The Mechanism Of Arbuscular Mycorrhizal Fungi And Potassium Regulating Salt Tolerance And Potassium Absorption Of Lycium Barbarum

An potting experiment was conducted to explore the effect of inoculating with AMF?Rhizophagus intraradices?and adding potassium?K?on growth status,water and nutrient absorption,photosynthesis,anti-oxidation capcity and osmotic regulation of Lycium barbarum L.under salt stress.TAIL-PCR technology was used to obtain the Lb HAK promoter,Lb HAK promoter was inserted into tobacco through Agrobacterium-mediated method,afterculturing and testing the transgenic tobacco that containing Lb HAK promoter was obtained finally.The main findings are as follows:1. AMF improved the total root length,root surface area,root volume and biomass of L.barbarum,because AMF and L.barbarum root formed a good symbiotic relationship.Salt stress increased hyphal colonization rate and total colonization rate,decreased spore colonization rate.AMF colonization was related to K,the arbuscular colonization rate was increased with the increase of K concentration.K increased root growth of L.barbarum by increasing arbuscular colonization rate,and increased the dry weight of inoculated plants.It showed that both AMF and K can promote the growth of L.barbarum and had a synergistic effect.2. Salt stress reduced Tr and RWC and proline; soluble protein,Tr and RWC of inoculated plants increased under salt stress of L.barbarum seedlings;K increased the RWC,Tr of inoculated plants and i WUE of non-inoculated plants.The results indicated that AMF and K can enhance water absorption of L.barbarum seedlings under salt stress;AMF could maintain osmotic balance by accumulating proline and soluble protein,and K can replace proline for osmotic regulation to some extent.3. Salt stress reduced root P,Ca,Mg,K/Na,Lb SKOR of L. barbarum roots,Na and significantly increased shoot/root Na;AMF reduced Na and shoot/root Na and increased K and P content,K/Na,Lb KT1,Lb SKOR,Lb KAT3,Lb HAK;K,K/Na,Lb KT1,Lb KAT3,Lb HAK increased significantly with the increase of K concentration;and adding K also increased N and Ca in different parts of plants under salt stress to different degrees.It showed that AMF reduced the accumulation of Na in the above ground of plants under salt stress.Both K and AMF could promote nutrient absorption of L.barbarum under salt stress,and increase K and K/Na by up-regulating K absorption related genes to maintain ion homeostasis.4. The co Salt stress increased the content of H₂O₂ and O₂^-on the above ground of L.barbarum;AMF reduced above ground MDA content of L.barbarum,and increased POD and CAT in different parts of the plant in different levels;high concentration of K treatment reduced the ROS of non-inoculated plants.The above-ground SOD,POD and APX activities of inoculated plants increased with the increase of K concentration under salt stress.The results indicated that AMF and K could enhance the antioxidant capacity of L.barbarum under salt stress by removing ROS and increasing the activity of some antioxidant enzymes.AMF increased Pn,Gs,Fv/Fm,?PSII and q P of L.barbarum under salt stress;as the concentration of K treatment increased,the Pn and?PSII of L.barbarum increasedunder salt stress.6. TAIL-PCR technology was used to clone the Lb HAK promoter.Through analysis and prediction,the results showed that Lb HAK promoter contained multiple promoter core elements,elements related to light regulation as well as the elements which were related to nodulation and AM symbiosis.The linearized vector was obtained by double digestion,and the inserts with identical homologous sequences corresponding to the two ends of the linearized cloning vector p BI121 at the 5'and 3'ends were amplified.A one-step cloning kit was connected and sequenced,and the positive plasmid Agrobacterium was used for heat shock transformation to obtain Agrobacterium containing the Lb HAK promoter expression vector.7. Five sets of differentiation media with different hormone ratios and six sets of rooting media with different compositions were designed to optimize the regeneration system of tobacco plants with the same genetic background.The results showed that the ratio of NAA:6-BA was 1:15,MS medium containing 0.1 mg/L NAA and 1.5 mg/L 6-BA was the most suitable for tobacco leaf differentiation culture,and MS medium containing 0.1 mg/L NAA was the most suitable for induction root.The tolerance of explants Kan concentration and the factors affecting genetic transformation were selected.The results showed that when the explants had an OD₆₀₀ of 0.1 and the infection time was 5 min,the leaves germinated more and the differentiation effect was the best.Then they were selected and cultured on differentiation medium containing 100 mg/L Kan and 250 mg/L Cb,and finally transferred to rooting medium containing the same resistance to induce rooting,transplanted and tested to obtain positive transgenic plants.