Solanum lycopersicum agamous-like MADS-box protein AGL15-like gene, SlMBP11, confers salt stress tolerance

Abstract

MADS-box family transcription factors are key regulators of plants and are involved in many biological processes. However, to date little information regarding stress-related MADS-box genes is available in tomato. To further elucidate the function of the SlMBP11 gene in response to abiotic stress, we generated transgenic tomato plants with knockdown SlMBP11 by RNA interference (RNAi) and plants overexpressing SlMBP11, and investigated the effects of salt stress on wild-type (WT), RNAi and overexpressing plants. In our study, seedling growth of SlMBP11-RNAi plants was more inhibited by salt than that of WT at post-germination stage, and RNAi plants became less tolerant to salt stress than WT plants in soil, which was demonstrated by lower relative water and chlorophyll content, and higher relative electrolyte leakage and malondialdehyde (MDA) content. In contrast, overexpressing plants had no obvious difference from WT seedlings when challenged by NaCl at post-germination stage, and overexpression of SlMBP11 in tomato enhanced tolerance to salt stress, which was confirmed by lower relative electrolyte leakage and MDA content, and higher water and chlorophyll content in transgenic plants. In addition, the expression of genes related to chlorophyll biosynthesis, photosystem and stress was changed in opposite directions in SlMBP11-RNAi and overexpressing plants under control and salt-stressed conditions. Together, these results highlighted the important role of SlMBP11 as a stress-responsive transcription factor in the positive modulation of salt-stress tolerance, possibly through an abscisic acid-independent signaling network, and may have promising applications in the engineering of salt-tolerant tomato.