Auxin And Ethylene Regulate Arabidopsis Root Development Under Different Temperature

Our laboratory previously screened a mutant that displayed root curling phenotype when grown on the medium containing 0.1 ?M ZT,the mutant was named ckrcl-1(cytokinin induced root curling)and was identified as an auxin biosynthesis deficient mutant.The gene CKRC1 can be translated into the protein TRYPTOPHAN AMINOTRANSFERASE of ARABIDDPDIS(TAA1),the TAA1 catalyzes the tryptophan and lead to the production of indolepyruvic acid(IPA),which functions in the IPA pathway among the auxin synthesis pathways.CKRC1 is also regulated by temperature,but it is not clear whether or not temperature will affect the growth of ckrcl-1 or will regulate the auxin and ethylene signaling,therefore we performed experiments to make these questions clear.The results indicate ckrcl-1 has different root phenotype in different temperature(17?,22?,24.5,27?).When the temperature is between 22??27?,the root phenotype of ckrcl-1 is intensified and the lateral root,adventitious root increase significantly.Different isoforms of auxin have different degrees to rescue the root phenotype of ckrcl-1 grown in different temperature.The phenotype of ckrcl-1 can be completely rescued when ckrcl-1 is grown in 22? and treated with NAA and IAA.ckrcl-1 may have different sensitivity to ethylene in different temperature.Since the ckrcl-1 is insensitive to ACC,so the ckrcl-1 root is longer than wild type after the application of ACC.While,when the temperatue is 27?,ckrcl-1 and the Col-0 have the same sensitivity to ACC.Temperature and ethylene can promote auxin biosynthesis.After the temperature and ethylene treatment,the results of DR5::GUS staining indicate that the auxin level in the root tip increases significantly.The normal development of ckrcl root depends on ethylene signaling.The defects in gravitropism and the root phenotype of double mutant ckrcl/etrl-3 can not be rescued by ACC,but those phenotype of ckrcl-1 can be rescued by ACC.Therefore,ethylene regulates ckrcl-1 root development via the ethylene receptor ETR1.Auxin polar transport is important in the root development.But we don't know exactly which transporter is responsible for this procedure,so we constructed vectors to overexpression the PINl-7 and AUX1 genes.This kind of work are still going on.Our results indicate that temperature has significant effect on plant development.The interactions of auxin and ethylene,ethylene signaling itself,auxin distribution and transportation all play a vital role in the ckrcl-1 root development.We suggest that auxin and ethylene can regulate Arabidopsis root development in different temperature.