Paenibacillus polymyxa BFKC01 enhances plant iron absorption via improved root systems and activated iron acquisition mechanisms.
Despite the high abundance of iron (Fe) in most earth's soils, Fe is the major limiting factor for plant growth and development due to its low bioavailability. With an increasing recognition that soil microbes play important roles in plant growth, several strains of beneficial rhizobactria have been applied to improve plant nutrient absorption, biomass, and abiotic or biotic stress tolerance. In this study, we report the mechanisms of microbe-induced plant Fe assimilation, in which the plant growth promoting rhizobacteria (PGPR) Paenibacillus polymyxa BFKC01 stimulates plant's Fe acquisition machinery to enhance Fe uptake in Arabidopsis plants. Mechanistic studies show that BFKC01 transcriptionally activates the Fe-deficiency-induced transcription factor 1 (FIT1), thereby up-regulating the expression of IRT1 and FRO2. Furthermore, BFKC01 has been found to induce plant systemic responses with the increased transcription of MYB72, and the biosynthetic pathways of phenolic compounds are also activated. Our data reveal that abundant phenolic compounds are detected in root exudation of the BFKC01-inoculated plants, which efficiently facilitate Fe mobility under alkaline conditions. In addition, BFKC01 can secret auxin and further improved root systems, which enhances the ability of plants to acquire Fe from soils. As a result, BFKC01-inoculated plants have more endogenous Fe and increased photosynthetic capacity under alkaline conditions as compared to control plants. Our results demonstrate the potential roles of BFKC01 in promoting Fe acquisition in plants and underline the intricate integration of microbial signaling in controlling plant Fe acquisition.
Key Laboratory of Bio-organic Fertilizer Creation, Ministry of Agriculture, Institute for Applied Microbiology, Anhui Science and Technology University, Bengbu 233100, China.
Cheng
C
Zhou
School of Medicine, Zhejiang University, Hangzhou 310058, China.
Jiansheng
J
Guo
Department of Molecular and Cell Biology, Tongji University, Shanghai 200092, China.
Lin
L
Zhu
Key Laboratory of Bio-organic Fertilizer Creation, Ministry of Agriculture, Institute for Applied Microbiology, Anhui Science and Technology University, Bengbu 233100, China.
Xin
X
Xiao
Key Laboratory of Bio-organic Fertilizer Creation, Ministry of Agriculture, Institute for Applied Microbiology, Anhui Science and Technology University, Bengbu 233100, China.
Yue
Y
Xie
Department of Molecular and Cell Biology, Tongji University, Shanghai 200092, China.
Jian
J
Zhu
Key Laboratory of Bio-organic Fertilizer Creation, Ministry of Agriculture, Institute for Applied Microbiology, Anhui Science and Technology University, Bengbu 233100, China. Electronic address: mazy@ahstu.edu.cn.
Zhongyou
Z
Ma
Key Laboratory of Bio-organic Fertilizer Creation, Ministry of Agriculture, Institute for Applied Microbiology, Anhui Science and Technology University, Bengbu 233100, China. Electronic address: wangjf@ahstu.edu.cn.
Jianfei
J
Wang
D065567:Absorption, Physiological; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure; D060467:Disease Resistance; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D000090463:Iron Deficiencies; D000070057:Paenibacillus polymyxa / Q000502:physiology*; D010636:Phenols / Q000378:metabolism; D010788:Photosynthesis; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology* / Q000648:ultrastructure; D060888:Real-Time Polymerase Chain Reaction; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010636:Phenols; D002734:Chlorophyll; D007501:Iron; D005966:Glucuronidase
Calcareous soils; Iron deficiency; Paenibacillus polymyxa; Phenolic compounds; Soil microbes