Department of Microbiology, Faculty of Science, Khon Kaen University, 123 Mittraphap Road, Nai-Muang, Muang District, Khon Kaen, 40002, Thailand.
Research Center for Environmental and Hazardous Substance Management, Khon Kaen University, Khon Kaen, 40002, Thailand.
BMC Plant Biol. 2024 Jul 15;24(1):672. doi: 10.1186/s12870-024-05352-6.
Grain quality is an important index of rice production, particularly when plants are grown under stress. Arsenic (As) contamination in paddy fields severely affects rice grain yield and quality. Here, the effects of As and combinations of As(III)-oxidizing bacteria (Pseudomonas stutzeri 4.25, 4.27, and 4.44) and plant growth-promoting bacteria (Delftia acidovorans KKU2500-12 and Cupriavidus taiwanensis KKU2500-3) on enzymes related to starch accumulation in grains and the grain quality of Khao Dawk Mali 105 rice cultivated in As-contaminated soil under greenhouse conditions were investigated.
Arsenic affected the activities of starch biosynthesis-related enzymes, and decreases of up to 76.27%, 71.53%, 49.74%, 73.39%, and 47.46% in AGPase, SSS, GBSS, SBE, and SDBE activities, respectively, and 9.42-61.07% in starch accumulation in grains were detected after growth in As-contaminated soil. However, the KKU2500-3/4.25 and KKU2500-3/4.44 combinations yielded the greatest enzyme activities in grains, and compared with the results observed in uninoculated seedlings, increases in starch accumulation of up to 51.16% and 23.81% were found in the inoculated seedlings after growth in medium- and high-As-contaminated soils, at 10-17 and 10-24 days after anthesis, respectively. The bacteria increased the 2-AP content in rice under As stress, possibly via the induction of proline, a 2-AP substrate. Bacterium-inoculated rice had significantly greater 2-AP levels than uninoculated rice, and 2.16-9.93% and 26.57-42.04% increases were detected in rice plants grown in medium- and high-As-contaminated soils, respectively.
Arsenic toxicity can be mitigated in rice growing under greenhouse conditions by maintaining starch biosynthesis, accumulating amylose, and increasing 2-AP content. The effectiveness of these bacteria should be validated in paddy fields; hence, safe rice grains with a good starch content and aroma could be produced.
谷物质量是稻米生产的一个重要指标，尤其是在植物受到胁迫时。稻田砷污染严重影响稻米的产量和品质。本研究采用砷（As）污染土壤温室盆栽试验，探讨了砷及其与砷氧化菌（恶臭假单胞菌 4.25、4.27 和 4.44）和植物促生菌（戴夫特氏菌 KKU2500-12 和铜绿假单胞菌 KKU2500-3）组合对水稻品种“Khao Dawk Mali 105”灌浆期籽粒淀粉积累相关酶活性及稻米品质的影响。
砷显著影响了籽粒淀粉合成相关酶活性，AGPase、SSS、GBSS、SBE 和 SDBE 活性分别下降 76.27%、71.53%、49.74%、73.39%和 47.46%，籽粒淀粉积累量下降 9.42%~61.07%。而砷污染土壤中种植的水稻，接种 KKU2500-3/4.25 和 KKU2500-3/4.44 组合后，灌浆期籽粒中各酶活性最高，与未接种的水稻相比，在中、高砷污染土壤中种植的水稻，在花后 10-17 天和 10-24 天，淀粉积累量分别增加了 51.16%和 23.81%。细菌在砷胁迫下增加了水稻 2-AP 含量，可能是通过诱导 2-AP 前体物质脯氨酸实现的。与未接种的水稻相比，接种细菌的水稻 2-AP 含量显著增加，在中、高砷污染土壤中种植的水稻分别增加了 2.16%-9.93%和 26.57%-42.04%。
温室条件下，通过维持淀粉合成、积累直链淀粉和增加 2-AP 含量，可减轻砷对水稻的毒害。这些细菌的有效性需要在稻田中进一步验证，从而生产出安全、具有良好淀粉含量和香气的稻米。
