open access

https://hdl.handle.net/2115/75995

Effects of co-inoculation of two different plant growth-promoting bacteria on duckweed

英語

Three-way symbiosis

2018-11

Springer

Plant growth regulation

86(2)

287-296

Aseptic Lemna minor was soaked for 4 h in pond water where wild L. minor was naturally flourishing. Seven of the eight surface-colonizing bacterial strains were found capable of promoting the growth of L. minor. This high appearance of plant growth-promoting bacteria (PGPB) suggests that association of environmental bacteria is generally beneficial rather than harmful for host plants. One of the PGPB, Pseudomonas sp. Ps6, enhanced the growth of L. minor by 2-2.5-fold in 10 days. This activity was higher than that previously reported for Acinetobacter calcoaceticus P23, which enhanced growth of L. minor by 1.5-2-fold. Ps6 mostly adhered to and colonized the root rather than the frond, a leaf-like structure of duckweed where P23 preferentially adheres. It was expected that these two strains can share niches, coexist, and enhance the growth of duckweed additively upon co-inoculation. However, contrary to expectation, the growth of L. minor was enhanced by only 2.3-fold by co-inoculation of these two bacteria. P23 lowered the initial adhesion of Ps6 cells by 98.2% on the fronds and by 79.5% on the roots. However, initial adhesion of P23 cells to the roots increased dramatically, by 47.2-fold, following co-inoculation with Ps6. However, the number of P23 cells decreased dramatically to 0.7% on the root and to 3.6% on the frond after 10 days, whereas Ps6 cells increased by 12.5-fold on the frond and kept 69% on the root, thereby eventually restoring the population on the plant surfaces. Because duckweed is the fastest growing vascular plant and it is easy to grow an aseptic and axenic plant, the duckweed/bacteria co-culture system will be a model platform for studying multiple interactions among host plants and the associated bacteria.

学術雑誌論文

Accepted Manuscript

The final publication is available at link.springer.com

0167-6903