Atia Abdallah, Debez Ahmed, Barhoumi Zouhaier, Smaoui Abderrazak, Abdelly Chedly
Centre de biotechnologie à la technopole de Borj Cedria, Hammam-Lif, Tunisia.
C R Biol. 2009 Aug;332(8):704-10. doi: 10.1016/j.crvi.2009.03.009. Epub 2009 May 8.
Impaired germination is common among halophyte seeds exposed to salt stress, partly resulting from the salt-induced reduction of the growth regulator contents in seeds. Thus, the understanding of hormonal regulation during the germination process is a main key: (i) to overcome the mechanisms by which NaCl-salinity inhibit germination; and (ii) to improve the germination of these species when challenged with NaCl. In the present investigation, the effects of ABA, GA(3), NO(-)(3), and NH(+)(4) on the germination of the oilseed halophyte Crithmum maritimum (Apiaceae) were assessed under NaCl-salinity (up to 200 mM NaCl). Seeds were collected from Tabarka rocky coasts (N-W of Tunisia). The exogenous application of GA(3), nitrate (either as NaNO(3) or KNO(3)), and NH(4)Cl enhanced germination under NaCl salinity. The beneficial impact of KNO(3) on germination upon seed exposure to NaCl salinity was rather due to NO(-)(3) than to K(+), since KCl failed to significantly stimulate germination. Under optimal conditions for germination (0 mM NaCl), ABA inhibited germination over time in a dose dependent manner, but KNO(3) completely restored the germination parameters. Under NaCl salinity, the application of fluridone (FLU) an inhibitor of ABA biosynthesis, stimulated substantially seed germination. Taken together, our results point out that NO(-)(3) and GA(3) mitigate the NaCl-induced reduction of seed germination, and that NO(-)(3) counteracts the inhibitory effect of ABA on germination of C. maritimum.
在暴露于盐胁迫的盐生植物种子中，发芽受损很常见，部分原因是盐诱导种子中生长调节物质含量降低。因此，了解发芽过程中的激素调节是关键所在：（i）克服NaCl盐度抑制发芽的机制；（ii）在NaCl胁迫下提高这些物种的发芽率。在本研究中，评估了脱落酸（ABA）、赤霉素（GA₃）、硝酸根（NO₃⁻）和铵根（NH₄⁺）对盐生油料植物滨海刺芹（伞形科）在NaCl盐度（高达200 mM NaCl）下种子萌发的影响。种子采自突尼斯西北的塔巴卡岩石海岸。外源施用GA₃、硝酸盐（NaNO₃或KNO₃）和NH₄Cl可提高NaCl盐度下的发芽率。种子暴露于NaCl盐度时，KNO₃对发芽的有益影响主要归因于NO₃⁻而非K⁺离子，因为KCl未能显著刺激发芽。在最佳发芽条件（0 mM NaCl）下，ABA随时间以剂量依赖性方式抑制发芽，但KNO₃完全恢复了发芽参数。在NaCl盐度下，施用脱落酸生物合成抑制剂氟啶酮（FLU）可显著刺激种子发芽。综上所述，我们的结果表明，NO₃⁻和GA₃可减轻NaCl诱导的种子发芽率降低，且NO₃⁻可抵消ABA对滨海刺芹种子发芽的抑制作用。
