脱落酸对丛枝菌根真菌侵染和产孢的调控效应研究

The regulatory effect of abscisic acid on colonization and sporulation of arbuscular mycorrhizal fungus

摘要:

[目的] 揭示脱落酸（ABA）对丛枝菌根（AM）真菌侵染和产孢的影响，建立利用外源ABA促进孢子产量的高效菌剂扩繁方法。[方法] 利用番茄毛状根和AM真菌Rhizophagus irregularis DAOM 197198建立双重培养体系，通过外源施用ABA、赤霉素（GA）或者使用ABA、GA的缺陷突变体，染色观察菌根侵染，荧光定量PCR测定丛枝发育和脂质合成运输相关基因的表达，统计丛枝和孢子的数量，从而揭示ABA对AM真菌侵染和产孢的影响。[结果] ABA缺陷突变体not中的F%（侵染频率）、a%（丛枝丰度）、丛枝数量，以及丛枝发育特异性相关基因EXO70A1-like（LOC101253481）、脂质合成运输相关基因RAM2和STR2的表达均显著低于其野生型MT；外源施用ABA显著促进了F%、M%（侵染强度）、丛枝数量、孢子产量，以及脂质合成运输相关基因RAM2和STR2的表达，外源添加ABA处理的孢子产量约为不添加处理的4.5倍；外源GA处理极显著抑制了菌根侵染的所有指标和孢子产量；GA缺陷突变体gib3与其野生型MM的AM真菌侵染之间没有显著差异，但gib3的孢子产量显著高于MM。[结论] ABA通过促进脂质的合成和运输，提高AM真菌的侵染和丛枝形成，进而增加AM真菌的孢子产量。

Abstract:

[Objective] To reveal the effects of abscisic acid (ABA) on the colonization and sporulation of arbuscular mycorrhiza (AM) fungi, and to establish a highly efficient propagation methods by promoting spore production with exogenous ABA. [Methods] We established the dual culture system with tomato hairy roots and AM fungus Rhizophagus irregularis DAOM 197198, and the exogenous ABA and gibberellin (GA) were applied, or the deficient mutants of ABA and GA were employed. The mycorrhizal colonization was observed after staining, the expression of genes involved in the development of arbuscules and the synthesis and transfer of lipids were measured with qRCR, and the numbers of arbuscules and spores were counted, in order to reveal the effects of ABA on the colonization and sporulation of AM fungus. [Results] In the ABA-deficient mutant not, F% (mycorrhizal frequency), a% (arbuscular abundance), number of arbuscules, and the expression of arbuscule development-specific gene EXO70A1-like (LOC101253481) and the lipid synthesis and transfer related genes RAM2 and STR2 were significantly lower than those in the wild-type MT. Exogenous application of ABA significantly promoted F%, M% (mycorrhizal intensity), number of arbuscules, spore production, and the expression of RAM2 and STR2. The spore production applied with exogenous ABA was approximately 4.5 times of that without application. Exogenous GA significantly inhibited all parameters of mycorrhizal colonization and spore production. The spore production of GA-deficient mutant gib3 was significantly higher than that of the wild-type MM, although there was no significant difference in mycorrhizal colonization between gib3 and MM. [Conclusion] By promoting the lipid synthesis and transfer, ABA increases the colonization and arbuscular formation of AM fungi, and further enhances AM fungal sporulation.