Endophytic bacteria of Ficus microcarpa enhance rice root formation through phytohormone production

Abstract

Importance of the work: Endophytic bacteria play a crucial role in promoting plant growth and resilience through the production of phytohormones, offering promising applications in sustainable agriculture. Objectives: To isolate and characterize endophytic bacteria from the aerial roots of Ficus microcarpa L.f. and to evaluate their abilities to produce gibberellins (GAs) and indole-3-acetic acid (IAA), as well as their effects on the root development of rice seedlings. Materials and Methods: In total, 28 bacterial strains were isolated from the aerial roots, screened for IAA and GA production and identified through molecular techniques. Three promising isolates (Bacillus sp. LV34, Pantoea sp. CM21 and Rhizobium sp. TN43) were selected for inoculation on rice seedlings, with root growth parameters assessed after 9 d. Results: Bacillus sp. LV34 showed the highest IAA production (427.17 ± 16.59 µg/ mL), whereas Rhizobium sp. TN43 showed the highest GA production (179.99 ± 7.41 µg/mL). Inoculation with Bacillus sp. LV34 significantly increased both the number of roots (7.5 roots per plant on average) and total root length (450 mm) in the rice seedlings, with Rhizobium sp. TN43 and Pantoea sp. CM21 also promoting root growth to varying degrees. Main finding: The high phytohormone-producing endophytic bacteria isolated from Ficus microcarpa demonstrated notable potential to enhance plant growth, highlighting their applicability as biofertilizer candidates for sustainable crop management.