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(SD2020-397) Identification of the plant stomatal CO2 sensor and uses thereof

Drs. Schroeder and Takahashi of UC San Diego have discovered and characterized a stomatal CO2 sensor and the underlying mechanism in plants. This unique plant CO2 sensor shows very strong phenotypes in mutants, with complete lack of a CO2 response. Moreover, the researchers can reconstitute this CO2 sensor with the recombinant protein complex in vitro. They are using this discovery to further develop genetic applications to modify CO2 sensing and water use efficiency in plants. The researchers have identified two protein kinases, which regulate a Raf-like protein kinase which in turn controls another Raf-like kinase activity in response to change in CO2/bicarbonate concentration in vitro. Mutants in each of these proteins completely disrupt CO2 responses in plants, consistent with our CO2 sensor findings. Biochemical structure analyses reveal important phosphorylation sites and provide insight into the direct CO2 sensing and signaling core mechanism in plant cells.

Rice Suberin Regulators For Abiotic Stress Tolerance

Professor Julia Bailey-Serres and colleagues from the University of California, Riverside have identified transcription factors involved in the synthesis and modulation of suberin in plants. These transcription factors can be gene-edited or otherwise engineered in rice or other monocot crops to alter suberin production – which can lead to development of new rice cultivars with enhanced tolerance to stresses ranging from increased soil salinity to drought to pest. Fig 1: Fluorol Yellow (FY) staining of rice crown roots for suberin in longitudinal views of the exodermis and radial cross sections under environmental conditions of well-watered (CON) or water deficit (WD).

Novel Genetic Switch for Inducing Gene Expression

Prof. Sean Cutler and colleagues at the University of California, Riverside have engineered a system and methods to induce gene expression in plants and organisms, including mammals, using the chemical compound mandipropamid. Using the PYR/PYL/HAB1 promoter system, the PYR1/HAB1 system is reprogrammed to be activiated with mandipropamid.  When the PYR1/HAB1 system dimerizes through chemical induced dimerization (CID) with mandipropamid, the system functions as a control switch for gene expression. This technology has been demonstrated to advantageously accelerate citrus breeding.  It may be applied to improve CAR T-cell therapy and agricultural crops. Fig 1: UCR’s PYR1/HAB1 system is programmed through chemical induced dimerization (CID) initiated by mandipropamid to function as a switch for agrochemical control of gene expression.  

Novel Citrus Genetic Immune Regulators For Defense Against Huanglongbing Disease

Prof. Hailing Jin and colleagues from the University of California, Riverside have identified genetic negative immune regulators that control the natural immune responses in citrus against HLB. Decreasing or removing these immune regulators may lead to citrus plants that are tolerant and/or resistance to HLB. The development of HLB resistant citrus plants is less expensive and a more efficient long term solution compared to current HLB management strategy, which includes removing infected trees and/or applying pesticides to lower the ACP population. Fig 1:Nicotiana benthamiana (Nb) model plants after exposure to HLB-like infection for 5 days. The plant with its VAD gene knocked-down (siVAD) expresses resistance to the HLB-like infection. The control plant (iRB control) is pictured on the left and is less resistant to the HLB-like infection. 

Gene Editing for Improved Plant Characteristics via Modulation of Suberin Regulators

Researchers at the University of California, Davis have identified specific genetic modifications to plants that impart a variety of advantages based on modulating the presence of suberin

Pepper Plant with Abscising Fruit and Petiole for Easy Harvest

Researchers at the University of California, Davis have developed a pepper plant that abscises its pedicel easily during harvesting, also known as destemming or decapping.

Plants with Enhanced Immunity to Root Knot Nematodes

Prof. Kaloshian and her colleagues from the University of California, Riverside, have developed plants with enhanced immunity resulting in enhanced resistance to RKNs. The methods comprise introducing into a plant a gene editing construct that specifically inhibits activity of G-LecRK-VI.13 gene, a negative regulator of plant immunity. Additionally, the descendant of this plant also carry the enhanced resistance to RKNs. The invention could be used in a broad range of important agricultural crops including rice, lettuce, and tomatoes. This approach holds potential for increasing crop quality and yield, considering that plant damage from RKNs result in poor growth, a decline in quality and yield of the crop, and reduced resistance to environmental stresses. By triggering an enhanced immune response, by eliminating a negative regulator of immunity, the opportunity exists to develop more durable plant resistance towards RKNs and other types of nematodes.  Fig 1: Tomato plants, grown in a plastic house, infected with the root-knot nematode Meloidogyne incognita.  

(SD2019-269) Use of M3K-delta Protein for Improvement of Plant Drought and Salinity Stress Resistance

The response of plants to reduced water availability is controlled by a complex osmotic stress and abscisic acid (ABA)-dependent signal transduction network. The core ABA signaling components are snf1-related protein kinase2s (SnRK2s) which are activated by ABA-dependent inhibition of type 2C protein phosphatases and by an unknown ABA-independent osmotic stress signaling pathway. Limited water availability is one of the key factors that negatively impacts crop yields. The plant hormone abscisic acid (ABA) and the signal transduction network it activates, enhance plant drought tolerance through stomatal closure, and inhibition of seed germination and growth. As plants are constantly exposed to changing water conditions, reversibility and robustness of the ABA signal transduction cascade is important for plants to balance growth and drought stress resistance. Core ABA signaling components have been established the ABA receptors PYRABACTIN RESISTANCE (PYR/PYL) or REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) inhibit type 2C protein phosphatases (PP2Cs) resulting in the activation of the SnRK2 protein kinases SnRK2.2, 2.3 and OST1/SnRK2.6 . However, it has remained unclear whether direct autophosphorylation or trans-phosphorylation by unknown protein kinases re-activates these SnRK2 protein kinases in response to stress. The osmotic stress sensing mechanism and upstream signal transduction mechanisms leading to SnRK2 activation remain largely unknown in plants.

Plants Resistant to Fungal Disease

University of California, Riverside researcher Prof. Hailing Jin and her colleagues have developed plants that are resistant to Botrytis cineria. These plants are genetically engineered to silence fungal pathogens that transfer “virulent” small RNA effectors to the plant that cause disease.  This has led to the development of plants that are resistant to Botrytis cineria. Fig. 1 shows that transgenic plants exhibited reduced disease susceptility to Botrytis cineria when compared with the wild type. Fig. 2 shows that lesion size and fungal biomass of at least 20 leaves were reduced in the transgenic plant when compared to the wild type. Measurements were take at 96 hours after exposure to Botrytis cineria.    

Improved Plant Regeneration Method Using GRFs, GIFs or Chimeric GRF-GIF Proteins

Researchers at the University of California, Davis and the Institute of Molecular and Cellular Biology of Rosario in Argentina have collaborated to develop methods for improving plant regeneration efficiency using transformations via a GRF, a GIF, or a GRF-GIF chimera. 

Improved Cas12a Proteins for Accurate and Efficient Genome Editing

Mutated versions of Cas12a that remove its non-specific ssDNA cleavage activity without affecting site-specific double-stranded DNA cutting activity. These mutant proteins, in which a short amino acid sequence is deleted or changed, provide improved genome editing tools that will avoid potential off-target editing due to random ssDNA nicking.

Modified Enzymes to Improve Crop Yield

Researchers at the University of California have identified new modified versions of the carbon fixing enzyme, Phosphoenolpyruvate carboxylase (PPC).  in planta results show that the modified PPC enzymes confer upwards of a five fold increase in carbon fixation when compared to wild type plants. PPC dependent carbon fixation is key to photosynthesis, production of nutrients, and plants conditioning their growth environment. Plants with modified PPCs that increase carbon fixation and photosynthetic output will have increased plant productivity, which is critical for feeding a growing population. Additionally, by identifying surgical changes that can unleash the full productivity of plant PPC’s, it will be possible to increase the rate of depletion of atmospheric CO2.  The combination of these outcomes represents the opportunity to boost agricultural productivity, increase the amount of agriculturally available land by upwards of 100%, and improve the nutritional quality of plants all of which are dependent on removal of CO2 from our atmosphere.  Fig. 2 in vitro comparison of wild type (wt) and modified versions of maize PPC1, which is key to C4 photosynthesis, in the absence or presence of increasing amounts of the allosteric inhibitor, malate. Whereas version A is less affected by malate than wt, both versions B and C are largely unaffected by malate and have a 2-fold increase in activity compared to the wt version.  

Inducible N-Degron Mediated Haploid Induction

Researchers at the University of California, Davis have developed a method of cell-specific degradation of centromeric proteins to induce haploid.

Compound that Regulates Brassinosteroid Response

Background: Brassinosteroids are essential plant hormones that control growth and development, in addition to playing a critical role in response to stress and infections. Brassinosteroids also induce ethylene synthesis and are therefore related to senescence and ripening. The major overarching issue involves strictly controlling brassinosteroid response in order to promote growth yet limit other negative effects of brassinosteroids.  Brief Description: UCR researchers have identified three compounds that alter brassinosteroid signaling in plants. These chemicals were found to increase the effects of limited brassinosteroids found under normal conditions yet reduce the effects of excess brassinosteroids. This includes promotive effects on plant height, which increase by 100% due to the chemical enhancing the impact of endogenous brassinosteroids. In contrast, the extreme effects seen with addition of high levels of brassinosteroids are substantially reduced upon addition of this chemical, indicating that this chemical may be useful for modulating the effects of brassinosteroids. In conjunction with this, treatment with the chemical resulted in reversal of several ethylene dependent growth phenomena that are also regulated by brassinosteroids. Currently, there is a huge unmet need in the agricultural sector since treatments that modulate brassinosteroid-regulated phenomena do not exist.

Drug-Like Compounds That Enhance Plant Immunity And Growth

Background: Due to the rapidly increasing demand of food production, agricultural biotechnology companies are aiming to improve crop productivity. Biotechnology tools that develop novel plant traits are projected to have a $1.3B global market with annual growth of 49.9% by 2019.  Brief Description: UCR Researchers have developed a drug-like compound, HTC, that is structurally distinct from other agrochemicals and will rapidly induce an immune response in plants to ward off pathogens. Only a small dose of this novel compound is needed for optimal protection as well as growth enhancement. By genetically engineering the plant to have a stronger inherent immune system, toxic chemicals like pesticides are no longer needed to protect the plant. Its implementation can render decreased usage of agrochemicals that are harmful to humans and the environment.

High Transformation Efficiency Non-Dormant Alfalfa Line 2525-14

Researchers at UC Davis have produced a non-dormant alfalfa line highly amenable to transformation, allowing direct improvement of the line. Higher transformation efficiency and a non-dormant life-cycle make this line of alfalfa a valuable tool for research and breeding.

Diagnostics for Citrus Greening Disease

Background: Citrus greening disease, also known as Huanglongbing (HLB), is a bacterial disease caused by insect-transmission and phloem-limited bacterial pathogens. It is a serious threat to the global citrus industry, decimating many citrus trees and costing the economy billions in damages annually. The most commonly used method of nucleic-acid based pathogen detection is not ideal with low-titer (low concentration of antibodies to antigen) and it cannot detect the erratic distribution of the bacterial pathogens.   Brief Description: UCR researchers have developed a proof-of-concept for using secreted proteins of bacterial pathogens to detect bacterial diseases. These abundant and stable secreted proteins serve as robust detection markers for immunoassay-based diagnostics. Compared to current methods, this novel method is more high-throughput, economical, and able to monitor the pathogens dispersed throughout the plant transportation system.

Novel Multiplex Assay Detects Citrus Pathogens

Background: Citrus greening disease, also known as huanglongbing (HLB), has been a serious, pervasive problem caused by a multitude of plant pathogens. It has decimated many citrus trees, drastically decreasing orange production and costing the US economy an estimated $11B every year. Currently, there is no cure for HLB, so the citrus industry is in dire need for a cost-effective method of early HLB detection.  Brief Description: UCR Researchers have developed a means to detect and identify multiple plant pathogens for disease diagnosis, including citrus greening disease. By developing a novel multiplex RNA assay, they discovered ten targets of nine citrus pathogens and a citrus control gene. In addition to the assays, target-specific probes were designed and implemented to improve the pathogen detection process. These assays were also coupled with high-throughput robotic extraction and purification procedures, optimized for citrus tissues. Furthermore, they also developed a 3-plex DNA assay system along with 3 targets for simultaneous detection, identification and quantification of plant pathogens.

Novel Peptide Capable of Stimulating Disease Resistance in Plants

Pamela Ronald and researchers at the Joint BioEnergy Institute (JBEI) have discovered raxX, a novel peptide that activates the Xa21 immune response pathway, capable of conferring robust disease resistance, and methods for its use. Application of the peptide activates the plant immune responses and eliminating bacterial infection. Engineering plants to express both raxX and Xa21 under an inducible control is expected to lead to robust resistance in diverse plant species.

Novel Methods and Compositions for Epigenetic Gene Silencing in Plants

Dr. Steve Jacobsen and colleagues in UCLA’s Department of Molecular, Cell, and Developmental Biology and the Howard Hughes Medical Institute have developed novel methods and compositions for targeted genetic repression in plants. The technology has broad agricultural applications.    

Improved Xylan Extraction

Brief description not available

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