Study On The Regulation Mechanism Of Aspergillus Aculeatus In Response To Salt Of Bermudagrass

There is 550 million mu of saline-alkali land resources in China,among which the severe saline-alkali land accounts for about 6%.Saline-alkali land directly affects the phenotypic morphology,growth and physiological characteristics of plants,which severely limits the growth of plants.Therefore,the study of salt-tolerance mechanism of plants and the adjustment mechanism of plants to salt stress has great significance for the selection and breeding of new salt-tolerant varieties.Under the condition of severe salinized soil and shortage of water resources,the remediation measures of excessive consumption of water resources will change dramatically.Among the many saline-alkali land improvement measures,microbial improvement measures,a new saline-alkali land improvement technology,has gradually become a research hotspot globally.Aspergillus aculeatus not only has the functions of secreting auxin,iron carrier,dissolving phosphorus and potassium,but also showed great salt tolerance.Therefore,physiological characteristics of 17 bermudagrass(Cynodon dactylon)samples were studied under salt stress.Then,two kinds of bermudagrass which are extreme salt tolerance and salt sensitive separately were used to explore the regulatory effect of A.aculeatus under salt stress,and the growth and physiological mechanism of its regulation on the salt tolerance.The main research results are as follows:1.Comprehensive evaluation of salt tolerance of bermudagrass."WBD128" and "WBD145" were identified as extremely salt-tolerant and extremely salt-sensitive strains separately in 17 high seed setting rate bermudagrass strains by measuring the lawn quality,evapotranspiration,chlorophyll and other phenotypes and physiological indexes,combining the fuzzy mathematics method of subordinate function values analysis."WBD13" and "WBD177" were identified as relatively salt-tolerant strains,and "WBD90" was the relatively salt-sensitive strains.2.Salt tolerance verification of bermudagrassThe salt tolerance of "WBD128","WBD13","WBD177","WBD90" and "WBD145" strains screened in the first step were verified.Growth and physiological indexes such as lawn mass,evapotranspiration,chlorophyll and carotenoid contents,dead leaf rate,relative water content,relative electrical conductivity,osmotic regulator and ion content were measured.At 2% salt concentration,the growth parameters and physiological indexes of salt-tolerant bermudagrass were significantly better than that of salt-sensitive bermudagrass,and "WBD128" and "WBD145" were the most salt-tolerant and salt-sensitive strains in the bermudagrass respectively.3.Mechanism analysis on the salt tolerance ability of bermudagrass regulated by A.aculeatus.Under salt stress,two kinds of bermudagrass materials,"WBD128"(extremely salt tolerant)and "WBD145"(extremely salt sensitive),were used to explore the salt tolerance regulation mechanism of A.aculeatus on "WBD128" and "WBD145".The salt tolerance regulation mechanism was revealed mainly through growth and physiological means.The test results were as follows:Exogenous applied A.aculeatus fungus could significantly improve growth rate,turf quality,total chlorophyll and carotenoid content,K+ content,reduce the relative conductivity,the content of proline,H2O2 content,content of Na+,Na+/Ca2+,Na+/K+ ratio of "WBD128" and "WBD145" under salt stress.The above results show that,exogenous applied A.aculeatus fungus under salt stress could enhance the growth status of bermudagrass,photosynthesis,osmotic regulation and membrane steady-state,reduce the oxidative damage of ROS,effectively improve the growth of the state.Moreover,the growth promoting effect of "WBD145" was stronger than that of "WBD128".Based on the above results,it could be concluded that under salt stress,the salt tolerance regulation mechanism of A.aculeatus on "WBD128" and "WBD145" was not the same.However,both of them promoted its growth and development,and had a stronger growth-promoting effect on "WBD145",and preliminarily revealed the salt tolerance regulation mechanism of extremely salt tolerant and extremely salt sensitive germplasm,which laid a foundation for breeding salt-tolerant strains with high seed setting rate and for cross breeding.