TY - JOUR AB - Plants are continuously exposed to a myriad of external signals such as fluctuating nutrients availability, drought, heat, cold, high salinity, or pathogen/pest attacks that can severely affect their development, growth, and fertility. As sessile organisms, plants must therefore be able to sense and rapidly react to these external inputs, activate efficient responses, and adjust development to changing conditions. In recent years, significant progress has been made towards understanding the molecular mechanisms underlying the intricate and complex communication between plants and the environment. It is now becoming increasingly evident that hormones have an important regulatory role in plant adaptation and defense mechanisms. AU - Benková, Eva ID - 1269 IS - 6 JF - Plant Molecular Biology TI - Plant hormones in interactions with the environment VL - 91 ER - TY - JOUR AB - Lateral root primordia (LRP) originate from pericycle stem cells located deep within parental root tissues. LRP emerge through overlying root tissues by inducing auxin-dependent cell separation and hydraulic changes in adjacent cells. The auxin-inducible auxin influx carrier LAX3 plays a key role concentrating this signal in cells overlying LRP. Delimiting LAX3 expression to two adjacent cell files overlying new LRP is crucial to ensure that auxin-regulated cell separation occurs solely along their shared walls. Multiscale modeling has predicted that this highly focused pattern of expression requires auxin to sequentially induce auxin efflux and influx carriers PIN3 and LAX3, respectively. Consistent with model predictions, we report that auxin-inducible LAX3 expression is regulated indirectly by AUXIN RESPONSE FACTOR 7 (ARF7). Yeast one-hybrid screens revealed that the LAX3 promoter is bound by the transcription factor LBD29, which is a direct target for regulation by ARF7. Disrupting auxin-inducible LBD29 expression or expressing an LBD29-SRDX transcriptional repressor phenocopied the lax3 mutant, resulting in delayed lateral root emergence. We conclude that sequential LBD29 and LAX3 induction by auxin is required to coordinate cell separation and organ emergence. AU - Porco, Silvana AU - Larrieu, Antoine AU - Du, Yujuan AU - Gaudinier, Allison AU - Goh, Tatsuaki AU - Swarup, Kamal AU - Swarup, Ranjan AU - Kuempers, Britta AU - Bishopp, Anthony AU - Lavenus, Julien AU - Casimiro, Ilda AU - Hill, Kristine AU - Benková, Eva AU - Fukaki, Hidehiro AU - Brady, Siobhan AU - Scheres, Ben AU - Peéet, Benjamin AU - Bennett, Malcolm ID - 1273 IS - 18 JF - Development TI - Lateral root emergence in Arabidopsis is dependent on transcription factor LBD29 regulation of auxin influx carrier LAX3 VL - 143 ER - TY - JOUR AB - Plants are able to modulate root growth and development to optimize their nitrogen nutrition. In Arabidopsis (Arabidopsis thaliana), the adaptive root response to nitrate (NO3 -) depends on the NRT1.1/NPF6.3 transporter/sensor. NRT1.1 represses emergence of lateral root primordia (LRPs) at low concentration or absence of NO3 - through its auxin transport activity that lowers auxin accumulation in LR. However, these functional data strongly contrast with the known transcriptional regulation of NRT1.1, which is markedly repressed in LRPs in the absence of NO3 -. To explain this discrepancy, we investigated in detail the spatiotemporal expression pattern of the NRT1.1 protein during LRP development and combined local transcript analysis with the use of transgenic lines expressing tagged NRT1.1 proteins. Our results show that although NO3 - stimulates NRT1.1 transcription and probably mRNA stability both in primary root tissues and in LRPs, it acts differentially on protein accumulation, depending on the tissues considered with stimulation in cortex and epidermis of the primary root and a strong repression in LRPs and to a lower extent at the primary root tip. This demonstrates that NRT1.1 is strongly regulated at the posttranscriptional level by tissue-specific mechanisms. These mechanisms are crucial for controlling the large palette of adaptive responses to NO3 - mediated by NRT1.1 as they ensure that the protein is present in the proper tissue under the specific conditions where it plays a signaling role in this particular tissue. AU - Bouguyon, Eléonore AU - Perrine Walker, Francine AU - Pervent, Marjorie AU - Rochette, Juliette AU - Cuesta, Candela AU - Benková, Eva AU - Martinière, Alexandre AU - Bach, Lien AU - Krouk, Gabriel AU - Gojon, Alain AU - Nacry, Philippe ID - 1281 IS - 2 JF - Plant Physiology TI - Nitrate controls root development through posttranscriptional regulation of the NRT1.1/NPF6.3 transporter sensor VL - 172 ER - TY - JOUR AB - The impact of the plant hormone ethylene on seedling development has long been recognized; however, its ecophysiological relevance is unexplored. Three recent studies demonstrate that ethylene is a critical endogenous integrator of various environmental signals including mechanical stress, light, and oxygen availability during seedling germination and growth through the soil. AU - Zhu, Qiang AU - Benková, Eva ID - 1283 IS - 10 JF - Trends in Plant Science TI - Seedlings’ strategy to overcome a soil barrier VL - 21 ER - TY - JOUR AB - Cytokinin is a phytohormone that is well known for its roles in numerous plant growth and developmental processes, yet it has also been linked to abiotic stress response in a less defined manner. Arabidopsis (Arabidopsis thaliana) Cytokinin Response Factor 6 (CRF6) is a cytokinin-responsive AP2/ERF-family transcription factor that, through the cytokinin signaling pathway, plays a key role in the inhibition of dark-induced senescence. CRF6 expression is also induced by oxidative stress, and here we show a novel function for CRF6 in relation to oxidative stress and identify downstream transcriptional targets of CRF6 that are repressed in response to oxidative stress. Analysis of transcriptomic changes in wild-type and crf6 mutant plants treated with H2O2 identified CRF6-dependent differentially expressed transcripts, many of which were repressed rather than induced. Moreover, many repressed genes also show decreased expression in 35S:CRF6 overexpressing plants. Together, these findings suggest that CRF6 functions largely as a transcriptional repressor. Interestingly, among the H2O2 repressed CRF6-dependent transcripts was a set of five genes associated with cytokinin processes: (signaling) ARR6, ARR9, ARR11, (biosynthesis) LOG7, and (transport) ABCG14. We have examined mutants of these cytokinin-associated target genes to reveal novel connections to oxidative stress. Further examination of CRF6-DNA interactions indicated that CRF6 may regulate its targets both directly and indirectly. Together, this shows that CRF6 functions during oxidative stress as a negative regulator to control this cytokinin-associated module of CRF6- dependent genes and establishes a novel connection between cytokinin and oxidative stress response. AU - Zwack, Paul AU - De Clercq, Inge AU - Howton, Timothy AU - Hallmark, H Tucker AU - Hurny, Andrej AU - Keshishian, Erika AU - Parish, Alyssa AU - Benková, Eva AU - Mukhtar, M Shahid AU - Van Breusegem, Frank AU - Rashotte, Aaron ID - 1331 IS - 2 JF - Plant Physiology SN - 0032-0889 TI - Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress VL - 172 ER -