Author(s):

Nasreen Fatima, Kousar Javaid, Kunzang Lahmo, Saba Banday, Dr. Poonam Sharma and Lubna Masoodi

Abstract: The iron plays free catalytic role in various vital cellular reactions and is not freely available in the environment due to host sequestration Maintaining the appropriate balance of iron between deficiency and toxicity requires fixed tuned-control system for iron uptake and storage. Most fungi express specific mechanism for acquisition of iron from the hosts they infect for their own survival. Siderophores, a low molecular weight iron chelator has the ability to form very stable and soluble complexes with iron. High affinity iron uptake systems such as siderophores mediated iron uptake and reductive iron assimilation (RIA) enable fungi to acquire limited iron from plant and animal host. Regulating the iron uptake is crucial to maintain iron homeostasis, a state necessary to avoid iron toxicity from iron abundance and simultaneously supply iron required to meet biochemical demand. Fungal cell used two different strategies to regulate iron acquisition that are activation during iron starvation and repression during iron deplete condition. Siderophores play diverse role in fungal host interaction, many of which have been delineated from gene deletion in NRPS, enzyme required for virulence, resistance to oxidative stresses, asexual/sexual development, iron storage and protection against iron induced toxicity in some fungal organism. It is demonstrated that fungal cell siderophores are virulence determinant. Cochliobolus heterostrophus NPS₆ deletion result in a strain that in reduced in virulence to corn and NPS6 deletion in C. miyabeanus, F. gramineasum and A. brassiciola also causes a reduction in pathogenicity to rice, wheat and Arabidopsis, respectively. Recently siderophores have been reported to play roles in plant-fungus symbioses.

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