RESUMEN
Phenylpropanoids, a class of specialized metabolites, play crucial roles in plant growth and stress adaptation and include diverse phenolic compounds such as flavonoids. Phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) are essential enzymes functioning at the entry points of general phenylpropanoid biosynthesis and flavonoid biosynthesis, respectively. In Arabidopsis, PAL and CHS are turned over through ubiquitination-dependent proteasomal degradation. Specific kelch domain-containing F-Box (KFB) proteins as components of ubiquitin E3 ligase directly interact with PAL or CHS, leading to polyubiquitinated PAL and CHS, which in turn influences phenylpropanoid and flavonoid production. Although phenylpropanoids are vital for tomato nutritional value and stress responses, the post-translational regulation of PAL and CHS in tomato remains unknown. We identified 31 putative KFB-encoding genes in the tomato genome. Our homology analysis and phylogenetic study predicted four PAL-interacting SlKFBs, while SlKFB18 was identified as the sole candidate for the CHS-interacting KFB. Consistent with their homolog function, the predicted four PAL-interacting SlKFBs function in PAL degradation. Surprisingly, SlKFB18 did not interact with tomato CHS and the overexpression or knocking out of SlKFB18 did not affect phenylpropanoid contents in tomato transgenic lines, suggesting its irreverence with flavonoid metabolism. Our study successfully discovered the post-translational regulatory machinery of PALs in tomato while highlighting the limitation of relying solely on a homology-based approach to predict interacting partners of F-box proteins.
Asunto(s)
Aciltransferasas , Proteínas F-Box , Regulación de la Expresión Génica de las Plantas , Fenilanina Amoníaco-Liasa , Filogenia , Proteínas de Plantas , Solanum lycopersicum , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Proteínas F-Box/metabolismo , Proteínas F-Box/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Fenilanina Amoníaco-Liasa/metabolismo , Fenilanina Amoníaco-Liasa/genética , Aciltransferasas/metabolismo , Aciltransferasas/genética , Flavonoides/metabolismo , Flavonoides/biosíntesis , Plantas Modificadas Genéticamente , Propanoles/metabolismoRESUMEN
The availability of automatic data analysis tools and large databases have enabled new ways of studying language and communication that were not possible in the pre-information era. Here we apply a quantitative analysis to a large dataset of USA congressional speeches made over a period of 138 years. The analysis reveals that the readability index of congressional speeches increased consistently until the 96th congress, and then started to decline. Congressional speeches have also become more positive over time, and in general express more sentiments compared to speeches made in the 19th century or early 20th century. The analysis also shows statistically significant differences between Democratic and Republican congressional speeches.