Knockdown of confers strigolactones mediated rhizobia interaction and promotes nodulation in soybean.

Background: Strigolactones (SLs) play a key role in modulating plant root growth, shoot branching, and plant-symbiont interaction. However, despite their significance, the components of SL biosynthesis and signaling in soybean and their role in soybean-rhizobia interaction is unknown.

Methods: In this study, we identified and functionally characterized the from soybean. The ORFs were amplified from root cDNA using primers for RNA interference. To induce transgenic hairy roots of soybean, electric shock was used to transform pB7WG1WG2 vectors containing knockdown and into strains of . The hairy roots and nodules were collected and examined for root nodules ratio and RNA was extracted after 4 weeks of rhizobia inoculation.

Results: A tissue-specific expression assay showed that was differentially expressed in plant parts, predominantly in the stem and nodule. Furthermore, its expression was significantly up-regulated during rhizobia infection and varied with nodule formation. The -knockdown chimerical plants were produced to further check its role in soybean nodulation in comparison with control . In knockdown lines, the (suppressor of strigolactone MAX2) has a higher number of nodules compared to control lines. Furthermore, the expression levels of several nodulation genes essential for initiation and formation of nodules were altered in -knockdown lines.

Conclusion: The results revealed that SL biosynthesis and signaling are not conserved but also have close interaction between SL and legume rhizobia.