Researchers at UC Berkeley have developed methods to deliver biomolecules to plant cells using new plant-derived cell penetrating peptides (CPPs). Despite the revolution in DNA editing that the last decade has brought, plant genetic engineering has not been able to benefit to the same extent. This is due to certain challenges in plant physiology that limit the delivery of exogenous protein cargos, as required in the CRISPR-Cas9 system, primarily due to the plant cell wall. In mammalian cells, for instance, cargo delivery can be accomplished using cell-penetrating peptides (CPPs) which are short peptides that facilitate the transport of cargo molecules through the plasma membrane to the cytosol. While this technology has been optimized in mammalian cells, few have studied the delivery of CPPs in plants to verify whether the cell wall is permissible to these materials. Another barrier to the use of nanotechnologies for plant biomolecule delivery is the lack of quantitative validation of successful intracellular protein delivery. The near universal dependence on confocal microscopy to validate delivery of fluorescent proxy cargoes can be inappropriate for use in plants due to various physiological plant properties, for example intrinsic autofluorescence of plant tissues. Therefore, there exists an unmet need for new materials and methods to deliver biomolecules to plant cells and to confirm the delivery of proteins of varying sizes into walled plant tissues. Stage of Research The inventors have developed methods to deliver proteins into plant cells using cell penetrating peptides which are appropriate for use with CRISPR-Cas9 technology, siRNAs, zinc-finger nucleases, TALENs, and other DNA editing methods. They have also developed a biomolecule fluorophore-based assay to accurately quantitate protein delivery to plants cells.Stage of DevelopmentResearch - in vitro 

Within the plant kingdom, a wide variety of species possess an extraordinary ability to regenerate whole organs and tissues naturally. Invasive weeds such as Japanese knotweed can regenerate from tiny root fragments in the soil, and many gardeners’ favorites can be propagated by taking cuttings from fully-grown plants. However, this flexible ability to regenerate organs is missing from most economically important crop species, and is currently the single biggest bottleneck for plant biotechnology.  While there is an increasingly impressive array of tools to edit the genes of a plant cell, regenerating whole organs and body plans from edited cells via labor-intensive tissue culture remains a painstaking process – often requiring a year or more – and resulting in undesirable mutations and chromosome instability.  UCB researchers have discovered that complete genetic knockout of the DNA demethylation pathway in the model plant Arabidopsis dramatically enhances the ability of plant organs to regenerate after wounding. In many plants, including Arabidopsis, regeneration after wounding does not occur naturally and requires intensive tissue culture. By contrast, quadruple homozygous mutant plants harboring loss of function mutations to all four DNA demethylase enzymes capably regenerate all organs and complete body plans after cutting, even in the absence of exogenous plant hormones and tissue culture. 

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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

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, Davis have developed a method of cell-specific degradation of centromeric proteins to induce haploid.

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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. 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: ‘Tango’ is a mandarin selection developed by mutation breeding and is seedless or low-seeded in all situations of cross-pollination. It is a mid- to late-season irradiated selection of W. Murcott mandarin that has a rich, sweet and juicy flavor. With a deep orange color and easy-to-peel rind, ‘Tango’ is n attractive citrus that is popular and sought-out by the citrus industry. ‘Tango’ also exhibits excellent vertical tree growth habits, which allows it to produce a large and dense crown. For multiple generations, this mandarin selection has remained true-to-type for low seed content and its other traits.

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.

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.

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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 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.

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.

Researchers at the University of California, Davis have developed methods for improving fruit quality by introgressing genes encoding specific transcription factors into the plant.

In many agricultural seed products—such as oilseed crops, grains and legumes, and seeds harvested specifically for planting—premature release of seeds prior to harvest results in serious losses. Swathing and other methods for minimizing harvest loses add to overall production costs. In addition, regardless of cost factors, the need for positive control of seed release may in future years become a desirable capability when genetically modified organism (GMO) crops become widespread, in order to assure satisfactory containment.

A chemically inducible cucumber mosaic virus amplicon expression system for the production of recombinant proteins in plant-based systems.

Light-Independent Phytochrome Signaling

Constitutive Promoter in Dicot Plants