Drought resistance by engineering plant tissue-specific responses

Altres ajuts: CERCA Programme/Generalitat de CatalunyaDrought is the primary cause of agricultural loss globally, and represents a major threat to food security. Currently, plant biotechnology stands as one of the most promising fields when it comes to developing crops that are able to produce high yields in water-limited conditions. From studies of Arabidopsis thaliana whole plants, the main response mechanisms to drought stress have been uncovered, and multiple drought resistance genes have already been engineered into crops. So far, most plants with enhanced drought resistance have displayed reduced crop yield, meaning that there is still a need to search for novel approaches that can uncouple drought resistance from plant growth. Our laboratory has recently shown that the receptors of brassinosteroid (BR) hormones use tissue-specific pathways to mediate different developmental responses during root growth. In Arabidopsis, we found that increasing BR receptors in the vascular plant tissues confers resistance to drought without penalizing growth, opening up an exceptional opportunity to investigate the mechanisms that confer drought resistance with cellular specificity in plants. In this review, we provide an overview of the most promising phenotypical drought traits that could be improved biotechnologically to obtain drought-tolerant cereals. In addition, we discuss how current genome editing technologies could help to identify and manipulate novel genes that might grant resistance to drought stress. In the upcoming years, we expect that sustainable solutions for enhancing crop production in water-limited environments will be identified through joint efforts

Silencing of ATI genes involved in adverse reactions to wheat by RNAi and CRISPR-Cas9 technologies

Although wheat is consumed worldwide as a staple food, it can give rise to different adverse reactions, some of which have not been deeply characterized. They are caused mainly by wheat proteins, both gluten and non-gluten proteins. Structural and metabolic proteins, like \u3b1amylase/trypsin inhibitors (ATI) are involved in the onset of wheat allergies (bakers\u2019 asthma) and probably non-coeliac wheat sensitivity (NCWS). The ATI are encoded by a multigene family dispersed over several. Notably, WTAI-CM3 and WTAI-CM16 subunits are involved in the onset of bakers\u2019 asthma and are likely to contribute to NCWS. In this study we report the RNAi silencing of WTAI-CM3, WTAI-CM16 and WMAI-0.28 genes in the bread wheat cultivar Bobwhite and the CRISPR/Cas9 mediated gene knockout of WTAI-CM3 and WTAI-CM16 in the durum wheat cultivar Svevo. We have obtained different RNAi transgenic lines showing an effective decrease in the expression in the targeted genes. These lines do not show differences in terms of yield, but have unintended effects on the accumulation of the high molecular weight glutenin subunits which play a crucial role in the technological performances of wheat flour. Furthermore, the editing of WTAI-CM3 and WTAI-CM16 genes was obtained through a CRISPR-Cas9 multiplexing strategy in the Italian durum wheat cultivar Svevo with a marker-free approach. The regeneration of plants without selection agents allowed T0 homozygous mutant plants to be obtained without the integration in the wheat genome of CRISPR/Cas9 vectors, demonstrating the capability of CRISPR technology to produce wheat lines in a reduced time compared to conventional breeding approaches. The possibility to develop new wheat genotypes accumulating a lower amount of proteins effectively involved in such pathologies, not only offers the possibility to use them as a basis for the creation of wheat varieties with a lower impact on adverse reactions, but also to test if these proteins are actually implicated in those pathologies for which the triggering factor has yet to be established

From Arabidopsis to Sorghum drought resistant plants: it's a long way to the crop

Trabajo presentado al Internal Seminar of the Centre de Recerca Agrigenómica (CRAG), celebrado el 15 de noviembre de 2019

How Changes in ABA Accumulation and Signaling Influence Tomato Drought Responses and Reproductive Development

Water deficit conditions trigger the production of a chemical signal, the phytohormone abscisic acid (ABA), which coordinates multiple responses at different temporal and spatial scales. Despite the complexity of natural drought conditions, the modulation of ABA signaling could be harnessed to ameliorate the drought performances of crops in the face of increasingly challenging climate conditions. Based on recent studies, increasing ABA sensitivity can lead to genotypes with improved drought resistance traits, with sustained biomass production in water-limiting environments and little or no costs with respect to biomass production under optimal conditions. However, variations in ABA production and sensitivity lead to changes in various aspects of reproductive development, including flowering time. Here we provide an updated summary of the literature on ABA-related genes in tomato and discuss how their manipulation can impact water-deficit-related responses and/or other developmental traits. We suggest that a better understanding of specific ABA components’ function or their expression may offer novel tools to specifically engineer drought resistance without affecting developmental traits

The four FAD-dependent histone demethylases of arabidopsis are differently involved in the control of flowering time

In Arabidopsis thaliana, four FAD-dependent lysine-specific histone demethylases (LDL1, LDL2, LDL3, and FLD) are present, bearing both a SWIRM and an amine oxidase domain. In this study, a comparative analysis of gene structure, evolutionary relationships, tissue- and organ-specific expression patterns, physiological roles and target genes for the four Arabidopsis LDL/FLDs is reported. Phylogenetic analysis evidences a different evolutionary history for the four LDL/FLDs, while promoter activity data show that LDL/FLDs are strongly expressed during plant development and embryogenesis, with some gene-specific expression patterns. Furthermore, phenotypical analysis of loss-of-function mutants indicates a role of all four Arabidopsis LDL/FLD genes in the control of flowering time, though for some of them with opposing effects. This study contributes toward a better understanding of the LDL/FLD physiological roles and may provide biotechnological strategies for crop improvement

The four FAD-dependent histone demethylases of arabidopsis are differently involved in the control of flowering time

In Arabidopsis thaliana, four FAD-dependent lysine-specific histone demethylases (LDL1, LDL2, LDL3, and FLD) are present, bearing both a SWIRM and an amine oxidase domain. In this study, a comparative analysis of gene structure, evolutionary relationships, tissue- and organ-specific expression patterns, physiological roles and target genes for the four Arabidopsis LDL/FLDs is reported. Phylogenetic analysis evidences a different evolutionary history for the four LDL/FLDs, while promoter activity data show that LDL/FLDs are strongly expressed during plant development and embryogenesis, with some gene-specific expression patterns. Furthermore, phenotypical analysis of loss-of-function mutants indicates a role of all four Arabidopsis LDL/FLD genes in the control of flowering time, though for some of them with opposing effects. This study contributes toward a better understanding of the LDL/FLD physiological roles and may provide biotechnological strategies for crop improvement

Transcriptional and Post-transcriptional Mechanisms Limit Heading Date 1 (Hd1) Function to Adapt Rice to High Latitudes

Rice flowering is controlled by changes in the photoperiod that promote the transition to the reproductive phase as days become shorter. Natural genetic variation for flowering time has been largely documented and has been instrumental to define the genetics of the photoperiodic pathway, as well as providing valuable material for artificial selection of varieties better adapted to local environments. We mined genetic variation in a collection of rice varieties highly adapted to European regions and isolated distinct variants of the long day repressor HEADING DATE 1 (Hd1) that perturb its expression or protein function. Specific variants allowed us to define novel features of the photoperiodic flowering pathway. We demonstrate that a histone fold domain scaffold formed by GRAIN YIELD, PLANT HEIGHT AND HEADING DATE 8 (Ghd8) and several NF-YC subunits can accommodate distinct proteins, including Hd1 and PSEUDO RESPONSE REGULATOR 37 (PRR37), and that the resulting OsNF-Y complex containing Hd1 can bind a specific sequence in the promoter of HEADING DATE 3A (Hd3a). Artificial selection has locally favored an Hd1 variant unable to assemble in such heterotrimeric complex. The causal polymorphism was defined as a single conserved lysine in the CCT domain of the Hd1 protein. Our results indicate how genetic variation can be stratified and explored at multiple levels, and how its description can contribute to the molecular understanding of basic developmental processes

Exploring the role of brassinosteroids in the primary root growth and development of the primary embryonic root of Sorghum bicolor

Resumen del póster presentado al Congreso 'At the Forefront of Plant Research', celebrado en Barcelona (España) del 6 al 8 de mayo de 2019.Brassinosteroids (BRs) are steroid hormones essential for plant growth and development as well as for the adaptation to drought. A wealth of studies report the importance of BRs in superior plants, mostly Arabidopsis. How BRs modulate root formation and adaptation to abiotic stress in monocot cereals awaits to be understood. In this study, we explore the role of BRs in root growth and development in cereal Sorghum bicolor. We focus on the analysis of embryonic roots by implementing a set of in vitro and microscopy techniques, such as mPS-PI and EdU staining. Our analysis reveals the organization of the primary root in how different cell types at the root apex behave in response to BRs and abiotic stress. In addition, we used a mutant collection of Sorghum bicolor to identify a number of mutants in BR signalling components. Mutant analysis will be key to begin to decipher the role of BRs in sorghum primary root growing in normal and stress conditions, and will be instrumental for their future improvement.Peer reviewe