Endophytic bacteria of Ficus microcarpa L.f. 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.