Tissue-specific systemic responses of the wild tobacco Nicotiana attenuata against stem-boring herbivore attack

Lee, Gisuk,Joo, Youngsung,Baldwin, Ian T.,Kim, Sang-Gyu The Ecological Society of Korea 2021 Journal of Ecology and Environment Vol.45 No.3

Background: Plants are able to optimize defense responses induced by various herbivores, which have different feeding strategies. Local and systemic responses within a plant after herbivory are essential to modulate herbivore-specific plant responses. For instance, leaf-chewing herbivores elicit jasmonic acid signaling, which result in the inductions of toxic chemicals in the attacked leaf (tissue-specific responses) and also in the other unattacked parts of the plant (systemic responses). Root herbivory induces toxic metabolites in the attacked root and alters the levels of transcripts and metabolites in the unattacked shoot. However, we have little knowledge of the local and systemic responses against stem-boring herbivores. In this study, we examined the systemic changes in metabolites in the wild tobacco Nicotiana attenuata, when the stem-boring herbivore Trichobaris mucorea attacks. Results: To investigate the systemic responses of T. mucorea attacks, we measured the levels of jasmonic acid (JA), JA-dependent secondary metabolites, soluble sugars, and free amino acids in 7 distinct tissues of N. attenuata: leaf lamina with epidermis (LLE), leaf midrib (LM), stem epidermis (SE), stem pith (SP), stem vascular bundle (SV), root cortex with epidermis (RCE), and root vascular bundle (RV). The levels of JA were increased in all root tissues and in LM by T. mucorea attacks. The levels of chlorogenic acids (CGAs) and nicotine were increased in all stem tissues by T. mucorea. However, CGA was systematically induced in LM, and nicotine was systematically induced in LM and RCE. We further tested the resource allocation by measuring soluble sugars and free amino acids in plant tissues. T. mucorea attacks increased the level of free amino acids in all tissues except in LLE. The levels of soluble sugars were significantly decreased in SE and SP, but increased in RV. Conclusions: The results reveal that plants have local- and systemic-specific responses in response to attack from a stem-boring herbivore. Interestingly, the level of induced secondary metabolites was not consistent with the systemic inductions of JA. Spatiotemporal resolution of plant defense responses against stem herbivory will be required to understand how a plant copes with attack from herbivores from different feeding guilds.

A robust genome-editing method for wild plant species Nicotiana attenuata

강문영,안효민,Eva Rothe,Ian T. Baldwin,Kim Sang-Gyu 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.5

CRISPR genome-editing techniques theoretically enable us to edit any genes in any plants. However, plant tissue culture is required for generating targeted mutants in plants, except in some model plant species such as Arabidopsis thaliana. To modify ecologically or agronomically important traits in plants using the CRISPR system, a robust plant regeneration method and efcient genome-editing tools must be developed. This study shows the entire process of genome editing and the regeneration process for wild tobacco, Nicotiana attenuata. We delivered T-DNA harboring Streptococcus pyogenes Cas9 (SpCas9) and guide RNA (gRNA) via Agrobacterium-mediated transformation into the hypocotyl cells of the wild tobacco and regenerated gene-edited plants. The efcacy of genome editing was measured in N. attenuata protoplasts in which SpCas9 and gRNA were transiently expressed. Light intensity (476.66–627.00 μW/cm2 , 20.69–52.21 μE) was optimized to enhance the emergence of plant shoots during callus induction, and the core step of dealing with plant tissues was recorded. In addition, we found that wounding the bottom part of mature plants was critical for root regeneration. By tracking mutation patterns and efciency at each regeneration step, we found that the mutation was induced early on in the tissue culture process and maintained throughout the regeneration process. Genome-editing techniques have opened the way to study the function of the genes in all plants, and this study will provide guidelines for editing a gene in the plant of interest.

Chemical ecology meets molecular biology: the plant defense system against Trichobaris weevil attacks

Sang-Gyu Kim,Gisuk Lee,Youngsung Joo,Ian T. Baldwin 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.04

Herbivorous insects use plant metabolites to inform their host plant selection for oviposition. These host-selection behaviors are often consistent with the preference-performance hypothesis; females oviposit on hosts that maximize the performance of their offspring. However, the metabolites used for these oviposition choices and those responsible for differences in offspring performance remain unknown for ecologically-relevant interactions. In this time, I will talk about the host-selection behaviors of two sympatric weevils, the Datura (Trichobaris compacta) and tobacco (T. mucorea) weevils in field- and glasshouse-experiments with transgenic host plants specifically altered indifferent components of their secondary metabolism. In addition, I will show that adult females are able to choose the best host plant for their offspring and use chemicals different from those that influence larval performance to inform their oviposition decisions.

Training Molecularly Enabled Field Biologists to Understand Organism-Level Gene Function

강진호,Ian T. Baldwin 한국분자세포생물학회 2008 Molecules and cells Vol.26 No.1

A gene’s influence on an organism’s Darwinian fitness ultimately determines whether it will be lost, maintained or modified by natural selection, yet biologists have few gene expression systems in which to measure whole-organism gene function. In the Department of Molecular Ecology at the Max Planck Institute for Chemical Ecology we are training “molecularly enabled field biologists” to use transformed plants silenced in the expression of environmentally regulated genes and the plant’s native habitats as “laboratories.” Research done in these natural laboratories will, we hope, increase our understanding of the function of genes at the level of the organism. Examples of the role of threonine deaminase and RNA-directed RNA polymerases illustrate the process.

Circadian clock component, lhy, tells a plant when to respond photosynthetically to light in nature

Joo, Youngsung,Fragoso, Variluska,Yon, Felipe,Baldwin, Ian T.,Kim, Sang‐,Gyu Wiley-Blackwell 2017 Journal of integrative plant biology Vol.59 No.8

Native root-associated bacteria rescue a plant from a sudden-wilt disease that emerged during continuous cropping

Santhanam, Rakesh,Luu, Van Thi,Weinhold, Arne,Goldberg, Jay,Oh, Youngjoo,Baldwin, Ian T. National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.36

<P><B>Significance</B></P><P>Plant roots associate with the diverse microbial community in soil and can establish mutualistic relationships with microbes. The genetic characterization of the plant microbiome (total microbiota of plants) has intensified, but we still lack experimental proof of the ecological function of the root microbiome. Without such an understanding, the use of microbial communities in sustainable agricultural practices will be poorly informed. Through continuous cropping of a seed-sterilized native plant, we inadvertently recapitulated a common agricultural dilemma: the accumulation of phytopathogens. Experimental inoculations of seeds with native bacterial consortium during germination significantly attenuated plant mortality, demonstrating that a plant’s opportunistic mutualistic associations with soil microbes have the potential to increase the resilience of crops.</P><P>Plants maintain microbial associations whose functions remain largely unknown. For the past 15 y, we have planted the annual postfire tobacco <I>Nicotiana attenuata</I> into an experimental field plot in the plant’s native habitat, and for the last 8 y the number of plants dying from a sudden wilt disease has increased, leading to crop failure. Inadvertently we had recapitulated the common agricultural dilemma of pathogen buildup associated with continuous cropping for this native plant. Plants suffered sudden tissue collapse and black roots, symptoms similar to a <I>Fusarium</I>–<I>Alternaria</I> disease complex, recently characterized in a nearby native population and developed into an in vitro pathosystem for <I>N</I>. <I>attenuata</I>. With this in vitro disease system, different protection strategies (fungicide and inoculations with native root-associated bacterial and fungal isolates), together with a biochar soil amendment, were tested further in the field. A field trial with more than 900 plants in two field plots revealed that inoculation with a mixture of native bacterial isolates significantly reduced disease incidence and mortality in the infected field plot without influencing growth, herbivore resistance, or 32 defense and signaling metabolites known to mediate resistance against native herbivores. Tests in a subsequent year revealed that a core consortium of five bacteria was essential for disease reduction. This consortium, but not individual members of the root-associated bacteria community which this plant normally recruits during germination from native seed banks, provides enduring resistance against fungal diseases, demonstrating that native plants develop opportunistic mutualisms with prokaryotes that solve context-dependent ecological problems.</P>

Targeted inactivation of transcription factors by overexpression of their truncated forms in plants

Seo, Pil Joon,Hong, Shin‐,Young,Ryu, Jae Yong,Jeong, Eun‐,Young,Kim, Sang‐,Gyu,Baldwin, Ian T.,Park, Chung‐,Mo Blackwell Publishing Ltd 2012 The Plant journal Vol.72 No.1

<P><B>Summary</B></P><P>Transcription factors are central constituents of gene regulatory networks that control diverse aspects of plant development and environmental adaptability. Therefore they have been explored for decades as primary targets for agricultural biotechnology. A gene of interest can readily be introduced into many crop plants, whereas targeted gene inactivation is practically difficult in many cases. Here, we developed an artificial small interfering peptide (a‐siPEP) approach, which is based on overexpression of specific protein domains, and evaluated its application for the targeted inactivation of transcription factors in the dicot model, Arabidopsis, and monocot model, <I>Brachypodium</I>. We designed potential a‐siPEPs of two representative MADS box transcription factors, SUPPRESSOR OF OVEREXPRESSOR OF CONSTANS 1 (SOC1) and AGAMOUS (AG), and a MYB transcription factor, LATE ELONGATED HYPOCOTYL (LHY). Transgenic plants overproducing the a‐siPEPs displayed phenotypes comparable to those of gene‐deficient mutants. The a‐siPEPs attenuate nuclear import and DNA‐binding of target transcription factors. Our data demonstrate that the a‐siPEP tool is an efficient genetic means of inactivating specific transcription factors in plants.</P>

Fitness consequences of altering floral circadian oscillations for<i>Nicotiana attenuata</i> : Fitness consequences of altering floral circadian rhythms

Yon, Felipe,Kessler, Danny,Joo, Youngsung,Corté,s Llorca, Lucas,Kim, Sang-Gyu,Baldwin, Ian T. Wiley (Blackwell Publishing) 2017 Journal of integrative plant biology Vol.59 No.3

<P>Ecological interactions between flowers and pollinators are all about timing. Flower opening/closing and scent emissions are largely synchronized with pollinator activity, and a circadian clock regulates these rhythms. However, whether the circadian clock increases a plant's reproductive success by regulating these floral rhythms remains untested. Flowers of Nicotiana attenuata, a wild tobacco, diurnally and rhythmically open, emit scent and move vertically through a 140 degrees arc to interact with nocturnal hawkmoths. We tethered flowers to evaluate the importance of flower positions for Manduca sexta-mediated pollinations; flower position dramatically influenced pollination. We examined the pollination success of phase-shifted flowers, silenced in circadian clock genes, NaZTL, NaLHY, and NaTOC1, by RNAi. Circadian rhythms in N. attenuata flowers are responsible for altered seed set from outcrossed pollen.</P>