P-320 - FLOWER MICROBES OF THE ENDEMIC SPECIES THESPESIA GRANDIFLORA AND THEIR GROWTH-PROMOTING TRAITS

Tuesday, August 5, 2025

10:15 AM - 11:00 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

KR

Katheryne J. Roque Cruz

Inter American University of Puerto Rico- Metro Campus
San Juan, Puerto Rico, United States

Author(s)

AC

Adriana Cruz

Inter American University of Puerto Rico- Metro Campus
San Juan, Puerto Rico, United States
AL

Adriana Lizasoain

Inter American University of Puerto Rico- Metro Campus
San Juan, Puerto Rico, United States
BR

Bryan Rosado

Inter American University of Puerto Rico- Metro Campus
San Juan, Puerto Rico, United States
II

Ivelisse Irizarry

Assistant Professor
Inter American University of Puerto Rico- Metro Campus
San Juan, Puerto Rico, United States

Abstract Text: Flowers are ephemeral plant organs involved in plant reproduction that are colonized by microbes. Puerto Rico’s national flower is commonly known as the Maga flower, and it is produced by the endemic species Thespesia grandiflora. The microbes associated with these flowers are unknown and our objective was to isolate and characterize them. We collected flowers and inoculated pieces of petals, stigmas, pollen, and nectar, on potato dextrose agar. The bacteria isolated were cultured in potato dextrose broth with 0.15% tryptophan and tested for indole acetic acid (IAA) production using the Salkowski reagent. Absorbance was measured at 535 nm and compared to a standard curve. DNA was extracted from the microbial isolates, and the 16S rRNA or ITS genes were amplified using PCR. Sequences were analyzed in BLAST and phylogenetic trees were constructed using MEGA. We isolated a total of 50 microorganisms including 20 bacteria and 30 fungi. We identified 8 bacterial isolates that produce IAA, 5 that solubilize phosphate, and one with antifungal properties. Bacteria produced IAA between 67 µg/mL – 1 µg/mL. We isolated bacteria including Rosenbergiella and Leclercia from petals, Pantoea from a petal and stigma, and Acinetobacter isolated from nectar. The fungi Pestalotiopsis, Colletotrichum, Cladosporium, Penicillium, and Ciboria were isolated. Our research revealed that Maga flowers harbor microbes in different flower tissues, some of which have beneficial traits.These microorganisms can be important in the reproduction and health of this endemic species.