The Regulatory Mechanisms Of RACK1in The Roots Development Mediated By Auxin And Abscisic Acid

Plant roots absorb water and mineral nutrients,and play an essential role in the process of plant growth and development. Besides that, the growth and development of roots are closely related to plant hormones. Receptor for activated C kinase1(RACK1) induced by auxin, so it maybe play a role in the roots development. The regulatory mechanisms of RACK.1in the auxin-dependent and ABA-dependent roots development by using some mutants in Arabidopsis and rice were researched. The results were as follows.1. RACK1is a positive regulator while RGB1is a negative regulator of roots development. The regulation of AGB1in roots development is mediated by RACK1.2. RACK1, the product of gene expression induced by auxin, regulated root development by changing the level of endogenous IAA in the treatment of Exogenous1AA/T1BA. This process was negatively affected by AGB1. RACK1inhibited the expression of AtPIN1gene, but promoted the expression of AtAUX1gene. This could be one of the reasons in increased endogenous IAA levels by RACK1protein. AGB1inhibited the expression of AtPIN1gene. These two proteins worked together or Separately.3. RACK1also promoted root development in rice. IAA had bigger effect on root development with more RACK1. TIBA would make RACK1sensitive.4. RACK.1gene will add the sensitivity of lateral root primordia after adding exogenous ABA. Exogenous ABA can inhibit the occurrence of lateral root primordia and slow down the development of lateral root primordia.5. The study of ABA content in Arabidopsis roots showed that RACK1protein would reduce ABA in roots to promote the root development. AGB1also had effect in this regulation.6. Exogenous ABA treatment promoted the expression of AtPIN1and AtAUX1. In the process of AtPIN gene expression. RACK1protein and Gβ subunits have played a positive regulatory role respectively. In the process of AtAUX1gene expression, RACK1h1ad no effect on the expression of AtAUXl promoted by exogenous ABA, but regulation on the expression of AtAUX1of AGB1are regulated by RACK1.7. Low concentrations of ABA could promote root elongation and lateral roots of rice, high concentrations inhibited these two physiological processes.The primary root and lateral roots elongation pathway may be induced by the same way, and RACK1plays an important role in this way. Exogenous ABA promoted the expression of OsRACK1gene in anti690and Nipponbare, but it will inhibit the expression in ox749.Wih stimulation of exogenous IAA, RACK1protein promoted the expression of PIN1gene and AUX1gene and affected IAA levels,then promoted root development.Wih stimulation of exogenous ABA, RACK1protein promoted the expression of PIN1gene while AGB1promoted the expression of AUX1gene. IAA had effect on root development assisted by ABA.