education: Ph.D. in Plant Sciences from the University of Maryland, College Park; B.S. in Biology from California State University, Monterey Bay

Non-scientific Interests: golf, skiing, fermentation (bread and beer!)

Brief bio: I have always had a love for STEM, and during my undergraduate studies courses in biochemistry and molecular cell biology piqued my curiosity. The influence of growing up in the California Bay Area had my initial interests in biotechnology and pharmaceuticals, however, an NSF summer internship in plant biology shifted my career toward plant research. For my Ph.D. I joined Angus Murphy’s lab to work on a project that integrated all these interests: plant ABCB transporters. In plants, ABCBs mobilize a small subset of amphipathic and aromatic organic acids but in mammals transport a broad range of drugs and chemotherapeutics. During my Ph.D. I worked on characterizing several ABCB transporters and how they participate in the movement of the phytohormone auxin during growth and development. As I continue as a postdoctoral scholar in the Murphy lab, I am working to understand how these proteins function at the molecular level and how they compare to their mammalian relatives. Further, I am interested in understanding the mechanisms of substrate recognition and the role local lipid environments play in ABCB transporter functionality.

Recognizing Plant Cell authors: Yue Liang

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Yue Liang, first author of Auxin regulates sucrose transport to repress petal abscission in rose (Rosa hybrida)

Current Position: PhD, College of Horticulture, China Agricultural University, Beijing, China

Education: PhD, MS and BS from China Agricultural University, Beijing, China

Non-scientific Interests: jogging, basketball, hiking

Brief bio: After completing my BS and MS studies, I joined the department of ornamental horticulture at China Agricultural University to pursue my PhD degree under the supervision of prof. Bo Hong, Junping Gao, and Chao Ma. My PhD thesis is about the regulatory mechanism of rose petal abscission. It has been well-known that auxin and sucrose can inhibit organ abscission in plants. However, the interaction of auxin and sucrose involved in organ abscission remains unknown. In our study, we found that auxin modulates sucrose transport during petal abscission, and that this process is regulated by a RhARF7-RhSUC2 module in the petal abscission zone. This study makes me fascinated about the regulatory mechanism of flower development process. In the future, I hope I can get more interesting discoveries from my studies.

 

姓名：梁跃

现在职位：中国农业大学博士

教育经历：中国农业大学农学博士、硕士和学士

兴趣爱好：跑步、蓝球、徒步

个人简介：在完成学士和硕士学习后，我有幸加入洪波、高俊平和马超教授课题组攻读博士学位，开展关于月季花瓣脱落分子调控机制方面的研究。生长素和蔗糖对植物器官脱落均起抑制作用，但二者的相互作用关系尚不明确。我们的研究发现在花瓣脱落过程中，生长素调控了蔗糖向月季花瓣的运输，进而调节花瓣脱落进程，并且这一过程是通过生长素响应因子RhARF7调控蔗糖运输蛋白RhSUC2基因的表达来实现。通过这项研究，我对植物花器官发育调控机制产生了浓厚的兴趣，希望在以后的研究工作中获得更多有趣的发现。

Recognizing Plant Physiology authors: Lena Maria Müller

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Lena Maria Müller, first author of Constitutive overexpression of RAM1 leads to an increase in arbuscule density in Brachypodium distachyon

Current Position: Postdoctoral researcher at Boyce Thompson Institute/Cornell University, Ithaca, NY (USA)

Education: PhD in Plant Science and Policy: University of Zurich, Switzerland; B.S./M.Sc. in Biology: University of Tuebingen, Germany

Non-scientific Interests: I enjoy the outdoors, travelling, and being creative (pottery, painting, photography).

Brief bio: I first got in touch with plant biology as an undergraduate researcher studying vesicle trafficking during polar tip growth with Dr. Gerd Jürgens at the University of Tübingen (Germany). My growing interest in plant signaling led me to pursue my PhD work with Dr. Ueli Grossniklaus at the University of Zurich (Switzerland), where I investigated species-specific communication mechanisms between male and female gametophytes in the genus Arabidopsis. This work spiked my interest in cell-cell communication, and I moved to conduct a postdoc with Dr. Maria Harrison at the Boyce Thompson Institute (BTI) at Cornell University (USA). Here I began to study plant signaling networks in the context of plant-fungal interactions during arbuscular mycorrhizal symbiosis – a mutually beneficial interaction between plants and soil fungi centered on nutrient exchange. I am particularly fascinated by the molecular mechanisms of how plants reprogram their root cells to accommodate the fungal symbiont, and how local and systemic signaling within the plant fine-tunes fungal colonization. This Plant Physiology paper was a true team effort, and I am very grateful to all my co-authors.

Recognizing Plant Cell authors: Zhaoxia Li

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Zhaoxia Li, first author of The transcription factor bZIP60 links the Unfolded Protein Response (UPR) to the Heat Stress Response (HSR) in maize

Current Position: Postdoctoral researcher, Plant Sciences Institute, Iowa State University, Ames, IA, USA

Education: BSc in Bioscience from Tangshan Normal College, PhD in Cell biology from Shandong University, China

Non-scientific Interests: traveling, cooking, raising cats

Brief Bio: I started my journey of scientific learning in 2003 when I joined the lab of Dr. Chao Chen at Tangshan Normal College, and where I finished my BSc in Bioscience. I was fascinated by the utility and power of plant sciences in agriculture and how they improved our life quality. Therefore, I joined the lab of Dr. Juren Zhang for my Ph.D. and studied how maize plants adapt to abiotic stresses.  I was especially interested in how some of the drought and low-phosphate stress genes could be genetically engineered to improve plant resistant to abiotic stress.  I moved to Dr. Stephen Howell’s lab in 2016 to pursue postdoctoral research. Here, I have been studying Endoplasmic Reticulum (ER) stress in maize, and its relationship to other abiotic stresses, such as heat stress. ER stress is activated by misfolded proteins that accumulate in the ER under adverse environmental conditions. ER stress responses mitigate the damage caused by stress and confer levels of stress tolerance to plants. In my work, I have uncovered the contribution of ER stress to heat stress responses in maize.

Recognizing Plant Physiology authors: Premachandran Yadukrishnan

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Premachandran Yadukrishnan, first author of HY5 suppresses, rather than promotes, ABA-mediated inhibition of post-germination seedling development

Current Position: Research Associate (ad hoc), Indian Institute of Science Education and Research (IISER) Bhopal, India

Education: Ph.D. (Biological Sciences) from IISER Bhopal, India; M.Sc. Agri. (Molecular Biology & Biotechnology) from G.B. Pant University of Agriculture & Technology, Pantnagar, India; B.Sc. Agriculture from Tamil Nadu Agricultural University, India

Non-scientific interests: reading, music, football

Brief bio: I completed my bachelors in Agriculture from Tamil Nadu Agricultural University in 2012. After finishing M.Sc. Agri with a major in Molecular Biology & Biotechnology from G.B. Pant University Pantnagar, I joined Dr. Sourav Datta’s lab at IISER Bhopal for my doctoral research in 2014. I was mainly interested in exploring the interactions between light and abscisic acid signaling pathways during early plant development, and identified that COP1, a central negative regulator of light signaling, enhances ABA responsiveness of seedlings during their post-germination growth in darkness. We found that COP1 promotes ABA signaling by acting downstream of the key ABA signaling gene ABI5 and facilitate the binding of ABI5 on its target promoters through unknown mechanisms (this work was published in The Plant Journal earlier this year). After completing my Ph.D., I decided to continue in Dr. Datta’s lab for a short period to further investigate the molecular basis of the ABA hyposensitive post-germination phenotype of cop1 mutants. I examined its dependence on HY5, an important light signaling factor and a degradation substrate of COP1, in this process. Although previous reports indicated that HY5 acts as a positive regulator of ABA signaling, we found that HY5 suppresses, rather than promotes, ABA-mediated arrest of post-germination growth. Through this finding published as a letter in Plant Physiology, we propose a revised role of HY5 in integrating ABA and light signaling during early seedling development. In future, I look forward to exploring more about environmental control of phytohormone networks during early plant development.

Recognizing Plant Physiology authors: Robert Orr

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Robert Orr, first author of Robust survival-based RNAi of gene families using in tandem silencing of adenine phosphoribosyltransferase

Current Position: Ph.D. Candidate and Research Assistant in Luis Vidali’s laboratory at Worcester Polytechnic Institute

Education: Ph.D. Candidate in Biology and Biotechnology at Worcester Polytechnic Institute, Worcester, MA, USA; B.A. in Molecular, Cellular, and Developmental Biology at University of Colorado, Boulder, CO, USA

Non-scientific Interests: reading, exercise, games, travel, cinema

Brief bio: I was introduced to the world of scientific research during my freshman year when I volunteered in the laboratory of Dr. Glenn Gaudette, a faculty member of the Biomedical Engineering department at Worcester Polytechnic Institute. I was hooked, and I returned as a summer intern every year! Following graduation, I worked as his lab manager and research technician where we investigated the use of induced pluripotent stem cells to functionally replace the damaged myocardium following a heart attack. This experience was invaluable, but I knew I wanted to pursue basic research in cell biology. I joined the lab of Dr. Luis Vidali for my Ph.D., as I loved the rigorous and quantitative approach Luis applies to address fundamental questions in plant cell biology. During my time in the Vidali lab, I have investigated the mechanism of polarized trafficking in tip growing cells, as well as developed a positive selection-based RNAi technology that I hope will benefit the community as much as it has benefited our lab.

It takes two to be you: promoter motif pairs keep immune responses within cell identity boundaries

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Being a multicellular organism is not an easy task. Proper functioning of individual cell types with different functions requires coordination of gene expression to determine cell identity, but also regulatory mechanisms to respond to environmental cues. The root may appear simple at first sight, but it is built with 15 cell types, each having an individual transcriptional profile, facilitating their functional specialization (Brady et al., 2007).

Root developmental processes are tightly interconnected with responses to the environment (Iyer-Pascuzzi et al., 2011). Several abiotic stresses have been shown to elicit cell type-specific responses. At the same time, root cell identity is maintained during stress and several cell identity regulators play an important role in stress responses (Iyer-Pascuzzi et al., 2011). Similarly, biotic stress responses show cell type‑specificity (Walker et al., 2017), yet it remains unknown how the root immunity and cell identity regulatory networks connect.

To tackle this question, Rich-Griffin et al. (2020) investigated cell type-specific regulatory patterns activated by biotic stress. The authors treated Arabidopsis roots with elicitors of Pattern Triggered Immunity (PTI) signaling pathways leading to resistance to pathogens (Bigeard et al., 2015). With fluorescent-activated cell sorting, the authors profiled the transcriptomes of three root cell types—the two outermost root layers, epidermis and cortex, and the cell layer surrounding the root vasculature, the pericycle. More than half of the transcripts affected by PTI were expressed specifically in one out of three cell types. Moreover, expression of only a small proportion of the cell identity genes was changed by the immunity response. Together, these data suggest that despite strong cell type specificity in its response, PTI does not affect cell identity networks.

Next, Rich-Griffin et al. (2020) set out to identify which transcription factors connect cell identity and cell type-specific immunity networks. Given that control of gene expression often involves specific combinations of TF binding motifs (Lewis et al., 2015), the authors developed software called the Paired Motif Enrichment Tool (PMET) to identify such combinations. Using PMET, they identified two-motif combinations enriched in the promoters of cell identity genes and cell type-specific immunity genes. TFs acting in pairs with TFs from cell identity networks as well as cell type-specific immunity networks were assigned as core TFs, intersecting development and stress responses. In the epidermis, WRKY TFs (WRKY12/18/28/45) functioned as core TFs, acting in combination with ATHB (ARABIDOPSIS THALIANA HOMEOBOX), MYC and PIF (PHYTOCHROME INTERACTING FACTOR) TFs to regulate growth and development, while WRKYs combined with KAN (KANADI) and YAB (YABBY) TF networks to control epidermal immunity responses. In cortical cells, core TFs included MYC and ATHB TFs, whose binding sites were found in combination with cortex identity MYB binding elements, or with WRKY motifs in promoter regions of cortex-specific immunity genes.

The authors functionally validated a subset of identified motif pairs using a trans-activation YFP system. For example, native promoters with a WRKY-KAN motif co-activated YFP expression specifically in the epidermis, while replacing one of these motifs not only abolished basal YFP expression, but also prevented its induction by the PTI elicitor. Finally, the group designed a synthetic promoter containing the WRKY-KAN motif pair, which was sufficient to drive elicitor-induced YFP expression specifically in the epidermis. Narrowing down cell type-specific PTI to essential promoter elements and subsequent engineering of localized immune responses opens up exciting avenues for synthetic biology solutions to biotic stresses.

Together, Rich-Griffin et al. (2020) showed that immunity gene networks differ between root cell types and are interconnected with cell identity networks. Core TFs, acting as a “meeting point” for cell type‑specific immunity and cell identity networks, ensure that responses to pathogens are activated within the functional potential of individual root cell types. Sets of cell identity genes, whose cell type-specific expression is maintained under biotic (Rich-Griffin et al., 2020) or abiotic stresses (Iyer-Pascuzzi et al., 2011) preserve root cell identity under unfavorable conditions. It seems to be impossible to stress roots enough to cause their cells to lose their identity.

 

Dorota Kawa

Department of Plant Biology and Genome Center

University of California, Davis

[email protected]

ORCID: 0000-0002-4227-1621

 

REFERENCES

 

Bigeard J, Colcombet J, Hirt H (2015) Signaling mechanisms in pattern-triggered immunity (PTI). Mol Plant 8: 521-539

Brady SM, Orlando DA, Lee JY, Wang JY, Koch J, Dinneny JR, Mace D, Ohler U, Benfey PN (2007) A high-resolution root spatiotemporal map reveals dominant expression patterns. Science 318: 801-806

Iyer-Pascuzzi AS, Jackson T, Cui H, Petricka JJ, Busch W, Tsukagoshi H, Benfey PN (2011) Cell identity regulators link development and stress responses in the Arabidopsis root. Dev Cell 21: 770-782

Lewis LA, Polanski K, de Torres-Zabala M, Jayaraman S, Bowden L, Moore J, Penfold CA, Jenkins DJ, Hill C, Baxter L, Kulasekaran S, Truman W, Littlejohn G, Prusinska J, Mead A, Steinbrenner J, Hickman R, Rand D, Wild DL, Ott S, Buchanan-Wollaston V, Smirnoff N, Beynon J, Denby K, Grant M (2015) Transcriptional Dynamics Driving MAMP-Triggered Immunity and Pathogen Effector-Mediated Immunosuppression in Arabidopsis Leaves Following Infection with Pseudomonas syringae pv tomato DC3000. The Plant Cell 27: 3038-3064

Rich-Griffin C, Eichmann R, Reitz MU, Hermann S , Woolley-Allen K, Brown PE, Wiwatdirekkul K, Esteban E, Pasha A, Kogel K-H , Provart  AJ, Ott S, Schäfer P (2020) Regulation of Cell Type-Specific Immunity Networks in Arabidopsis Roots. The Plant Cell https://doi.org/10.1105/tpc.20.00154

Walker L, Boddington C, Jenkins D, Wang Y, Gronlund JT, Hulsmans J, Kumar S, Patel D, Moore JD, Carter A, Samavedam S, Bonomo G, Hersh DS, Coruzzi GM, Burroughs NJ, Gifford ML (2017) Changes in Gene Expression in Space and Time Orchestrate Environmentally Mediated Shaping of Root Architecture. Plant Cell 29: 2393-2412