Adaptability Of The Colonization Of Two Types Of Mycorrhizal Fungi In Roots Of Artemisia To The Environment At A Regional Scale

Mycorrhiza is one of the most important root traits affecting plant growth and survival.Mycorrhizal fungi can not only increase the absorption of water and nutrients and maintain plant growth,but also enhance the resistance of host plants to stressful environments.However,the geographical patterns of mycorrhizal fungi and their roles in the adaptation of host plants to environmental gradients at the regional scale are still unclear.In order to determine the geographical patterns of colonization of mycorrhizal fungi and their reponses to environmental factors(temperature,precipitation and soil),we selected a transect in eastern and central China,which spanned over 15 provinces,municipalities and autonomous regions.We collected 1023 Artemisia plants from 81 sites along the transect.We measured the colonization of arbuscular mycorrhizal fungi(AMF)and dark has separated endophytic fungi(DSE)in roots by the staining method and used general linear mixed models to determine the relationship between mycorrhizal colonization and environmental gradients.The results were as following:(1)Both AMF and DSE were present in the roots of Artemisia.The colonization of AMF(colonization rate and density was 61.6% and 4.03%,respectively)was higher than that of DSE(colonization rate and density was 21.25% and 1.88%,respectively).There was no significant correlation in colonization between the two types of mycorrhizal fungi.(2)Colonization rate and density of AMF and DSE were not significantly different among Artemisia species,indicating that the two types of mycorrhizal fungi had no host specificity.(3)Colonization rate and density of AMF and DSE had no significant latitudinal pattern.Colonization density of AMF and colonization rate,density of DSE had no significant longitudinal pattern.However,colonization rate of AMF showed longitudinal pattern,namely AMF colonization rate increased with the increase of longitude.(4)AMF colonization rate was significantly and positively correlated with the first axis of principal component analysis on climatic factors(constructed by mean temperature in the driest season,mean temperature in the coldest season,lowest temperature in the coldest month,average annual temperature,mean monthly temperature,average annual precipitation,precipitation in the driest season and precipitation in the coldest season).Colonization rate or density of AMF and DSE was neither correlated with the second principal component of climate or the first two axises of soil factors.These results showed that the mycorrhizal fungi(AMF and DSE)were widely presented in the roots of Artemisia plants at the regional scale.There was no correlation between the colonization degree of the two types of mycorrhizal fungi,indicating that they have independent way of colonization.The two types of mycorrhizal fungi had no host specificity.AMF colonization rate showed significant longitudinal pattern,which was driven by its responses to regional temperature and precipitation gradients.Our results not only reveal that the presence of mycorrhizal fungi enhances the adaptability of host plants to the regional environment,but also points out that the different responses between AMF and DSE in response to climate and soil gradients should be distinguished when predicting the response of mycorrhiza to the environmental change.Our results suggested the adaptation of plants to large-scale environmental gradients was enhanced by adjusting mycorrhiza colonization,and provide a theoretical support for understanding the relationship between the two types of mycorrhiza and predicting responses of plants to future climate change.