Preliminary Study Of The Functions Of Osarfs By Mutation

The plant hormone auxin plays an important regulatory role in the development and plastic growth of plants. One core branch underlies these effects is the hormone-mediated regulation of gene expression. A classic model for this hormone action involves interactions between trans-acting transcriptional repressor AUXIN/INDOLE-3-ACETIC ACID (IAA) proteins and transcription factor AUXIN RESPONSE FACTOR (ARF) proteins. The members of IAA proteins and ARF proteins. can interact through their conserved carboxyl-terminal domains(domainsⅢandⅣ).We obtained a semidominant mutant (Osiaa23) which showed multiple defective phenotypes and its rescued mutant designed as Osiaa23R. Through the sequence analysis, we find that Osiaa23R is a intragenic suppressor of the Osiaa23, it retains the Osiaa23 mutation and possesses an additional point mutation that affects the Tryptophan in domain IV. Therefore, we suppose that this Tryptophan in domain IV.may be essential for interactions between OsIAAs and OsARFs. We confirmed our hypothesis by the multiple alignments of the domainsIV of the rice OsIAA, OsARF proteins and by the yeast two-hybrid assays.Based on the above results, we designed a series of constructions to investigate functions of five rice OsARFs. cDNA fragment with a single Tryptophan change in domain IV of specific OsARF was inserted to the 35S promoter in vector PHB to produce a construction. The individual Pr35S::Osarf was transferred into Osiaa23 mutant via Agrobacterium tumefaciens-mediated transformation.. The transgenic plants showed increased adventitious roots than Osiaa23 mutant. The primary results suggest that these selected OsARFs may be involved in the development of rice adventitious roots.