Functional Analysis Of OsMYB48-1 Transcription Factor

Transcription factors play a regulatory role in plant growth,development and physiological and biochemical responses by participating in the regulation of the expression of target genes in eukaryotes.There are many families of transcription factors related to rice growth and development,among which MYB transcription factor is one of the most common family.According to the repeated number of highly conserved MYB domains composed of 51 or 52 amino acid residues at the N terminal,MYB transcription factors are divided into four subclasses consisting of 1R-MYB,R2R3-MYB,3R-MYB,and 4R-MYB.Among them,R2R3-MYB is the largest group being investigated.The objective of this study was to identify the function of OsMYB48-1 by using transgenic rice up-regulating OsMYB48-1 expression and editing OsMYB48-1 with CRISPR-Cas9.The main results are as follows:OsMYB48 has two kinds of variable shear modes,OsMYB48-1 and OsMYB48-2.The complete ORF of OsMYB48-1 is 633 bp,encoding 210 amino acids.It has two conserved MYB domains,belonging to the R2R3-MYB transcription factor family.Sequence analysis of OsMYB48-1 showed that it is an unstable hydrophilic protein and most similar to AtMYB59.The experiment of yeast self-activation showed that OsMYB48-1 has transcriptional activation activity.Subcellular localization result indicated that OsMYB48-1 is located in the nucleus.The expression pattern of OsMYB48-1 was analyzed by real-time quantitative PCR.The highest transcript level of OsMYB48-1 was observed in the roots.OsMYB48-1 transcript was induced by dehydration,salt and ABA treatment,but reduced by chilling stress.Transgenic rice plants overexpressing OsMYB48-1 or editing OsMYB48-1 by CRISPR-Cas9 were generated,and their phenotypes and abiotic stress tolerance were analyzed.Compared to the wild type,higher levels of root elongation during seed germination stage,seed setting rate and weight of 1000 grains were observed in homozygous lines of transgenic rice overexpressing OsMYB48-1,with higher lignin content in mature leaves.In addition,transgenic rice plants had elevated tolerance to osmotic stress and salt.No obvious phenotype was observed in the rice plants with editing OsMYB48-1 as compared with the wild type.The results indicated that OsMYB48-1 is involved in regulation of growth and development as well as abiotic stress tolerance in rice.