AUTHOR=Zhao Catherine Z. , Huang Jian , Gyaneshwar Prasad , Zhao Dazhong 

TITLE=Rhizobium sp. IRBG74 Alters Arabidopsis Root Development by Affecting Auxin Signaling

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.02556

DOI=10.3389/fmicb.2017.02556

ISSN=1664-302X

ABSTRACT=<p><italic>Rhizobium</italic> sp. IRBG74 not only nodulates <italic>Sesbania cannabina</italic> but also can enhance rice growth; however, the underlying molecular mechanisms are not clear. Here, we show that <italic>Rhizobium</italic> sp. IRBG74 colonizes the roots of <italic>Arabidopsis thaliana</italic>, which leads to inhibition in the growth of main root but enhancement in the formation of lateral roots. The promotion of lateral root formation by <italic>Rhizobium</italic> sp. IRBG74 in the <italic>fls2-1</italic> mutant, which is insensitive to flagellin, is similar to the wild-type plant, while the auxin response deficient mutant <italic>tir1-1</italic> is significantly less sensitive to <italic>Rhizobium</italic> sp. IRBG74 than the wild type in terms of the inhibition of main root elongation and the promotion of lateral root formation. Further transcriptome analysis of <italic>Arabidopsis</italic> roots inoculated with <italic>Rhizobium</italic> sp. IRBG74 revealed differential expression of 50 and 211 genes at 24 and 48 h, respectively, and a majority of these genes are involved in auxin signaling. Consistent with the transcriptome analysis results, <italic>Rhizobium</italic> sp. IRBG74 treatment induces expression of the auxin responsive reporter <italic>DR5:GUS</italic> in roots. Our results suggest that in <italic>Arabidopsis Rhizobium</italic> sp. IRBG74 colonizes roots and promotes the lateral root formation likely through modulating auxin signaling. Our work provides insight into the molecular mechanisms of interactions between legume-nodulating rhizobia and non-legume plants.</p>