| Xinjiang is the largest area and most serious of desertification in China. Thedesertization is getting worse. And vegetation restoration is accounted as the basic measuresto improve ecological environment. But restricted by the harsh natural conditions, theextreme drought-tolerant plants can survive only. Ammopiptanthus nanus is an importantleguminous shrub that has strong resistance and sand-fixation. As the tertiary relict species, itwas became the only evergreen broad-leaf species in desert in Xinjiang of China. A.nanus isconsidered to be the ideal plant of desertification control due to its characteristics ofdrought-enduring, cold resistant and prosperous root system. AM (arbuscular mycorrhizal)fungi can form symbiotic associations with the majority of terrestrial plant species. In thesymbiosis, the fungus promotes the growth of host plant, and extends the uptake of water andnutrients by roots, increases plants capability of drought and saline. Dark-septate endophyte(DSE) is a ubiquitous group of multifarious fungi that forms melanized septate hyphae andmicrosclerotia in host roots. Although there are different results in the ecological role of DSEfungi, but more and more attention has been given to its important functions in adversity.We sampled from four different sites including Kang Su, Biao Ertuokuoyi (sunny slope),Biao Ertuokuoyi (shady slope) and Shang Atushi in Xinjiang in June2012. Soil samples werecollected from the rhizosphere of A.nanus, and were divided into five depth intervals,0-10cm,10-20cm,20-30cm,30-40cm and40-50cm, respectively. The same method to collect soilsamples from Kang Su randomly from A.nanus and associated plants in both of three strains.All the samples were sieved (﹤2mm mesh size) to remove coarse roots, stones and otherlitter. Fine roots were collected from each sample for determine the spatial distribution of AMand DSE fungi. The soil samples were air-dried and stored at4°C until analysis for chemistryand fungal propagules. The main results are as follows:1. This study indicated that A.nanus formed strong symbiotic relationship with AM andDSE fungi. The total colonization of AM fungi was between72%and92.89%, and theaverage was83.2%. Average total colonization of DSE was53.22%. The formation of symbiots may be an effective strategy for A.nanus adapted to arid desert conditions.2. AM fungal colonization had significant variation in tempto-spatial distribution, thehighest total colonization appeared in the20-30cm soil depth. The total colonization of AMfungi among four sites showed the variable trend, that is, Kang Su=Shang Atushi＞BiaoErtuokuoyi (sunny slope)＞Biao Ertuokuoyi (shady slope) in this study. The colonizationin2013was significantly below in2012between the interannual.3. The total colonization of DSE had no evident trend in soil layers, but significantvariation in different sites, that is, Biao Ertuokuoyi (sunny slope)＞Biao Ertuokuoyi (shadyslope)＞Kang Su＞Shang Atushi. The colonization was significantly lower in2013thanin2012.4. The colonization of AM and DSE was closely related to soil factors. Totalcolonization of AM fungi were positive correlations with soil available P, TG (total glomalin),acid phosphatase and urease, and significant negative correlation with soil pH. There wereextreme positive correlations between hyphal colonization of DSE and soil urease, andextreme negative correlations between hyphal colonization and soil available N and pH.5. The study showed that A.nanus simultaneously infected by AM and DSE, and variousstructures appeared in the same root segment. Correlation analysis showed that almost allstructures of AM fungi were negatively related with DSE. This explains the existence ofcompetition between AM and DSE for ecological niche.6. AM and DSE colonization in A.nanus are significantly higher than those in the twocompanion plants. It is feasible to use AM and DSE to promote A.nanus revegetation anddesert environmental restoration. |
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