title: An underground tale: contribution of microbial activity to plant iron acquisition via ecological processes.
abstract: BACKGROUND
  Iron (Fe) deficiency in crops is a worldwide agricultural problem. Plants have evolved several strategies to enhance Fe acquisition, but increasing evidence has shown that the intrinsic plant-based strategies alone are insufficient to avoid Fe deficiency in Fe-limited soils. Soil micro-organisms also play a critical role in plant Fe acquisition; however, the mechanisms behind their promotion of Fe acquisition remain largely unknown.
  
  
  METHODS
  This review focuses on the possible mechanisms underlying the promotion of plant Fe acquisition by soil micro-organisms.
  
  
  CONCLUSIONS
  Fe-deficiency-induced root exudates alter the microbial community in the rhizosphere by modifying the physicochemical properties of soil, and/or by their antimicrobial and/or growth-promoting effects. The altered microbial community may in turn benefit plant Fe acquisition via production of siderophores and protons, both of which improve Fe bioavailability in soil, and via hormone generation that triggers the enhancement of Fe uptake capacity in plants. In addition, symbiotic interactions between micro-organisms and host plants could also enhance plant Fe acquisition, possibly including: rhizobium nodulation enhancing plant Fe uptake capacity and mycorrhizal fungal infection enhancing root length and the nutrient acquisition area of the root system, as well as increasing the production of Fe(3+) chelators and protons.
authors.affiliation: College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Chong Wei
authors.initials: CW
authors.lastname: Jin
authors.forename: Yi Quan
authors.initials: YQ
authors.lastname: Ye
authors.forename: Shao Jian
authors.initials: SJ
authors.lastname: Zheng
mesh_terms: D007501:Iron / Q000378:metabolism* / Q000493:pharmacokinetics; D038821:Mycorrhizae; D018517:Plant Roots / Q000378:metabolism* / Q000382:microbiology*; D010944:Plants / Q000378:metabolism*; D058441:Rhizosphere; D017262:Siderophores; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D017262:Siderophores; D007501:Iron
keywords: Hormones; iron deficiency; microbial community structure; siderophore; symbiosis