| Arbuscular mycorrhizal fungi (AM) can form reciprocal symbiosis withmore than80%of the terrestrial vascular plants. As important soilmicroorganism, AM fungi completes its life cycle using photosynthetic carbonfrom host plants, meanwhile, AM fungi can improve the mineral nutritionabsorption of host plants, facilitate the growth and development of host plants,and increase the adversity resistance of host plants. This mutualist relationshipsbetween AMF and host plants has important significance to maintain ecologicalbalance and agricultural sustainable development. Recently, under globalclimate change, adverse climates frequently occurred. Chilling has seriouslyimpact on crop production and one of the reason for inducing the decrease ofmaize production. This study uses maize as study object which is primary graincrop in northeast China, based on pot experiment, firstly we screened the AMfungi species which was advantage for growth of maize under low temperature,then we systematically study the physiological mechanism for AM fungiimproving the low temperature resistance of maize with respect to thephysiogenesis, carbon and nitrogen metabolism, and mineral nutritionabsorption. We aimed to reveal the potential effects of AM fungi on lowtemperature resistance of host plants, and provide reference for developingbiological fertilizer and promoting agricultural sustainable development. Asfollowed are main study results: We used G. etunicatum, G. tortuosum, A. scrobiculata and G. intraradicesas experimental AM fungi species, and conducted a pot experiment of maizeunder ambient and low temperature. We compared the effects of four AM fungispecies on improving low temperature resistance of maize with regard of themycorrhizal development, pant growth, osmotic adjustment and antioxidantenzyme. The results indicated that low temperature significantly influenced thecolonization of different AM fungi on root of maize seedlings, and decreased theplant height, total dry weight, increased underground dry weight and shoot/root,and changed the praline and malonaldehyde (MDA) content of maize seedlings,and influenced the antioxidant enzyme activity; AMF inoculation changedshoot/root of maize seedlings, and increased the praline content of maizeseedling, and decreased the MDA content of maize seedlings, and increased thesuperoxide dismutase (SOD), catalase (CAT) and Peroxidase (POD) activity. Ingeneral, AM fungi inoculation enhanced the low temperature resistance of maizeseedling, but differentAM fungi species had different effects on low temperatureresistance of maize. Comprehensive comparison, G. tortuosum had morepotential to improve low temperature resistance of maize seedling.Using the G. tortuosum, we studied the carbon metabolism under lowtemperature stress by pot experiment indoor. Study results indicated that lowtemperature stress significantly decreased the colonization of maize root, rootlength, root area, root volume and root dry weight, and decreased thechlorophyll and carotenoid content of maize leaf, chlorophyll a/b, net photosynthetic rate (Pn), Stomatal conductance (Gs), transpiration rate (Tr),Maximal fluorescence (Fm), variable fluorescence (Fv), Maximum quantumefficiency (Fv/Fm) and Potential photochemical efficiency (Fv/Fo); lowtemperature increased the sucrose synthetase SS and Sucrose phosphatesynthase SPS activity of maize leaf, and increased the soluble sugar andreducing sugar content of maize leaf. Under ambient temperature, AM fungiinoculation decreased plant height, leaf length and width, and leaf area index;under low temperature, AM fungi inoculation could increase plant height, leaflength and width, and shoot/root. AM fungi inoculation significantly increasedthe Pn, Gs and Tr of maize leaf, and alleviated the influence of low temperatureon photosynthetic of maize. Meanwhile, AM inoculation increased the SPSactivity and decreased the SS activity, and increased the reducing sugar andsucrose content, which suggested that AM inoculation could effectively alleviatethe damage of low temperature on photosynthetic of maize, increase solublematter content, and change the carbon metabolism enzyme activity, and increasethe accumulation of nonstructural carbohydrates, consequently to increase theadaptation of maize to low temperature by improve carbon metabolism capacityof maize.Low temperature reduced the total nitrogen, nitrate nitrogen, ammoniumnitrogen, protein and amino acid content, but increased the nitrate reductase,glutamine synthetase, glutamine synthetase and cereal third transaminase enzyme activity. AM inoculation increased the total nitrogen, nitrate nitrogen,soluble protein and amino acid content. Under ambient temperature, AMinoculation increased the ammonium nitrogen content of maize leaf, while underlow temperature, AM inoculation decreased the ammonium nitrogen content ofmaize leaf. AM inoculation likewise increased the nitrate reductase, glutaminesynthetase, glutamine synthetase and cereal third transaminase enzyme activity,and effect the nitrogen metabolism process, and further influenced the lowtemperature resistance of maize. The relationship between carbon metabolismand nitrogen metabolism of maize seedlings with AM fungus indicated that AMreduced the carbon consummation of response matter under low temperaturestress. The regulation of relationship between carbon metabolism and nitrogenmetabolism of maize may be an effective mechanism forAM to improve the lowtemperature resistivity.Similarly, AM impacted the mineral nutrition absorption of maize seedlingunder low temperature stress. Low temperature decreased the shoot and rootphosphorus (P) content, and decreased the shoot potassium (K), calcium (Ca),magnesium (Mg), sulphur (S), manganese (Mn)，copper (Cu) and zinc (Zn)content. Not only low temperature decreased shoot sodium (Na), manganese(Mn), iron (Fe), copper (Cu) and zinc (Zn) absorption, but also decreased rootCu and Zn absorption of maize. AM inoculation increased the shoot K contentand (Cu) and zinc (Zn) absorption under low temperature; AM inoculationincreased the root P and Zn content, and decreased root Al content. Under ambient temperature, AM inoculation impacted root Na, Fe, Cu and Znabsorption of maize root. The interaction between temperature and AMFsignificantly impacted the Al content and absorption of maize root. These resultsindicated that AM had important effects on mineral nutrition absorption of maizeseedling under low temperature stress. Therefore, with respect to nutrient supply,AM fungus can enhance the mineral nutrition absorption of host maize, furtherto increase photosynthetic characteristics, which is advantage for maize growthand resistance to low temperature stress. |
PDF Full Text Request