A chimeric AtERF4 repressor modulates pleiotropic aspects of plant growth and abiotic stress tolerance in transgenic Arabidopsis

Transcription factors (TFs) fused to the SRDX (a modified repressor domain at the C-terminal region of Arabidopsis SUPERMAN (SUPRD) with the sequence of LDLDLELRLGFA) motif repression domain at their C terminus, generating a chimeric repressor, could act as a dominant suppressor and overcome problems related to functional redundancy between TFs. Here, we demonstrate that transgenic Arabidopsis containing a chimeric AtERF4-SRDX construct display a variety of changes in plant growth and development, such as short primary roots and root hairs at early developmental stages, an increased number of rosette leaves with decreased leaf area, elongation of leaf petioles and inflorescence stems, prolonged growth period, reduced stem and leaf angle and a modified seed coat mucilage structure. The short primary root and the elongation of petioles and stems were due to reduced and enhanced lengthwise cell expansion respectively, while the redistribution of seed mucilage appeared to be the result of altered pectin methylesterase activity. Expression of AtERF4-SRDX also affected abiotic stress tolerance of transgenic plants, inducing enhanced resistance to drought but reduced tolerance to salinity and heat, which could be linked to abscisic acid signaling. Altogether, our findings provide new insights into the possible functions of AtERF4 in Arabidopsis growth and development, and in mediating plant responses to abiotic stresses.