The auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) inhibits the stimulation of in vitro lateral root formation and the colonization of the tap-root cortex of Norway spruce (Picea abies) seedlings by the ectomycorrhizal fungus Laccaria bicolor
The auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) inhibits the stimulation of in vitro lateral root formation and the colonization of the tap-root cortex of Norway spruce (Picea abies) seedlings by the ectomycorrhizal fungus Laccaria bicolor
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DOI：
10.1046/j.1469-8137.1998.00307.x
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发表时间：
1998-12-01
期刊：
影响因子：
9.4
通讯作者：
Le Tacon, F
中科院分区：
文献类型：
--
作者：
Karabaghli-Degron, C;Sotta, B;Le Tacon, F
挪威云杉（Picea abies（L.）喀斯特）。在无菌条件下，用外生菌根真菌双色蜡蘑（（玛丽）奥顿），菌株S238 N接种幼苗。真菌的存在下，接种后的第一个15天内，减缓了26%的主根伸长，然后刺激它的136%。此外，它还使离体侧根形成增加4.3倍，幼苗上胚轴生长增加8.4倍，针叶数增加2倍。当真菌与根通过玻璃纸膜分离以防止共生建立时，这些效果得以维持，从而表明真菌通过非营养效应起作用。我们验证了L. bicolor S238 N可能是促进真菌诱导生根的主要原因。我们在以前的工作中表明，L。Bicolor S238 N在纯培养中能合成IAA。外源IAA供应（100和500亩M）再现的真菌对根分枝的刺激作用，但抑制根伸长。培养基中添加2，3，5-三碘苯甲酸（TIBA）可显著抑制接种苗侧根的形成。由于TIBA对L. TIBA对Bicolor S238 N的生根有抑制作用，但对外源IAA诱导的侧根发生有抑制作用，说明TIBA抑制了真菌IAA在根中的运输。此外，TIBA还能阻断L. bicolor S238 N和Hartig网的形成。这些结果说明了真菌IAA在刺激侧根发生和建立外生菌根共生关系中的作用。
Norway spruce (Picea abies (L.) Karst.) seedlings were inoculated with the ectomycorrhizal fungus Laccaria bicolor ((Marie) Orton), strain S238 N, in axenic conditions. The presence of the fungus slowed tap-root elongation by 26 % during the first 15 d after inoculation and then stimulated it by 136 %. In addition, it multiplied in vitro lateral root formation by 4.3, the epicotyl growth of the seedlings by 8.4 and the number of needles by 2. These effects were maintained when the fungus was separated from the roots by a cellophane membrane preventing symbiosis establishment, thus suggesting that the fungus acted by non-nutritional effects. We tested the hypothesis that IAA produced by L. bicolor S238 N would be responsible for the stimulation of fungal induced rhizogenesis. We showed in previous work that L. bicolor S238 N can synthesize IAA in pure culture. Exogenous IAA supplies (100 and 500 mu M) reproduced the stimulating effect of the fungus on root branching but inhibited root elongation. The presence of 2,3,5-triiodobenzoic acid (TIBA) in the culture medium significantly depressed lateral root formation of inoculated seedlings. As TIBA had no significant effect on IAA released in the medium by L. bicolor S238 N, but counteracted the stimulation of lateral rhizogenesis induced by an exogenous supply of IAA, we suggest that TIBA inhibited the transport of fungal IAA in the root. Furthermore TIBA blocked the colonization of the main root cortex by L. bicolor S238 N and the formation of the Hartig net. These results specified the role of fungal IAA in the stimulation of lateral rhizogenesis and in ectomycorrhizal symbiosis establishment.