E function of auxin in responses to environmental stresses, such as drought, salinity and pathogen attack.6-8 Indole-3-acetic acid (IAA) is the major plant auxin synthesized by both tryptophan (Trp)-dependent and -independent pathways.9 Although molecular elements and physiological functions in the Trp-independent pathway are unknown, the Trp-dependent pathway is well defined as many pathways that proceed through four metabolic intermediates.5 These may be divided into the indole-3-acetaldoxime (IAOx), indole-3-acetamide (IAM), tryptamine (TAM) and indole3-pyruvic acid (IPA) pathways. Genetic and biochemical studies in Arabidopsis have shown the preponderance in the Trp-dependent pathway in de novo auxin biosynthesis. Evidently the Trp-dependent pathway is involved in embryogenesis, seedling development, flower improvement, vascular patterning, though it affects other developmental processes as well.10-13 Significantly, the IPA pathway constitutes a basic two-step pathway in Arabidopsis.14,15 The initial step is definitely the conversion of tryptophan to indole-3-pyruvic acid (IPA) by a household of tryptophan aminotransferase of Arabidopsis (TAA). The TAA family members consists of 3 closely related genes in Arabidopsis (TAA1, TAR1 and TAR2). Mutations of these genesPlant Signaling Behaviore24495-013 Landes Bioscience. Usually do not distribute.Hyeong Cheol Park, Joon-Yung Cha and Dae-Jin Yun*Figure 1. Model proposed for the function of YUCCA6 in drought strain. YUCCA6 protein is involved in auxin biosynthesis as a rate-limiting step converting IPA to IAA. Additionally, it functions in a drought stress signaling pathway by means of effects of ROS equilibrium in plants. Trp, tryptophan; TAA, tryptophan aminotransferase of Arabidopsis; IPA, indole-3-phyruvic acid; IAA, indole-3-acetic acid; ROS, reactive oxygen species.resulted in partial auxin deficiency phenotypically revealed by altered responses to shade avoidance, ethylene and auxin transport inhibitors, respectively.12,13,16 The defects of taa mutants could be partially rescued by auxin supplemented to development media.12,13 These benefits strongly suggest that the TAA loved ones genes constitute important components for auxin biosynthesis. This fact recommended detailed research on functions of TAA family members genes in crop plants. We focused Solanum tuberosum, potato, in an attempt to define and isolate putative TAA gene family members.Atogepant Depending on the potato genome database (solanaceae.Procaine plantbiology.PMID:23695992 msu. edu/pgsc_download.shtml), we isolated five putative TAA family genes, termed Solanum tuberosum TRYPTOPHAN AMINOTRANSFERASE RELATED1 to five (StTAR1 to 5). The StTARs showed around 50 deduced amino acid sequence identity with Arabidopsis TAA/ TAR1/TAR2. Also present inside the potato sequences are the characteristic alliinase C and aromatic aminotransferase domains of TAA proteins.1 In addition, the rate-limiting second step in Trp-dependent auxin biosynthesis is conversion of IPA to IAA by members from the YUCCA family of flavin monooxygenases (FMOs). Previously, the involvement of YUCCA proteins inside the TAM pathway, a unique Trp-dependent auxin biosynthesis pathway was reported due to the capability of YUCCA proteins to use TAM as a substrate.5 Thisview has been replaced by current research in Arabidopsis that revealed the function of YUCCA proteins inside the IPA pathway with TAA/TARs.14,15 In Arabidopsis, the YUCCA family consists of 11 genes. Lines overexpressing the proteins and activation-tagged mutants of individual genes showed aux.
