The Molecular Mechanism Of MiR319-TCP4 Regulating Plant Drought Response In Arabidopsis Thaliana

Drought stress leads to the decrease of water in the soil,threatens the survival rate of crops and affects the growth of crops.Therefore,drought has become the important environmental factors restricting agricultural development.ABA dependent and ABA independent pathways are signaling pathways in plant response to drought stress.It is known that ABA as a second messenger regulates the expression of downstream target genes in ABA dependent signaling pathways.However,little known about ABA independent signaling pathways,and little known about the mechanism of how plants enhance drought resistance through morphological structure and physiological metabolism.In this paper,we mainly studied the molecular mechanism of mi R319-TCP4 regulating plant drought stress.The results are following:1.Vertical cultivation of WT?jaw-D(mi R319a overexpress transgenic plant)?r TCP4-3?r TCP4-6?r TCP4-7(mi R319-resistant TCP4 overexpress transgenic plants).Through primary root length statistical analysis,the primary root length of jaw-D is longer than the wild type,while the primary root length of r TCP4-3?r TCP4-6?r TCP4-7 are shorter than the wild type.After drought treatment,the drought resistance of the r TCP4 overexpression lines is weaker than the wild type,the jaw-D is stronger than the wild type.It suggests that TCP4 may participate in drought stress response by regulating primary root elongation.The relative expression levels of RD29a,RD29b and RD22 genes in the leaves and roots of the jaw-D were higher than the wild type,while the expression levels of the r TCP4-3,r TCP4-6 and r TCP4-7 lines were lower than the wild type.2.The seed germination rate of WT?jaw-D?r TCP4-3?r TCP4-6?r TCP4-7 in1/2MS solid medium and exogenous ABA solid medium had no difference,their growth status was similar.And exogenous apply Me JA inhibited all lines's roots growth and development,exogenous apply IAA promoted all lines's roots growth and development.3.r TCP4-3×lox₂was got by crossing r TCP4-3 with the At LOX2 deletion mutant.Jaw-D×pif Q lines was got by crossing At PIF deletion mutant pif Q with jaw-D(mi R319a overexpress transgenic plant).Vertical cultivation of WT?jaw-D?r TCP4-3?lox₂?r TCP4-3×lox₂ lines,it was found that the primary root length of At LOX2 deletion mutant was the longest,while At TCP4 overexpression line r TCP4-3 was the shortest,and the F2 r TCP4-3×lox₂ line was shorter than lox₂ and longer than r TCP4-3.PEG8000 inhibited the growth of WT?jaw-D?r TCP4-3?lox₂?r TCP4-3×lox₂ lines,but there was no difference in germination rate.In the drought treatment of WT?jaw-D?r TCP4-3?lox₂?r TCP4-3×lox₂ lines,lox₂ has stronger drought resistance than r TCP4-3,and F2 line r TCP4-3×lox₂ has stronger drought resistance than r TCP4-3.In the drought treatment of WT?jaw-D?pif Q?jaw-D×pif Q lines,the jaw-D is more resistant to drought,while the pif Q is poor.The jaw-D×pif Q line and pif Q had poor drought tolerance.This result suggests that transcription factor TCP4 is involved in drought stress through jasmonic acid and auxin synthesis pathway.4.Through tobacco transient expression,EMSA and Ch IP-q PCR molecular biology experiments,it was verified that TCP4 combined with the promoter region of LOX2,PIF4 and PIF5 to active the expression of functional genes.Using biochemical and molecular biology methods to study the molecular mechanism of mi R319-TCP4 regulating plant drought stress,to study how plant hormones affect signal transduction or biosynthesis,and reveal the mechanism of plant hormone interaction.It provides the research reference on the mechanism of how plants enhance drought resistance through the interaction between morphological structure and physiological metabolism under drought conditions.