In vitro biological activity of metabolic extracts of wild and cultivated species of the genus Polianthes

Evelyn Y. Garcia-Ochoa graduated as Biotechnology Engineer from the Universidad Autónoma de Guadalajara, Mexico. She is currently a student of the Master's Degree in Floriculture Sciences at the Center for Research and Assistance in Technology and Design of the State of Jalisco, A.C. (CIATEJ), Mexico, where she collaborates on the project 258866 supported by SEP CONACYT CB-2015-01 for the genetic improvement and flowering in Polianthes, under the supervision of Dr. Ernesto Tapia. Tuberose (Polianthes tuberosa) is the most well-known species of the genus. The remaining wild species have been little studied and might possess useful plant secondary metabolites (SM). As part of her thesis research, she extracted methanol from bulbs of cultivars and wild species of Polianthes, and related Manfreda, and Prochnyanthes mexicana. Her objective was to evaluate their in vitro antimicrobial activity against the Tuberose phytopathogens, Dickeya dadantii and Pseudomonas aeruginosa. The bioassays were performed in vitro using disc diffusion (Kirby-Bauer method). The objective was to evaluate the percentage of inhibition of methanolic crude extracts with respect to antibiotic control. The tested extracts inhibited the growth of P. aeruginosa. The Prochnyanthes extract showed the greatest antibacterial activity, with 24±2.34% inhibition. Prochnyanthes tuberosa and P. pringlei also showed satisfactory results with values of 19.61±2.09% and 16.51±1.7%, at a concentration of 50 mg mL-1. The extracts effective against D. dadantii were P. pringlei (PI = 21.8±2.39%), Prochnyanthes (PI = 15.5±0.86%) and P. montana (PI = 9±1.16%) at concentrations of 50 mg mL-1, and Manfreda sp. (PI = 14.4±1.7%) at a concentration of 100 mg mL-1. Evelyn’s research showed that the methanolic extract of the P. tuberosa cultivar had bioactive activity only against P. aeruginosa, while the extract from P. pringlei and Prochnianthes mexicana showed the highest antibacterial activity. Manfreda sp. showed less inhibitory effect against either pathogen. She concluded that the differences in antibacterial activity of the crude extracts might be due to the nature and abundance of secondary metabolites accumulated in the bulb of the tested species. This study provided the basis for characterization of SM in bulbs of commercial cultivars and wild species from Polianthes with antibacterial activity. The candidates that produced the best extract from this testing would be: P. pringlei, Prochnianthes mexicana and P. tuberosa.

Evelyn Y. Garcia-Ochoa won the ISHS Young Minds Award for the best poster at the IX International Symposium on New Ornamental Crops in Mexico in September-October 2019.

Evelyn Y. Garcia-Ochoa, CIATEJ, Camino Arenero 1227, El Bajío, 45019 Zapopan, Jalisco, 45019, Mexico, e-mail: evelyn_yiri710@hotmail.com

The article is available in Chronica Horticulturae