Borch, K.; Bouma, T.J.; Lynch, J.P.; Brown, K.M.


Plant Cell & Environment, Volume 22, Issue 4, p.425-431 (1999)

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The involvement of ethylene in root architectural responses to phosphorus availability was investigated in common bean (Phaseolus vulgaris CIAT breeding line DOR364) plants grown in pots of silica sand in a greenhouse with sufficient or insufficient phosphorus (P). Although P deficiency reduced root mass and lateral root number, main root length was unchanged by P treatment. This resulted in decreased lateral root density in P-deficient plants. The possible involvement of ethylene in growth responses to P deficiency was investigated by inhibiting endogenous ethylene production with amino-ethoxyvinylglycine (AVG) and aerating the root system with various concentrations of ethylene. P deficiency doubled the root:shoot ratio, an effect which was suppressed by AVG and partially restored by exogenous ethylene. AVG increased lateral root density in P-deficient plants but reduced it in P-sufficient plants. These responses could be reversed by exogenous ethylene, suggesting ethylene involvement in the regulation of main root extension and lateral root spacing. P-deficient roots produced twice as much ethylene per gramme of dry matter as P-sufficient roots. Enhanced ethylene production and altered ethylene sensitivity in P-deficient plants may be responsible for root responses to P deficiency