Preparation Of Plant Hormone Sensor And Determination Of IAA And SA Under Plant Salt Stress

Plant endogenous indole-3-acetic acid(IAA)and salicylic acid(SA)are naturally occurring organic compounds in plants and play an important role in plant growth and stress resistance.However,the content of endogenous hormones in plants is extremely low,and they are easily decomposed by light and heat.Therefore,it is difficult for traditional analysis methods to easily,quickly and accurately determine endogenous hormones in plants.Therefore,the research on low-cost,rapid,convenient,and high-sensitivity phytohormones has profound implications for the research of endogenous hormones.In this paper,the electrochemical sensors were used to determine the endogenous hormones in plants.The contents of endogenous IAA and SA in sunflower and soybean with different stress concentrations(0,50,100 mM NaCl)and different stress time(0,12,24,36 h)were determined.The results are compared with traditional methods of measurement.This study also ground-breakingly developed a real-time in vivo phytohormone measurement sensor to achieve real-time in vivo determination of plants.Research indicates:(1)Preparation and application of indole acetic acid immunosen-sors.The double amplification of the detection signal was based on the formation of PAMAM and AuNPs(anti-IAA)antibodies,and the phy-tohormone was first determined by electrochemical impedance spec-troscopy(EIS).The results showed that the immunosensor has a wide range of detection:10 pg/mL-10 ?g/mL,LOD=4.62 pg/mL(S/N=3).The endogenous hormones of sunflower under different concentrations of salt were detected in vitro by incubating plant homogenate.The IAA content of sunflower measured by the sensor decreased with the in-crease of salt stress concentration,and was compared with ultra-high performance liquid chromatography-mass spectrometry.The results were similar and the trends were consistent.(2)Preparation and application of indole acetic acid in vivo de-tection sensors.A stainless steel electrode(d = 0.25 mm)was used as a detection electrode to etch the surface into a nanopore structure.After electrodeposition of gold nano-and platinum nano-graphene compo-sites,the specific surface area of the electrode was increased,and fi-nally the sensor was made by modifying the eosin T(PST).The ex-perimental results showed that the detection range of the electrode was 100 pg/mL-100 ?g/mL and the detection limit was 43 pg/mL(S/N=3).Sensors were used to measure the in-situ of oil soybeans under salt stress directly inserted into seedling stems.Differential pulse voltam-metry(DPV)can clearly show the peak value of IAA at 7.0 V.The rsults show that at different times(12,24,36 h))Under 100 mM salt stress,the endogenous IAA of soybean first showed a significant in-crease in stress response and then decreased sharply with increasing stress time.And the sensor measurement results and UPLC-MS results tend to be consistent.(3)Preparation and application of salicylic acid in vivo detection sensors.Based on Pt nanoflower/ERGO one-step electrodeposition on platinum microfilament electrode.After deposition,the microelectrode showed high sensitivity and selectivity for SA,ie the detection range was 100 pM-1 ?M and the detection limit was 48.11 pg/mL(S/N=3).The SA content in stems of sunflower seedlings under different salt stress was measured in vivo using a miniature sensor.The results showed that the content of endogenous salicylic acid in plants showed a decreasing trend with the increase of the stress concentration,and the results were verified by gene expression analysis and UPLC-MS for the qualitative and quantitative verification.The sensor prepared in this study has a lower detection limit and a wider linear range than the traditional measurement method.It can detect trace samples,and the measurement results are in good agrement with UPLC-MS after excluding signal-to-noise ratio interference.The results of determination of phytohormones under salt stress indicated that soybean IAA had stress effects at the initial stage under different stress conditions of 100 mM,and the IAA content of the soybean IAA increased transiently,and then decreased rapidly with the increase of salt stress.Under different salt stress conditions,the endogenous IAA content of sunflower increased with the increase of salt stress concen-tration.The endogenous SA of sunflower also showed a downward trend,and the downward trend increased with the increase of salt stress concentration.