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A role for inositol hexakisphosphate in the maintenance of basal resistance to plant pathogens
Author(s) -
Murphy Alex M.,
Otto Bettina,
Brearley Charles A.,
Carr John P.,
Hanke David E.
Publication year - 2008
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2008.03629.x
Subject(s) - biology , tobacco mosaic virus , pseudomonas syringae , arabidopsis thaliana , mutant , cauliflower mosaic virus , virulence , microbiology and biotechnology , pathogen , botrytis cinerea , salicylic acid , cucumber mosaic virus , jasmonic acid , genetically modified crops , virus , virology , gene , biochemistry , transgene , plant virus , botany
Summary Phytic acid ( myo ‐inositol hexakisphosphate, Ins P 6 ) is an important phosphate store and signal molecule in plants. However, low‐phytate plants are being developed to minimize the negative health effects of dietary Ins P 6 and pollution caused by undigested Ins P 6 in animal waste. Ins P 6 levels were diminished in transgenic potato plants constitutively expressing an antisense gene sequence for myo ‐inositol 3‐phosphate synthase (IPS, catalysing the first step in Ins P 6 biosynthesis) or Escherichia coli polyphosphate kinase. These plants were less resistant to the avirulent pathogen potato virus Y and the virulent pathogen tobacco mosaic virus (TMV). In Arabidopsis thaliana , mutation of the gene for the enzyme catalysing the final step of Ins P 6 biosynthesis (Ins P 5 2‐kinase) also diminished Ins P 6 levels and enhanced susceptibility to TMV and to virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae . Arabidopsis thaliana has three IPS genes ( AtIPS1 – 3 ). Mutant atips2 plants were depleted in Ins P 6 and were hypersusceptible to TMV, turnip mosaic virus, cucumber mosaic virus and cauliflower mosaic virus as well as to the fungus Botrytis cinerea and to P. syringae . Mutant atips2 and atipk1 plants were as hypersusceptible to infection as plants unable to accumulate salicylic acid (SA) but their increased susceptibility was not due to reduced levels of SA. In contrast, mutant atips1 plants, which were also depleted in Ins P 6 , were not compromised in resistance to pathogens, suggesting that a specific pool of Ins P 6 regulates defence against phytopathogens.