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Project: Do leaf endophytes influence plant heat stress response?

Project title:

Do leaf endophytes influence plant heat stress response?


Mentor name: Martijn Slot
Co-mentor: Luis Mejía, Scientist at Indicasat
Contact information:
Mentor: slotm@si.edu
Co-Mentor: LMejia@indicasat.org.pa

Location of internship
Panama City and Gamboa

Will mentor be at this location?
Yes. The mentors have offices in Panama City, but ongoing projects in Gamboa


Project summary and objectives

As global temperatures are rising an important question is how tropical forests will respond to temperatures that they haven’t experienced for millions of years. Tropical forests are critically important for the global carbon cycle and changes in the capacity of tropical trees to fix atmospheric carbon in photosynthesis in response to climate change could have global consequences. At the same time, there is growing understanding of the role that plant-associated microbes can play in the way in which plants respond to environmental perturbations (e.g., Lata et al., 2018). The role of microbes in the plant temperature response of tropical tree species is, however, unknown.

In this project we will grow Theobroma cacao seedlings at two different temperatures, and measure temperature response curves of various parameters associated with the photosynthetic capacity, and we will determine the survival threshold temperature for leaves. Half of the seedlings will be free of endophytes, and the other half will be inoculated with naturally-occurring endophytes. Comparison of the temperature response curves of plants grown at ambient and elevated temperatures will allows us to determine whether these cacao seedlings can acclimate to predicted future temperatures. Comparison between inoculated and endophyte-free seedlings will allow us to determine whether endophytes play a role in plant temperature responses and in the acclimation of such temperature responses. In addition, we will study gene expression patterns using transcriptomics approaches, to establish whether plants with and without endophytes have different patterns in gene expression. Of particular interest will be the expression of heat shock proteins, which are known to play a role in protecting plants to transient heat exposure (Vierling 1991; Zhu et al., 2024).

Lata R, Chowdhury S, Gond SK, White Jr JF (2018) Induction of abiotic stress tolerance in plants by endophytic microbes. Lett. Appl. Microbiol. 66, 268-276.
Vierling E (1991) The roles of heat shock proteins in plants. Annu. Rev. Plant Biol. 42, 579-620.

Zhu L, Scafaro AP, Vierling E, Ball MC, Posch BC, Stock F, Atkin OK (2024) Heat tolerance of a tropical–subtropical rainforest tree species Polyscias elegans: time‐dependent dynamic responses of physiological thermostability and biochemistry. New Phytol. 241, 715-731.


Mentorship goals including benefits to the intern

This project will provide diverse learning opportunities to the intern, as it merges plant ecophysiology with microbiology, genomics and bioinformatics, and the intern will have the opportunity to be involved in all steps. Part of the project will take place at STRI, and the other part will take place at Indicasat, further broadening the exposure to different research settings and different groups of scientists for the intern. Attending seminars at STRI (Tupper/ Bambi) and Indicasat will provide the intern with opportunities to learn about a wide range of research topics and to interact with the wider fellow community.

At the end of the project the intern will be fully trained in using infrared gas analyzers to measure different photosynthesis parameters, will have mastered the protocol for determining leaf heat tolerance, and will have hands on experience with microbiology and transcriptomics techniques and data analysis. The intern will receive further training in experimental design, basis statistical analyses and report writing. Any scientific publication that may result from the study will be coauthored by the intern.

Intern’s role, desired background and expected products

The intern will be working alongside Drs Slot and Mejía. They will receive further support from Dr Slot’s lab technician for the physiological parameters, and Dr Mejía’s for the microbiology and gene expression components of the study. The appointment is full time over a 3-month period, with expected time allocation of 50% measurements of physiological parameters (Gamboa), 30% laboratory work (Indicasat) and 20% data analysis and writing. It is expected that by the end of the internship period, an informal report is produced and presented to the mentors on the results and outcomes (to be later developed into or incorporated into a scientific publication).

What are the regularly held occasions for group discussions, attendance at lectures, career counseling, and other educational and experiential opportunities?

The intern attends a weekly project group meeting for discussion and feedback with both mentors present and other members of the two lab groups, and will have daily supervision from the project team.

The intern will have the opportunity to attend Bambi and Tupper seminars at STRI and seminars/lab meetings at Indicasat.
The mentors will discuss the project and outcomes with the intern to ensure that they are receiving the training that is targeting specific needs for the intern to progress in their scientific career (e.g. experimental design, analytical skills), and to provide guidance on their next scientific career steps (e.g. PhD programs).

List of suggested publication or reading related to this project

• Slot M, Cala D, Aranda J, Virgo A, Michaletz ST, Winter K (2021) Leaf heat tolerance of 147 tropical forest species varies with elevation and leaf functional traits, but not with phylogeny. Plant, Cell & Environment 44, 2414−2427.

• Slot M, Winter K (2017) Photosynthetic acclimation to warming in tropical forest tree seedlings. Journal of Experimental Botany 68, 2275-2284.

• Mejía, L.C., Herre, E.A., Sparks, J.P., Winter, K., García, M.N., Van Bael, S.A., Stitt, J., Shi, Z., Zhang, Y., Guiltinan, M.J. and Maximova, S.N., 2014. Pervasive effects of a dominant foliar endophytic fungus on host genetic and phenotypic expression in a tropical tree. Frontiers in Microbiology 5, 479.

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