Paper Type |
Contributed Paper |
Title |
Isolation and Selection of Plant Growth Promoting Endophytic Bacteria Associated with Healthy Hevea brasiliensis for Use as Plant Growth Promoters in Rubber Seedlings under Salinity Stress |
Author |
Kulwadee Khotchanalekha [a], Weerasak Saksirirat [b], Supat Isarangkool Na Ayutthaya [c], Kenji Sakai [d], Yukihiro Tashiro [d], Yuki Okugawa[d] and Saowanit Tongpim*[a] |
Email |
saoton@kku.ac.th |
Abstract: Endophytic bacteria are defined as microorganisms that live in plant tissues for the whole or
part of their lives without causing adverse effect on the host plant. Bacterial endophytes have been
reported as plant growth promoters in several kinds of plants under normal and stress conditions.
The aims of this study were to isolate plant growth-promoting endophytic bacteria from healthy Para
rubber trees (Hevea brasiliensis) and investigate their effects on the growth of Para rubber seedlings grown
under salinity stress. Among the 415 endophytic isolates obtained, isolates AP6A3 and ER212 were
chosen for in vivo study under greenhouse conditions. Isolate AP6A3 produced a phytohormone indole
acetic acid (IAA) at 58.39 μg/ml and ACC deaminase; it was able to fix nitrogen, having a nitrogenase
activity at 64.14 μmol C2H4/tube/h determined using acetylene reduction assay but could not solubilize
inorganic phosphate. Isolate ER212 strongly solubilized tricalcium phosphate and released soluble
phosphate at 197.01 μg/ml; it produced only trace amounts of IAA, was absent of ACC deaminase
and did not fix nitrogen. Isolates AP6A3 and ER212 tolerated salinity well, at least 7% and 10% NaCl,
respectively. Characterization of these two isolates by conventional methods displayed that isolates
AP6A3 and ER212 belonged to the genus Enterobacter and Bacillus, respectively. These two endophytes
were then employed in greenhouse experiments with Para rubber seedlings grown under salinity stress
(500 mM NaCl). Interestingly, both endophytic isolates significantly enhanced the growth (based on
shoot height, stem diameter, root length, fresh and dry weight) of Para rubber seedlings when compared
to the un-inoculated seedlings. These results demonstrated that the endophytic Enterobacter sp. strain
AP6A3 and Bacillus sp. strain ER212 had a potential application as bio-fertilizer for plants grown in
saline environments. |
|
Start & End Page |
39 - 48 |
Received Date |
2019-08-14 |
Revised Date |
|
Accepted Date |
2019-10-04 |
Full Text |
Download |
Keyword |
endophyte, plant growth, Para rubber, seedling, salt stress |
Volume |
Vol.47 No.1 (January 2020) |
DOI |
|
SDGs |
|
View:697 Download:443 |