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Physiological characterization and genetic modifiers of aberrant root thigmomorphogenesis in mutants of A rabidopsis thaliana MILDEW LOCUS O genes
Author(s) -
BIDZINSKI PRZEMYSLAW,
NOIR SANDRA,
SHAHI SHERMINEH,
REINSTÄDLER ANJA,
GRATKOWSKA DOMINIKA MARTA,
PANSTRUGA RALPH
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12353
Subject(s) - gravitropism , biology , auxin , mutant , root hair , arabidopsis thaliana , polar auxin transport , root cap , lateral root , microbiology and biotechnology , botany , arabidopsis , gene , genetics , meristem
Root architecture and growth patterns are plant features that are still poorly understood. When grown under in vitro conditions, seedlings with mutations in A rabidopsis thaliana genes MLO 4 or MLO 11 exhibit aberrant root growth patterns upon contact with hard surfaces, exemplified as tight root spirals. We used a set of physiological assays and genetic tools to characterize this thigmomorphogenic defect in detail. We observed that the mlo4 / mlo11 ‐associated root curling phenotype is not recapitulated in a set of mutants with altered root growth patterns or architecture. We further found that mlo4 / mlo11 ‐conditioned root curling is not dependent upon light and endogenous flavonoids, but is pH ‐sensitive and affected by exogenous calcium levels. Based upon the latter two characteristics, mlo4 ‐associated root coiling appears to be mechanistically different from the natural strong root curvature of the A rabidopsis ecotype L andsberg erecta . Gravistimulation reversibly overrides the aberrant thigmomorphogenesis of mlo4 seedlings. Mutants with dominant negative defects in α ‐tubulin modulate the extent and directionality of mlo4 / mlo11 ‐conditioned root coils, whereas mutants defective in polar auxin transport ( axr4 , aux1 ) or gravitropism ( pgm1 ) completely suppress the mlo4 root curling phenotype. Our data implicate a joint contribution of calcium signalling, pH regulation, microtubular function, polar auxin transport and gravitropism in root thigmomorphogenesis.