Phenotypic Analysis And Gene Cloning Of The Leaf Pavement Cell Mutant Pld In Arabidopsis

During the development of multicellular organisms,the differentiation and morphogenesis of various types of cells is important in developmental biology.Pavement cells in the leaf epidermis serve as an ideal model for investigating the mechanisms of cell shape formation in a multicellular system.Previously,we have identified an epidermal cell mutant named tub4^S95F95F from an EMS-mutagenized pool.To identify regulatory factors that could interact with TUB4 genetically in regulating the morphogenesis of leaf pavement cells,we remutagenized the tub4^S95F95F mutant and performed genetic screen.We obtained a mutant named 685#,which enhanced aberrant pavement cell phenotype of tub4^S95F.It showed several other defective phenotypes,including dwarf stalks,increased number of branchs,greatly reduced fertility,shorter primary roots,increased root hair length and density,shorter and thicker hypocotyls.It was then crossed to wild type and the single mutant with aberrant pavement cells was separated out in F2 population.We named the mutant pld.Compared with the wild type,the edge of pavement cells from pld mutant was smoother and the number and length of lobes were dramatically reduced.Using the molecular maker TUA6-GFP and ACT-GFP,we found that the arrangement of the microtubule and actin cytoskeleton was disturbed in pld mutant.Map-based cloning and whole genome sequencing analysis revealed a C to T substitute at nucleotide position 145 in At4g37080 and formed a TGA stop codon,resulting in a truncated protein.The T-DNA insertion lines of At4g37080 exhibited similar phenotypes to pld mutant,indicating that At4g37080 is responsible for the mutanted phenotype.Genetic analysis suggested that At4g37080 and TUB4 were independent in regulating of the leaf pavement cell morphogenesis.