Identiifcation And Function Analysis Of The Gene LAZY1that Involved In Gravitropic Growth Of Maize

The negative gravitropic growth habit of plant, which have important roles atmanipulating plant’s gesture, alleviating the damages caused by severe weather and improvingyields, is a very intricate process. Although researchers have made so many exciting advances,there are still lots of details have not been explained properly. The mazie mutant lazy1wasfirst discovered in1936, whose negative gravitropic growth habit were partially disappearedat the coleoptiles period and totally disappeared when it growth into maturity. Compared withthe wild type, the lazy1have disordered distribution of auxin in coleoptiles, but normallyfunctioning amyloplasts, which indicated that LAZY1may have an indispensable function inthis signal transduction. The deeper scientific research of LAZY1shoule have a theoreticaland practical significance.Through homology analysis, we found that two allelicmutant, lazy1-1and lazy1-2, bothhave some nucleotides losted at the locus LOC100276689, where a gene is homologous toOsLAZY1. Bioinformatics prediction showed that, LAZY1have a membrane location signalat the N terminal, but not any nucleus location signal at the C ternimal as OsLAZY1.Subcellular localization analysis indicated that LAZY1was located in the cell membrane andthe nucleus. The yeast two-hybrid results showed that, LAZY1could interact with membersof AUX/IAA family. These proteins in AUX/IAAs family, which can bind with transcriptionalactivator ARFs to form a heterodimer, are involved in the regulation of the expression of geneassociated with auxin. The auxin receptor, ubiquitin ligase enzyme SCFTIR1, can be activitedby auxin and lead to the degradation of AUX/IAAs, with releasing the ARFs to initiate geneexpression. Deficits of LAZY1might affect plant gravity reaction process through perturbingthe transcription regulations of some genes. In addition, LAZY1could also interact withprotein kinase C like proteins and calcyclin binding protein. Protein kinase C plays animportant role in the pHospHoinositide signaling pathway, whose activation requires Ca²⁺andmembrane lipid DAG. When DAG appears at the plasma membrane, the cytosol proteinkinase C will be incorporated into the plasma membrane, and then be activated with theappearance of Ca²⁺. Calcyclin binding protein is also related to Ca²⁺, which may be involved in Ca²⁺dependent ubiquitination pathway. Previous Studies showed that pHospHoinositidesignaling pathway play an important role in plant tropic growth and that the auxin effluxprotein PIN1’s subcellular localization is affected by intracellular Ca²⁺concentration. LAZY1might regulate the expression of certain genes or the subcellular localization of some auxintransport carrier via pHospHatidylinositol signal pathway, to control the plant gravity reactionprocess.