丛枝菌根真菌侵染指标与植物促生效应相关性分析

Correlation analysis between arbuscular mycorrhizal fungi colonization indices and plant growth promoting effect

关键词:  丛枝菌根真菌  玉米  紫花苜蓿  侵染率  根外菌丝密度  磷吸收量

Key words:  arbuscular mycorrhizal fungi  Zea mays L.  Medicago sativa L.  colonization rate  hyphal length density  phosphorus uptake

摘要:

为探讨不同丛枝菌根真菌(Arbuscular mycorrhizal fungi，AMF)生长特性与功能(植物生长和养分吸收)的相关性。采用分室根箱装置，以玉米(Zea mays L.)和紫花苜蓿(Medicago sativa L.)为宿主植物，选取7种AMF:摩西斗管囊霉Funneliformis mosseae、变形球囊霉Glomus versiforme、根内根孢囊霉Rhizophagus intraradices、幼套近明球囊霉Claroideoglomus etunicatum、近明球囊霉C. claroideum、细凹无梗囊霉Acaulospora scrobiculata、黏屑多样孢囊霉Diversispora spurca，以不接种为对照进行温室盆栽试验，测定菌根侵染率、根外菌丝密度、植物地上部生物量、磷/锌吸收量、植物根系AMF gDNA丰度以及玉米根系ZmPht1；6的相对表达量。结果表明:接种F.mosseae、R.intraradices、G.versiforme、C.etunicatum的玉米和紫花苜蓿根系侵染率及根外菌丝密度较高，对植株生长和磷、锌吸收均表现为正效应；C.claroideum、A.scrobiculata、D.spurca根系侵染率和根外菌丝密度较低，C.claroideum对紫花苜蓿生长和磷吸收表现为促进效应，而对玉米表现出抑制效应，后两者对植株生长和磷、锌吸收无显著效应或抑制作用；AMF的生长指标(菌根侵染率和根外菌丝密度)与菌根生长效应以及磷、锌吸收效应之间均具有较高的正相关性，根系AMF总侵染率对玉米菌根生长效应、磷/锌吸收效应变异的解释量分别为79.0%，77.6%和74.1%；菌丝侵染率对紫花苜蓿菌根生长效应、磷/锌吸收效应变异的解释量分别为76.5%，72.6%和74.0%；此外，仅紫花苜蓿根系AMF gDNA丰度与根系总侵染率显著正相关，玉米根系ZmPht1；6基因的相对表达量与菌根磷吸收效应显著正相关。综上，AMF的侵染指标显著影响植物生长和养分吸收效应，AMF gDNA丰度可作为表示AMF生长的指标，但因植物而异，玉米根系ZmPht1；6的相对表达量在一定程度上可反映AMF吸磷能力。

Abstract:

To explore the correlation between the growth characteristics and functions(plant growth and nutrient absorption)of arbuscular mycorrhizal fungi(AMF), a two-compartment pot experiment containing seven different AMF species: Funneliformis mosseae, Glomus versiforme, Rhizophagus intraradices, Claroideoglomus etunicatum, Claroideoglomus claroideum, Acaulospora scrobiculata, Diversispora spurca and non-inoculated control(CK), were designed for tests with maize(Zea mays L. )and alfalfa(Medicago sativa L. )as host plants. The mycorrhizal colonization rates, hyphal length densities, shoot biomass, shoot P/Zn uptake, AMF gDNA abundance in plant roots and the relative expression of ZmPht1; 6 gene in maize roots were determined. The results showed that: F. mosseae, R. intraradices, G. versiforme and C. etunicatum had higher colonization rates in the roots and hyphal length densities in the rhizosphere of maize and alfalfa, and displayed a positive response on the plant growth, plant P and Zn uptake. C. claroideum, A. scrobiculata and D. spurca had lower colonization rates and hyphal length densities. C. claroideum had a promoting effect on growth and P uptake of alfalfa, but had an inhibitory effect on the growth, P and Zn uptake of maize. The latter two had no significant effect or even inhibitory effect on the plant growth, plant P and Zn uptake. Highly positive correlations were found between AMF growth indices(total colonization rate and hyphal length density)and the mycorrhizal growth response and mycorrhizal P and Zn uptake response. Total colonization rate of maize contributed 79. 0% variations of mycorrhizal biomass response, 77. 6% of mycorrhizal phosphorus uptake response and 74. 1% of mycorrhizal zinc uptake response, respectively. The hyphal colonization rate of AMF in alfalfa roots contributed 76. 5% variation of mycorrhizal biomass response, 72. 6% of mycorrhizal phosphorus uptake response and 74. 0% variation of mycorrhizal zinc uptake response. In addition, a significant positive correlation was found between AMF gDNA abundance and total colonization rate of alfalfa roots. There was also a significant positive correlation between the relative expression of ZmPht1; 6 genes and mycorrhizal phosphorus uptake response in maize. In conclusion, the infection indices of AMF are the main factors affecting mycorrhizal growth and the nutrient uptake response of host plants. AMF gDNA abundance can be used as an indicator of AMF growth, but it varies with plants. To a certain extent, the relative expression of ZmPht1; 6 of maize roots can reflect the P absorption function of AMF.