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Empowering rice seedling growth by endophytic Bradyrhizobium sp. SUTN 9‐2
Author(s) -
Greetatorn T.,
Hashimoto S.,
Sarapat S.,
Tittabutr P.,
Boonkerd N.,
Uchiumi T.,
Teaumroong N.
Publication year - 2019
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.13114
Subject(s) - seedling , biology , nitrogen fixation , endophyte , dry weight , inoculation , azospirillum brasilense , horticulture , bradyrhizobium , botany , agronomy , bacteria , microbial inoculant , genetics , rhizobium
Bradyrhizobium sp. strain SUTN 9‐2 was confirmed as rice endophytic bacteria and also as rice growth promotion agent. SUTN 9‐2 showed the capability of plant growth promotion characteristics, such as indole‐3‐acetic acid ( IAA ) and 1‐amino‐cyclopropane‐1‐carboxylic acid ( ACC ) deaminase productions and nitrogen fixation. In this study, the ability of SUTN 9‐2 to stimulate rice growth was investigated at different stages with N‐free and NH 4 NO 3 under in vivo condition. The rice dry weight and chlorophyll content could be enhanced when SUTN 9‐2 was inoculated in N‐free, especially at seedling stage (7 and 14 dai). The rice dry weight was also increased when SUTN 9‐2 was inoculated with NH 4 NO 3 at 7 and14 dai. The results of quantitative analysis of IAA and ACC deaminase were inconsistent with the expression of genes involved in IAA ( nit ) and ACC deaminase ( acdS ) productions. This inconsistently could implied that IAA and ACC deaminase produced from SUTN 9‐2 do not directly affect rice growth, but other factors resulting from the production of IAA and ACC deaminase could be involved. Moreover, the expression of genes involved in nitrogen fixation ( nifH and nifV ) of SUTN 9‐2 was also induced in rice tissues. This finding suggested that rice growth promotion may be supported by NH 4 NO 3 together with nitrogen fixation by SUTN 9‐2. Significance and Impact of the Study Indole‐3‐acetic acid, 1‐amino‐cyclopropane‐1‐carboxylic acid deaminase productions and nitrogen fixation may play important roles in rice growth promotion by endophytic SUTN 9‐2, especially at early rice seedling growth stage, which has the potential to be used as rice seedling growth promoter in the system of rice intensification.