Organic Molecules From The Suface Of Biochar Have Effects On Rice Seedling Cold Tolerance

Biochar is a carbon-rich substance produced by a dense environment,low oxygen or anaerobic conditions,and its components include carbon skeleton,inorganic nutrients and surface organic molecules.The effects of biochar on crop growth mainly include indirect and direct effects.Biochar contacts the root system of crops,which directly provides nutrients for the growth of crops,thus affecting the growth of whole crops.Biochar can increase soil fertility,improve soil,maintain water,etc.,and indirectly affect crop growth.In recent years,studies on the growth of biochar and crops have gradually increased.However,few scholars have studied which compositions of the effects for biochar on crops.The low temperature is one of the important abiotic stresses that affect the production of agronomy.In this experiment,we studied the direct effects of organic molecules on biochar surface on the crops under low temperature stress,and we adopted different concentrations of biochar eluent?0-10%by weight?.Biochar surface organic molecules can be dissolved in water,and the application of biochar solution can be used to analyze the organic molecular components to eliminate other interference.The biological carbon leaching solution was used to deal with shennong 9816 rice seedlings under low temperature stress,and the results were as follows:?1?with the increase of the concentration of biochar leacheates,the growth of rice seedlings gradually improved,including plant height,root length,dry weight and chlorophyll content,and the yellowing of leaves gradually decreased.Real-time quantitative PCR?qRT-PCR?assay cold-related genes?OsDREB1A,OsDREB1B,OsMYB2,OsWRKY76,Osi SAP8,and OsCOIN?expression of cold quantity and related physiological indexes?MDA,H₂O₂,SOD,POD,CAT,proline and soluble sugar?analysis revealed that in high concentrations of biochar leacheates?3-10%?processing,the rice seedlings increased cold resistance under the low temperature.?2?the treatment for different concentrations of biochar leacheates to rice seedlings,carries on the determination of the content of the endogenous ABA and its precursor carotenoids,the results:with biochar leacheate concentrations increases,their concentrations were increased;The expression of ABA-and cold-related genes?Os ABF1,OsABF2,Os ABA45,OsLEA3,RAB16A,OsPsbR1,and OsPsbR3?were measured,and the genes expression increased with the increase of the concentration of biochar leacheates.This test treated rice seedlings with different concentrations of exogenous ABA and determination of endogenous ABA and its precursor carotenoid contents and quantity of the related genes expression,found that the exogenous ABA test results with biochar leacheates treatment results are similar,so we guess biochar leacheates contain some components and they has the similar action to ABA.?3?We believe that in the absence of other interfering elements?inorganic nutrients such as K,Na,Ca,etc.?,the substances in biochar should be some organic molecules that can dissolve in water on the surface of biochar and protect the crops from low temperatures.We suggest that the positive influence of biochar on plant cold tolerance is because of surface organic molecules which likely function by entering a plant and interacting with stress-related proteins.Thus,to verify these mechanisms,this study used gas chromatography-mass spectrometry?GC-MS?techniques,identifying 20organic molecules in biochar extracts using the National Institute of Standards and Technology?NIST?library.?4?Further,to illustrate how these organic molecules work,we utilized the molecular docking software Autodock to show that the organic molecule 6-?Me thylthio?hexa-1,5-dien-3-ol from biochar extracts can dock with the stress-related protein zinc-dependent activator protein?ZAP1?.6-?Methylthio?hexa-1,5-dien-3-ol has a similar binding mode with the ligand succinic acid of ZAP1.It can b e inferred that the organic molecule identified in this study performs the same function as the ZAP1 ligand,stimulating ZAP1 driving cold-resistant functions,and enhancing plant cold tolerance;Similarly,we found that theorganic molec ules Cyah from biochar extract can dock with the ABA receptor protein Os P YL2,it shows the organic molecules in biochar Cyah likely to be ABA analog s and has the same function with ABA.We conclude that biochar treatment enhances cold tolerance in rice seedlings via interactions between organic molecules in the face of biochar and stress related proteins.