Root exudates are known signaling agents that influence legume root nodulation, but the molecular mechanisms for nonflavonoid molecules remain largely unexplored. The number of soybean root nodules during the initial growth phase shows substantial discrepancies at distinct developmental junctures. Using a combination of metabolomics analyses on root exudates and nodulation experiments, we identify a pivotal role for certain root exudates during the rapid growth phase in promoting nodulation. Phenoxyacetic acid (POA) was found to activate the expression of GmGA2ox10 and thereby facilitate rhizobial infection and the formation of infection threads. Furthermore, POA exerts regulatory control on the miR172c-NNC1 module to foster nodule primordia development and consequently increase nodule numbers. These findings collectively highlight the important role of POA in enhancing nodulation during the accelerated growth phase of soybeans.

In molecular biology studies, suitable vectors are fundamental tools; however, most vectors can only express one target gene, which limits the ability to study multiple genes simultaneously within the same plant tissue. The traditional method for achieving multi-gene co-expression involves co-transferring multiple plasmids into plant tissues, but this approach is often inefficient due to the difficulty of successfully transforming multiple plasmids at once. To overcome this limitation, we have developed a series of vectors, called pMAGs (Multigene Assembly Genetic vectors), capable of simultaneously expressing or silencing two or three different genes in plants. These vectors not only provide an optimal solution for a wide range of biological experiments but also work effectively across numerous plant species.