Amelioration of the salt-stressed root growth of rice and normalization of the Na+ distribution between the shoot and root by (S)-alpha-methylbenzyl-2-fluoro-4-methylphenylurea.
Optically active alpha-methylbenzyl phenyl ureas (MBPUs) show diverse plant physiological properties. Experiments were conducted to evaluate the salt-stress response of just-germinated rice seedlings supplemented with the S-enantiomer of MBPUs by assessing the growth and Na+ content. This study indicates that S-MBPUs served as a unique stress reliever for just-germinated young seedlings of rice injured by salinity. NaCl severely affected the root growth of rice seedlings. Concomitant treatment with S-MBPUs effectively ameliorated the growth inhibition of rice by NaCl. Glycine betaine (GB) did not act as a reliever of the NaCl stress. The addition of S-alpha-methylbenzyl 2-fluoro-4-methylphenyl urea (7, denoted as S-FM) to the saline medium ameliorated not only the root growth but also the protein content and dry weight of roots depending upon its concentration. The protein content, Na+ content and growth rate were correlated to each other with a positive relationship. The Na+ distribution ratio (S/R(Na+)) between the shoot and root increased with increasing concentration of NaCl when added alone, viz. with increasing growth reduction. A concomitant treatment with S-FM (7), however, resulted in the S/R(Na+) value becoming smaller with growth amelioration. This indicates that S-FM (7) controlled the translation of Na+ from the roots to shoots. S-FM (7) would have influenced some inherent functions connected with the Na+ behavior in the rice plant, although details of the mechanism for normalization of the S/R(Na+) ratio are still not clear.
Omokawa
Hiroyoshi
H
Center for Research on Wild Plants, Utsunomiya University, Mine, Japan. omokawa@cc.utsunomiya-u.ac.jp
Aonuma
Shin-ichi
S
D012275:Oryza / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010671:Phenylurea Compounds / Q000494:pharmacology*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects* / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology*
D010671:Phenylurea Compounds; D010940:Plant Proteins; C467713:alpha-methylbenzyl-2-fluoro-4-methylphenylurea; D012965:Sodium Chloride