Fornalé Silvia, Lopez Eric, Salazar-Henao Jorge E, Fernández-Nohales Pedro, Rigau Joan, Caparros-Ruiz David
Centre for Research in Agricultural Genomics (CRAG), Consorci CSIC-IRTA-UAB-UB Edifici CRAG Campus de Bellaterra de la UAB, 08193 Cerdanyola del Valles, Barcelona, Spain.
Plant Cell Physiol. 2014 Mar;55(3):507-16. doi: 10.1093/pcp/pct187. Epub 2013 Dec 5.
The phenylpropanoid metabolic pathway provides a wide variety of essential compounds for plants. Together with sinapate esters, in Brassicaceae species, flavonoids play an important role in protecting plants against UV irradiation. In this work we have characterized Arabidopsis thaliana AtMYB7, the closest homolog of AtMYB4 and AtMYB32, described as repressors of different branches of phenylpropanoid metabolism. The characterization of atmyb7 plants revealed an induction of several genes involved in flavonol biosynthesis and an increased amount of these compounds. In addition, AtMYB7 gene expression is repressed by AtMYB4. As a consequence, the atmyb4 mutant plants present a reduction of flavonol contents, indicating once more that AtMYB7 represses flavonol biosynthesis. Our results also show that AtMYB7 gene expression is induced by salt stress. Induction assays indicated that AtMYB7 represses several genes of the flavonoid pathway, DFR and UGT being early targets of this transcription factor. The results obtained indicate that AtMYB7 is a repressor of flavonol biosynthesis and also led us to propose AtMYB4 and AtMYB7 as part of the regulatory mechanism controlling the balance of the main A. thaliana UV-sunscreens.
苯丙烷代谢途径为植物提供了各种各样的必需化合物。在十字花科植物中，类黄酮与芥子酸酯一起，在保护植物免受紫外线辐射方面发挥着重要作用。在这项工作中，我们对拟南芥AtMYB7进行了表征，它是AtMYB4和AtMYB32的最接近同源物，被描述为苯丙烷代谢不同分支的阻遏物。对atmyb7植物的表征揭示了几个参与黄酮醇生物合成的基因的诱导以及这些化合物含量的增加。此外，AtMYB7基因表达受到AtMYB4的抑制。因此，atmyb4突变体植物的黄酮醇含量降低，再次表明AtMYB7抑制黄酮醇生物合成。我们的结果还表明，AtMYB7基因表达受盐胁迫诱导。诱导试验表明，AtMYB7抑制类黄酮途径的几个基因，DFR和UGT是该转录因子的早期靶标。获得的结果表明，AtMYB7是黄酮醇生物合成的阻遏物，这也使我们提出AtMYB4和AtMYB7是控制拟南芥主要紫外线防护剂平衡的调控机制的一部分。
