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Research Project: Development of Pathogen- and Plant-Based Genetic Tools and Disease Mitigation Methods for Tropical Perennial Crops

Location: Sustainable Perennial Crops Laboratory

Title: Spatial patterning of chloroplasts and stomata in developing cacao leaves

Author
item Baek, Insuck
item LIM, SEUNGHYUN - Orise Fellow
item WEERARATHNE, VISNA - Orise Fellow
item LEEDONGHO - Orise Fellow
item BOTKIN, JACOB - University Of Minnesota
item Kirubakaran, Silvas
item Park, Sunchung
item Kim, Moon
item Meinhardt, Lyndel
item Ahn, Ezekiel

Submitted to: Communications Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2025
Publication Date: 4/4/2025
Citation: Baek, I., Lim, S., Weerarathne, V., Leedongho, Botkin, J., Kirubakaran, S.J., Park, S., Kim, M.S., Meinhardt, L.W., Ahn, E.J. 2025. Spatial patterning of chloroplasts and stomata in developing cacao leaves. Communications Biology. 8:554. https://doi.org/10.1038/s42003-025-08019-6.
DOI: https://doi.org/10.1038/s42003-025-08019-6

Interpretive Summary: Cacao (Theobroma cacao L.), a versatile tree species vital to the global chocolate industry, also supports the livelihoods of millions of smallholder farmers in the tropics. Understanding the rapid growth of new leaves in the tree is crucial for its development. We studied microscopic traits like chloroplast density, stomatal morphology, and distribution patterns to understand this growth process better. Our research, which used robust statistical analysis and machine learning model, revealed interesting patterns in cacao leaf growth dynamics. These findings are valuable for cacao farmers and have broader implications for understanding plant growth and development in different species.

Technical Abstract: Understanding chloroplast density (CD) and stomatal morphology (SMP) and the distribution patterns of chloroplasts (DPC) and stomata (DPS) play a pivotal role in studies on flush growth of tropical species. This study investigated CD, SMP, DPC, and DPS in Stage C; the rapid leaf chlorophyll accumulation phase of Theobroma cacao L. (cacao). Microscopic images characterized noticeable variations in DPC and DPS across interveinal leaf segments. The highest CD, SMP, DPC, and DPS were observed close to the Stage C leaf base and showed an acropetal increment along with leaf greenness, suggesting a correspondence between the developmental sequence of chloroplasts and stomata and cacao leaf ontogeny. Using a machine learning approach, this study also showed how chloroplast clusters and stomata morphology can be used to interpret data accurately, demonstrating their precision in understanding cacao leaf developmental biology. These results lay a strong foundation for future research on the development of chloroplasts and stomata in growing leaves.