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.

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.    

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. 

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.

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.  

Researchers at the University of California, Davis have developed a method to produce haploid progeny plants from transgenic and wild-type plants that only carry chromosomes from the wild-type gamete.

Researchers at the University of California, Davis have developed a method to propagate hybrid crops through seeds that allow for the fixation of hybrid vigor.

Researchers at the University of California, Davis have developed a guided nuclease based expression system to introduce genetic modifications into plants without the need for tissue culture.

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

UCLA researchers in the Department of Molecular, Cell, and Developmental Biology have developed a method to specifically suppress the highly efficient non-homologous end joining (NHEJ) pathway to boost homologous recombination efficiency in plants.

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Background: California is one of the largest citrus producers in the world, and the demand for fresh citrus fruit that is seedless or low-seeded is on the rise. ‘Kinnow’ is the currently popular mandarin cultivar that covers 80% of all citrus trees in the Middle Eastern regions. Despite its fecundity in this region, it is very seedy and contains about 15-30 seeds per fruit. Therefore, there is high demand for mandarins that can not only withstand diverse climate conditions but have a low seed count.  Brief Description: ‘KinnowLS’ is a mandarin selection developed by mutation breeding of the diploid mandarin cultivar ‘Kinnow’, having only two to three seeds per fruit in all situations of cross-pollination. It is a mid- to late-season maturing diploid mandarin that combines large-sized fruit of excellent quality and production with low seed content even in mixed plantings. ‘KinnowLS’ exhibits vertical tree growth habits, which allows it to produce a large and dense crown. This novel hybrid could be successful in a mid-to-late season marketing window which currently has few low-seeded, high quality cultivars.

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.

Researchers at the University of California, Davis have identified non-transgenic mutant plants capable of generating haploid offspring.

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Background: Lipids (oils) produced by plants and photosynthetic microorganisms are used for general cooking, health food, cosmetics, pharmaceuticals and biodiesel. The current methods to produce oils with photosynthetic microorganisms are inefficient, since the cells must undergo extreme stress for lipid droplet (LD) accumulation and then be killed for extraction. Accumulation of LDs in the cytosol generates metabolic feedback inhibition. Some of these problems also apply to oil production with plants. A more efficient production practice is needed to meet high consumer and commercial demands.  Brief Description: UCR researchers have developed a method to optimize oil synthesis in microorganisms and plants by redirecting cytosolic LDs to the cell vacuoles. They successfully identified and modified a specific protein involved in directing lipids to various areas within the cell. Through restructuring and adding novel peptides, researchers were then able to re-route the fate of lipids into vacuoles (storage warehouses), thus eliminating metabolic feedback inhibition. Currently, they are also working towards achieving redirection of lipids to the cell exterior for excretion.

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.

Background: Citrus greening disease, also known as huanglongbing (HLB), is a stubborn bacterial disease caused by insect-transmission and phloem-limited bacterial pathogens. It has been a serious threat to the US citrus industry, decimating many citrus trees and costing the economy $11B in damages annually. The most commonly used method of nucleic-acid based pathogen detection has issues with low-titer (low concentration of antibodies to antigen) and cannot handle the erratic distribution of the 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.

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.

Background: Over the years, the world renowned Citrus Experiment Station became the foundation of  the UC Riverside campus, where citrus breeding and agricultural research remain at the forefront.  UCR’s premier citrus breeding program varieties are  licensed worldwide, and some have been considered by professional taste panels to be one of the best flavored citrus in the world. Description: ‘FairchildLS,’  a mandarin developed by mutation breeding, is  seedless or low-seeded in all situations of cross-pollination. It has a moderately smooth texture and a sweet, rich fruit flavor. Easy to peel and with a deep orange color, the ‘FairchildLS’ is an attractive citrus that is popular and sought-out by the citrus industry. 

Background: California is one of the largest citrus producers in the world, and the demand for fresh citrus fruit that is seedless or low-seeded is on the rise. W. Murcott mandarin is the currently popular mandarin cultivar that has been known worldwide for its high quality and about 2-3 million trees have been widely planted throughout California over the past decade. Unfortunately, isolation of citrus orchards have been difficult and consequently, W. murcott mandarins have become very seedy due to cross pollination by other citrus varieties. Therefore, consumer demands for mandarins that can maintain a low seed count and high-quality is increasing.  Brief Description: UCR researchers developed the ‘Gold Nugget’ mandarin which is a hybrid of ‘Wilking’ and ‘Kincy’ mandarins. that has a deep orange colored flesh, extremely fine texture, and is low-seeded in all situations of cross pollination. This medium sized mandarin grows vigorously in upright form and has outstanding storage characteristics on its trees. It matures in mid- to late-season.

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.

Researchers at UC Davis have discovered methods of selecting plants with targeted genome edits without resorting to tissue culture or selectable transgenes. The resulting method is a non-transgenic approach that avoids the off-target background mutations generated by selection in tissue culture.

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