Faculty

Siela Maximova

Research Professor of Plant Biotechnology Co-Director, Endowed Program in the Molecular Biology of Cocoa
Plant Institute, Director for Partnership

421 Huck Life Sciences
University Park, PA

Email snm104@psu.edu
Phone 814-863-7286

Overview

Molecular basis of plant-pathogen and plant-endophyte interactions. Biotechnology of tree crops. Development of sustainable energy crops.

Areas of Expertise

Theobroma Cacao Keyphrases
Cacao Keyphrases
Cacao Biochemistry, Genetics and Molecular Biology
Theobroma Cacao Agricultural and Biological Sciences
Somatic Embryogenesis Agricultural and Biological Sciences
Somatic Embryogenesis Keyphrases
Infectious Agent Biochemistry, Genetics and Molecular Biology
Arabidopsis Keyphrases

Correction to
Evelyn Kulesza, Helene Hopfer, Gregory Ray Ziegler, Juan Calle‑Bellido, Chelsea Roberts, Pathmanathan Umaharan, Siela Maximova, Mark Guiltinan, Dec 2025, In: Tropical Plant Biology
Date: Dec 2025

The Effect of Maternal and Paternal Genotype on seed Lipid Content, Composition, and Thermal Traits in in Clone Cacao Crossings Sca6 x Pa150, in St. Augustine
Evelyn Kulesza, Helene Hopfer, Gregory R. Ziegler, Juan Calle-Bellido, Chelsea Roberts, Pathmanathan Umaharan, Siela N. Maximova, Mark J. Guiltinan, Dec 2025, In: Tropical Plant Biology
Date: Dec 2025

Developing a core collection for the conservation of Theobroma cacao’s genetic diversity
Evelyn T. Todd, Fabrizio Arigoni, James A. Holzwarth, Laurence Bellanger, Patrick Descombes, Eduardo Beche, Tony Lass, Mark J. Guiltinan, Siela N. Maximova, Mariela Leandro, Virginie Mérot, Maud Lepelley, Audrey Fillodeau, Dec 2025, In: BMC genomics
Date: Dec 2025

Local gene duplications drive extensive NLR copy number variation across multiple genotypes of Theobroma cacao
Noah P. Winters, Eric K. Wafula, Prakash R. Timilsena, Paula E. Ralph, Siela N. Maximova, Claude W. De Pamphilis, Mark J. Guiltinan, James H. Marden, Sep 2025, In: G3: Genes, Genomes, Genetics
Date: Sep 2025

Reduced Susceptibility to Phytophthora in Non-Transgenic Cacao Progeny Through CRISPR–Cas9 Mediated TcNPR3 Mutagenesis
Mark J. Guiltinan, Lena Landherr, Siela N. Maximova, Dante DelVecchio, Aswathy Sebastian, Istvan Albert, 2025, In: Plant Biotechnology Journal
Date: 2025

The cacao gene atlas
Evelyn Kulesza, Patrick Thomas, Sarah F. Prewitt, Akiva Shalit-Kaneh, Eric Wafula, Benjamin Knollenberg, Noah Winters, Eddi Esteban, Asher Pasha, Nicholas Provart, Craig Praul, Lena Landherr, Claude dePamphilis, Siela N. Maximova, Mark J. Guiltinan, Dec 2024, In: BMC plant biology
Date: Dec 2024

A combination of conserved and diverged responses underlies Theobroma cacao’s defense response to Phytophthora palmivora
Noah P. Winters, Eric K. Wafula, Benjamin J. Knollenberg, Tuomas Hämälä, Prakash R. Timilsena, Melanie Perryman, Dapeng Zhang, Lena L. Sheaffer, Craig A. Praul, Paula E. Ralph, Sarah Prewitt, Mariela E. Leandro-Muñoz, Diego A. Delgadillo-Duran, Naomi S. Altman, Peter Tiffin, Siela N. Maximova, C..., Dec 2024, In: BMC Biology
Date: Dec 2024

Accumulation of cadmium in soils, litter and leaves in cacao farms in the North Sierra Nevada de Santa Marta, Colombia
Daniel Guarín, Javier M. Martín-López, Zamir Libohova, Jhony Benavides-Bolaños, Siela N. Maximova, Mark J. Guiltinan, John Spargo, Mayesse da Silva, Alejandro Fernandez, Patrick Drohan, Mar 2024, In: Geoderma Regional
Date: Mar 2024

Cadmium contamination in cacao farms of Piura, North Peru
Daniel Guarín, Nadia Rodríguez Hamamura, Jesús Blancas Cortez, Jhony Benavides, John Spargo, Mark Guiltinan, Siela Maximova, Otilia Acha de la Cruz, Patrick J. Drohan, Dec 2023, In: Environmental Challenges
Date: Dec 2023

Evaluation of cacao projects in Colombia
Alejandro Gil, Mark Brennan, Anil Kumar Chaudhary, Siela N. Maximova, Apr 2023, In: Evaluation and Program Planning
Date: Apr 2023

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The genome of Theobroma cacao
Xavier Argout, Jerome Salse, Jean Marc Aury, Mark J. Guiltinan, Gaetan Droc, Jerome Gouzy, Mathilde Allegre, Cristian Chaparro, Thierry Legavre, Siela N. Maximova, Michael Abrouk, Florent Murat, Olivier Fouet, Julie Poulain, Manuel Ruiz, Yolande Roguet, Maguy Rodier-Goud, Jose Fernandes Barbosa-Neto..., Feb 2011, In: Nature Genetics
Citations: 629

Transient expression of CRISPR/Cas9 machinery targeting TcNPR3 enhances defense response in theobroma cacao
Andrew S. Fister, Lena Landherr, Siela N. Maximova, Mark J. Guiltinan, Mar 2 2018, In: Frontiers in Plant Science
Citations: 278

Pervasive effects of a dominant foliar endophytic fungus on host genetic and phenotypic expression in a tropical tree
Luis C. Mejía, Edward A. Herre, Jed P. Sparks, Klaus Winter, Milton N. García, Sunshine A. Van Bael, Joseph Stitt, Zi Shi, Yufan Zhang, Mark J. Guiltinan, Siela N. Maximova, 2014, In: Frontiers in Microbiology
Citations: 169

Enhanced somatic embryogenesis in Theobroma cacao using the homologous BABY BOOM transcription factor
Sergio L. Florez, Rachel L. Erwin, Siela N. Maximova, Mark J. Guiltinan, Wayne R. Curtis, May 16 2015, In: BMC plant biology
Citations: 148

Proanthocyanidin synthesis in Theobroma cacao
Yi Liu, Zi Shi, Siela Maximova, Mark J. Payne, Mark J. Guiltinan, Dec 5 2013, In: BMC plant biology
Citations: 143

Towards the understanding of the cocoa transcriptome
Xavier Argout, Olivier Fouet, Patrick Wincker, Karina Gramacho, Thierry Legavre, Xavier Sabau, Ange Marie Risterucci, Corinne Da Silva, Julio Cascardo, Mathilde Allegre, David Kuhn, Joseph Verica, Brigitte Courtois, Gaston Loor, Regis Babin, Olivier Sounigo, Michel Ducamp, Mark J. Guiltinan, Manuel ..., Oct 30 2008, In: BMC genomics
Citations: 128

Bacterial endophytes
Rachel L. Melnick, Nina K. Zidack, Bryan A. Bailey, Siela N. Maximova, Mark Guiltinan, Paul A. Backman, Jul 2008, In: Biological Control
Citations: 119

Somatic embryogenesis and plant regeneration from floral explants of cacao (Theobroma cacao L.) using thidiazuron
Z. Li, A. Traore, S. Maximova, M. J. Guiltinan, 1998, In: In Vitro Cellular and Developmental Biology - Plant
Citations: 109

Efficiency, genotypic variability, and cellular origin of primary and secondary somatic embryogenesis of Theobroma Cacao L.
Siela N. Maximova, Larence Alemanno, Ann Young, Nicole Ferriere, Abdoulaye Traore, Mark J. Guiltinan, 2002, In: In Vitro Cellular and Developmental Biology - Plant
Citations: 106

Investigation of Agrobacterium-mediated transformation of apple using green fluorescent protein
Siela N. Maximova, Abhaya M. Dandekar, Mark J. Guiltinan, Jun 1998, In: Plant molecular biology
Citations: 104

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Centers & Institutes

Plant Biology IGDP

Evelyn Kulesza

Elsevier Pure Profile

Participants at the “The Art of Chocolate: A Guided Tasting Experience,” held on Feb. 14, were guided through how professionals evaluate chocolate — including snap, sheen, aroma, the initial taste, and how it develops and resolves. Credit: Sara Usnick / Penn State. Creative Commons

February 25, 2026

The 'Spirit of Chocolate' celebrates chocolate as both science and story

Director Bruce Logan, fourth from left, stands with the IEE Research Award winners. From left to right are: Hong Wu, Lisa Emili, Nathaniel Warner, Brian Fronk and Margaret Busse. Lauren McPhillips is not pictured. Credit: Brenna Buck. All Rights Reserved.

January 27, 2025

Researchers recognized for excellence by Institute of Energy and the Environment

Mónica Medina, third from right, and Julian Prieto, first on left, participate in a COP16 panel discussion on coral reef conservation after a screening of the movie "Saving Atlantis" at the Museum of Art La Tertulia. Credit: Mónica Medina. All Rights Reserved.

December 02, 2024

Q&A: Penn State COP16 delegation contributes to biodiversity efforts

To recognize Penn State for its impactful cacao and chocolate research, the government of Ecuador gifted a replica of an ancient ceramic vessel containing remnants of cacao dating back 5,300 years. Present at the ceremony were, from left, Monica Sanchez, minister of the foreign service, Ecuador; Soledad Peña, office of deputy chief of mission, Embassy of Ecuador; Cristian Espinosa, ambassador of Ecuador in the United States; Mark Gultinan, professor of plant molecular biology and director of the Penn State Plant Institute; Siela Maximova, research professor of biotechnology and director for Latin America and the Caribbean, Penn State Global; Mariuxi Cárdenas Rodas, cultural and educational attaché; and Deanna Behring, assistant dean and director, Ag Sciences Global. Credit: Daryl Branford. All Rights Reserved.

November 22, 2024

Penn State receives replica of historic ceramic vessel from Ecuador government

Nine faculty members were named the 2024 IEE Fellows. In the front row, from left, are Heather Preisendanz, Nilanjan Ray Chaudhuri, Li Li and Miriam Freedman. In the back row, from left, are Adri van Duin, Charles Anderson, Armen Kemanian, Siela Maximova, Enrique Gomez (Not pictured: Karen Fisher-Vanden) Credit: Kevin Sliman. All Rights Reserved.

September 12, 2024

Nine researchers named Institute of Energy and the Environment Fellows

The Cacao Gene Atlas is a genomics resource freely available to the public. Researchers can use the atlas to simulate how knocking out or enhancing a gene may influence the chocolate tree, allowing them to test hypotheses without the expense or time of growing the plant. Credit: Mark Guiltinan/Penn State. All Rights Reserved.

June 26, 2024

Researchers compile Cacao Gene Atlas to help plant breeders boost chocolate tree

Institute of Energy and the Environment (IEE) Director Bruce Logan, center, with four of the six IEE Research Award winners, from left: Adri van Duin, Donghai Wang, Estelle Couradeau and Laura Leites. Siela Maximova and Allyson Muth were unable to attend the event. Credit: Brenna Buck. All Rights Reserved.

January 29, 2024

Six researchers recognized with Institute of Energy and the Environment Awards

Three projects have been awarded seed grants as part of the Penn State-Belize Foundation for Research and Environmental Education initiative. Faculty and students from Penn State will research agricultural and ecological sustainability, preservation of tropical rainforest ecosystems, and sustainable development in Belize. Credit: Contributed photo. All Rights Reserved.

October 16, 2023

Grants awarded to Penn State faculty for tropical ecosystems research in Belize

Graduate student Sarah Glass, advised by lead researcher Estelle Couradeau, assistant professor of soils and environmental microbiology, at the Chingaza Paramos field site in Colombia. The National Science Foundation award will support Glass' doctoral degree dissertation work. Credit: Penn State. Creative Commons

September 14, 2023

Penn State-led team to study climate-threatened Colombian Paramos’ soil microbes

The researchers have created a streamlined sample-collection protocol that only requires a single leaf disc. The leaf discs are preserved in a solvent that prevents degradation of clovamide, allowing large-scale sampling in greenhouses and fields without the need for refrigeration. IMAGE: BEN KNOLLENBERG/PENN STATE

December 23, 2020