ABSTRACT
In Arabidopsis thaliana, LESION SIMULATING DISEASE 1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) and PHYTOALEXIN DEFICIENT 4 (PAD4) proteins are regulators of cell death (CD) in response to abiotic and biotic stresses. Hormones, such as salicylic acid (SA), and reactive oxygen species, such as hydrogen peroxide (H2 O2 ), are key signaling molecules involved in plant CD. The proposed mathematical models presented in this study suggest that LSD1, EDS1 and PAD4 together with SA and H2 O2 are involved in the control of plant water use efficiency (WUE), vegetative growth and generative development. The analysis of Arabidopsis wild-type and single mutants lsd1, eds1, and pad4, as well as double mutants eds1/lsd1 and pad4/lsd1, demonstrated the strong conditional correlation between SA/H2 O2 and WUE that is dependent on LSD1, EDS1 and PAD4 proteins. Moreover, we found a strong correlation between the SA/H2 O2 homeostasis of 4-week-old Arabidopsis leaves and a total seed yield of 9-week-old plants. Altogether, our results prove that SA and H2 O2 are conditionally regulated by LSD1/EDS/PAD4 to govern WUE, biomass accumulation and seed yield. Conditional correlation and the proposed models presented in this study can be used as the starting points in the creation of a plant breeding algorithm that would allow to estimate the seed yield at the initial stage of plant growth, based on WUE, SA and H2 O2 content.
Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Carboxylic Ester Hydrolases/metabolism , DNA-Binding Proteins/metabolism , Hydrogen Peroxide/metabolism , Salicylic Acid/metabolism , Seeds/growth & development , Transcription Factors/metabolism , Water/metabolism , Acclimatization/radiation effects , Arabidopsis/growth & development , Models, Biological , Mutation/genetics , Photosynthesis/radiation effects , Stress, Physiological/radiation effects , Ultraviolet RaysABSTRACT
KEY MESSAGE: Arabidopsis and poplar with modified PAD4, LSD1 and EDS1 genes exhibit successful growth under drought stress. The acclimatory strategies depend on cell division/cell death control and altered cell wall composition. The increase of plant tolerance towards environmental stresses would open much opportunity for successful plant cultivation in these areas that were previously considered as ineligible, e.g. in areas with poor irrigation. In this study, we performed functional analysis of proteins encoded by PHYTOALEXIN DEFICIENT 4 (PAD4), LESION SIMULATING DISEASE 1 (LSD1) and ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) genes to explain their role in drought tolerance and biomass production in two different species: Arabidopsis thaliana and Populus tremula × tremuloides. Arabidopsis mutants pad4-5, lsd1-1, eds1-1 and transgenic poplar lines PAD4-RNAi, LSD1-RNAi and ESD1-RNAi were examined in terms of different morphological and physiological parameters. Our experiments proved that Arabidopsis PAD4, LSD1 and EDS1 play an important role in survival under drought stress and regulate plant vegetative and generative growth. Biomass production and acclimatory strategies in poplar were also orchestrated via a genetic system of PAD4 and LSD1 which balanced the cell division and cell death processes. Furthermore, improved rate of cell division/cell differentiation and altered physical properties of poplar wood were the outcome of PAD4- and LSD1-dependent changes in cell wall structure and composition. Our results demonstrate that PAD4, LSD1 and EDS1 constitute a molecular hub, which integrates plant responses to water stress, vegetative biomass production and generative development. The applicable goal of our research was to generate transgenic plants with regulatory mechanism that perceives stress signals to optimize plant growth and biomass production in semi-stress field conditions.
