低pH影响丛枝菌根真菌丛枝发育和磷的吸收

Influences of low pH on the arbuscule development and phosphorus uptake of Rhizophagus intraradices

以番茄Solanum lycopersicum为寄主植物,在pH 3.7、pH 4.5、pH 5.5和pH 6.5条件下接种根内根孢囊霉Rhizophagus intraradices,分别在培养4周和7周取样测定低pH对丛枝菌根真菌(AMF)丛枝发育和磷吸收利用的影响。结果表明,当pH低于5.5时,低pH显著抑制AMF对根系的侵染和丛枝的形成,且抑制效应随pH的降低而增强;与侵染率相比,丛枝丰度随土壤pH的降低而降低的幅度更大;低pH显著降低了植株生物量;与不接种处理相比,接种AMF显著提高植株生物量;相关分析表明,在菌根侵染指标中丛枝丰度与植株生长相关性最高;方差分解分析表明,pH对植株生物量的贡献率(88%和77%,两次取样)大于AMF的贡献率(5%和8%,两次取样);低pH对碱性磷酸酶活性的影响与根系侵染有相似的趋势;AMF能显著提高地上部P浓度,而低pH显著降低地上部P浓度以及根系中LePT3、LePT4和LePT5的表达。这些结果表明,低pH对AMF与植物的共生关系有显著的抑制作用,其中对丛枝的形成与功能的抑制效应最大。

Tomato Solanum lycopersicum plant was inoculated with Rhizophagus intraradices at pH 3.7, pH 4.5, pH 5.5 and pH 6.5,and the influences of low pH on the arbuscule development and phosphorus uptake and utilization of arbuscular mycorrhizal fungus（AMF） was determined in four weeks and seven weeks, respectively. The results indicated that low pH significantly inhibited the AMF colonization and the arbuscular formation in roots at pH below 5.5 and the inhibitory effect was stronger with the decrease of pH. Compared with mycorrhizal colonization frequency, the arbuscular abundance decreased more greatly with the decrease of soil pH. Low pH significantly inhibited the plant biomass while inoculation with AMF significantly elevated the biomass as compared with non-inoculation treatment. Correlation analysis showed that among the parameters of mycorrhizal colonization the arbuscular abundance was the most relative to the plant growth. Variation partitioning analysis showed that the contributions to the plant biomass of pH（88% and 77%, two times of sampling） were higher than those of AMF（5% and 8%, two times of sampling）. The effect of low pH on alkaline phosphatase activity shared the similar trend to that on root colonization. AMF significantly increased the P concentration in shoot, while pH significantly inhibited the P concentration in shoots and the expression of LePT3, LePT4 and LePT5 in roots. These results suggest that low pH is significantly inhibitory to the AMF-plant symbiosis, and the inhibitory effect of low pH on the formation and function of the arbuscule was the greatest.