Enhancement of the Aroma Compound 2-Acetyl-1-pyrroline in Thai Jasmine Rice (Oryza sativa) by Rhizobacteria under Salt Stress

Abstract

Thai jasmine rice (Oryza sativa L. KDML105), particularly from inland salt-affected areas in Thailand, is both domestically and globally valued for its unique aroma and high grain quality. The key aroma compound, 2-acetyl-1-pyrroline (2AP), has undergone a gradual degradation due to anthropogenic soil salinization driven by excessive chemical input and climate change. Here, we propose a cheaper and an ecofriendly solution to improve the 2AP levels, based on the application of plant growth-promoting rhizobacteria (PGPR). In the present study, nine PGPR isolates from rice rhizosphere were investigated for the 2AP production in liquid culture and the promotion potential for 2AP content in KDML105 rice seedlings under four NaCl concentrations (0, 50, 100, and 150 mM NaCl). The inoculation of 2AP-producing rhizobacteria resulted in an increase in 2AP content in rice seedling leaves with the maximum enhancement from Sinomonas sp. ORF15-23 at 50 mM NaCl (19.6 µg·kg−1), corresponding to a 90.2% increase as compared to the control. Scanning electron microscopy confirmed the colonization of Sinomonas sp. ORF15-23 in the roots of salinity-stressed KDML105 seedlings. Our results provide evidence that Sinomonas sp. ORF15-23 could be a promising PGPR isolate in promoting aroma level of Thai jasmine rice KDML105 under salt stress.

Optimization of enzymatic hydrolysis by alcalase and flavourzyme to enhance the antioxidant properties of jasmine rice bran protein hydrolysate

“…The characteristic of jasmine rice, known its for long grain, tender texture and sweet-scented aroma. The major aroma compound of jasmine rice has been identified as 2-acetyl-1-pyrroline (2AP) that a perceived criteria for good quality rice 2 . The composition of rice bran provides about 14.7% protein, 20.9% fat, 52.3% carbohydrate and some other components 1 .…”

Isolation and characterization of KDML105 aromatic rice rhizobacteria producing indole‐3‐acetic acid: impact of organic and conventional paddy rice practices

“…in the stem (Koomnok et al 2007;Mano and Morisaki 2008); and Bacillus sp., Bukholderia sp., Herbaspirillum sp., Klebsiella sp., Methylobacterium sp., and Novosphingobium sp. in the roots (Verma et al 2004;Mano and Morisaki 2008;Chinachanta et al 2021). The literature has described many plant hormones, also called phytohormones, but there are 5 main classes: auxins, cytokinins, gibberellins, abscisic acid and ethylene.…”

Rhizoactinobacteria Enhance Growth and Antioxidant Activity in Thai Jasmine Rice (Oryza sativa) KDML105 Seedlings under Salt Stress

“…Nine KDML105 rice rhizobacterial strains that exhibited various degrees of tolerance to high salt concentrations (0 to 3% NaCl) were selected from our previous study [16] to evaluate their effects on KDML105 rice seedlings' growth and salt tolerance. All of the strains were able to produce IAA and promote the production of 2AP in KDML105 rice seedlings under salt stress.…”

“…In the present investigation, we hypothesized that the inoculation of ST-PGPR obtained from the KDML105 rice rhizosphere grown in the TKR region would enhance the growth, salt tolerance, and aroma intensity of the KDML105 variety. Therefore, IAAproducing ST-PGPR strains previously screened by our group [16,17] were used in the present study. Firstly, the 2AP production potential in the culture broth of the ST-PGPR strains was selected [16], and the selected strains were then used to inoculate KDML105 rice seedlings.…”

“…Therefore, IAAproducing ST-PGPR strains previously screened by our group [16,17] were used in the present study. Firstly, the 2AP production potential in the culture broth of the ST-PGPR strains was selected [16], and the selected strains were then used to inoculate KDML105 rice seedlings. The objective of the present study was to evaluate the effects of ST-PGPR strains on growth parameters, chlorophyll content, nutrient concentration, antioxidant capacity, and proline concentrations in the rice seedlings germinated under different levels of salinity.…”