Christopher T. Jackson

Bio: Christopher T. Jackson is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Population & Genome editing. The author has an hindex of 2, co-authored 5 publications receiving 19 citations.

Nanotechnology to advance CRISPR-Cas genetic engineering of plants.

Abstract: CRISPR-Cas genetic engineering of plants holds tremendous potential for providing food security, battling biotic and abiotic crop stresses caused by climate change, and for environmental remediation and sustainability. Since the discovery of CRISPR-Cas technology, its usefulness has been demonstrated widely, including for genome editing in plants. Despite the revolutionary nature of genome-editing tools and the notable progress that these tools have enabled in plant genetic engineering, there remain many challenges for CRISPR applications in plant biotechnology. Nanomaterials could address some of the most critical challenges of CRISPR genome editing in plants through improvements in cargo delivery, species independence, germline transformation and gene editing efficiency. This Perspective identifies major barriers preventing CRISPR-mediated plant genetic engineering from reaching its full potential, and discusses ways that nanoparticle technologies can lower or eliminate these barriers. We also describe advances that are needed in nanotechnology to facilitate and accelerate plant genome editing. Timely advancement of the application of CRISPR technologies in plant engineering is crucial for our ability to feed and sustain the growing human population under a changing global climate.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading

Abstract: Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethyleneimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the toxicity of polymer-based nanomaterials in plants and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Expanding access to electric vehicles in California’s low-income communities

Abstract: In September 2020, California Governor Gavin Newsom announced an ambitious executive order requiring all new passenger vehicles sold in the state to be zero-emission by 2035 (California Governor 2020). This action recognizes that the growing threats of climate change and local air pollution necessitate a rapid transition away from traditional internal combustion engine vehicles. In California, disadvantaged populations in particular face significant barriers, including financing and charging, to electric vehicle (EV) adoption. For the state to meet its clean energy goals, it must include these communities in a more just transition to widespread use of EVs. This should include avenues of support such as updating state building codes for multi-unit dwellings, where almost half of all Californians live. Charging site access must be increased through curbside infrastructure expansion and institution of statewide EV charger rebates. Finally, increased access to vehicles themselves should be facilitated by expanding incentives and formats for EV sharing programs.

Carbon nanotube biocompatibility in plants is determined by their surface chemistry

Abstract: Agriculture faces significant global challenges including climate change and an increasing food demand due to a growing population. Addressing these challenges will require the adoption of transformative innovations into biotechnology practice, such as nanotechnology. Recently, nanomaterials have emerged as unmatched tools for their use as biosensors, or as biomolecule delivery vehicles. Despite their increasingly prolific use, plant-nanomaterial interactions remain poorly characterized, drawing into question the breadth of their utility and their broader environmental compatibility. Herein, we characterize Arabidopsis thaliana transcriptional response to single walled carbon nanotubes (SWNTs) with two different surface chemistries commonly used for biosensing and nucleic acid delivery: oligonucleotide adsorbed-pristine SWNTs, and polyethyleneimine-SWNTs loaded with plasmid DNA (PEI-SWNTs), both introduced by leaf infiltration. We observed that SWNTs elicit a mild stress response almost undistinguishable from the infiltration process, indicating that these nanomaterials are well-tolerated by the plant. However, PEI-SWNTs induce a much larger transcriptional reprogramming that involves stress, immunity, and senescence responses. PEI-SWNT-induced transcriptional profile is very similar to that of mutant plants displaying a constitutive immune response or treated with stress-priming agrochemicals. We selected molecular markers from our transcriptomic analysis and identified PEI as the main cause of this reaction. We show that PEI-SWNT response is concentration-dependent and, when persistent over time, leads to cell death. We probed a panel of PEI variant-functionalized SWNTs across two plant species and identified biocompatible SWNT surface functionalizations. Our results highlight the importance of nanoparticle surface chemistry on their biocompatibility and will facilitate the use of functionalized nanomaterials for agricultural improvement. Significance statementNanomaterials can be used in agriculture as biosensors to monitor plant health, as fertilizers or growth regulators, and as delivery vehicles for genome engineering reagents to improve crops. However, the interactions between nanoparticles and plant cells are not well understood. Here, we characterize the plant transcriptomic response to single-walled carbon nanotubes (SWNTs) commonly used for sensing and nucleic acid delivery. While SWNTs themselves are well tolerated by plants, SWNTs surface-functionalized with positively charged polymers become toxic and produce cell death. We identify molecular markers of this toxic response to create biocompatible SWNT formulations. These results highlight the significance of nanoparticle surface chemistry, perhaps more than the nanoparticles themselves, on downstream interactions of nanoparticles with the environment.

Melatonin-mediated temperature stress tolerance in plants

Abstract: ABSTRACT Global climate changes cause extreme temperatures and a significant reduction in crop production, leading to food insecurity worldwide. Temperature extremes (including both heat and cold stresses) is one of the most limiting factors in plant growth and development and severely affect plant physiology, biochemical, and molecular processes. Biostimulants like melatonin (MET) have a multifunctional role that acts as a “defense molecule” to safeguard plants against the noxious effects of temperature stress. MET treatment improves plant growth and temperature tolerance by improving several defense mechanisms. Current research also suggests that MET interacts with other molecules, like phytohormones and gaseous molecules, which greatly supports plant adaptation to temperature stress. Genetic engineering via overexpression or CRISPR/Cas system of MET biosynthetic genes uplifts the MET levels in transgenic plants and enhances temperature stress tolerance. This review highlights the critical role of MET in plant production and tolerance against temperature stress. We have documented how MET interacts with other molecules to alleviate temperature stress. MET-mediated molecular breeding would be great potential in helping the adverse effects of temperature stress by creating transgenic plants.

Recent advances in nano-enabled agriculture for improving plant performance

Abstract: Nano-enabled agriculture is an emerging hot topic. To facilitate the development of nano-enabled agriculture, reviews addressing or discussing the applications, knowledge gap, future research needs, and possible new research field of plant nanobiotechnology in agricultural production are encouraged. Here we review the following topics in plant nanobiotechnology for agriculture: 1) improving stress tolerance, 2) stress sensing and early detection, 3) targeted delivery and controlled release of agrochemicals, 4) transgenic events in non-model crop species, and 5) seed nanopriming. We discuss the knowledge gaps in these topics. Besides the use of nanomaterials for harvesting more electrons to improve photosynthetic performance, they could be used to convert nIR and UV to visible light to expand the light spectrum for photosynthesis. We discuss this approach to maintaining plant photosynthesis under light-insufficient conditions. Our aim in this review is to aid researchers to learn quickly how to use plant nanobiotechnology for improving agricultural production.

Dopant and Compositional Modulation Triggered Broadband and Tunable Near-Infrared Emission in Cs2Ag1–xNaxInCl6:Cr3+ Nanocrystals

Abstract: Lead-free halide perovskite nanocrystals (NCs) have attracted more attention and demonstrated versatile potential in optoelectronic applications. However, achieving broadband near-infrared (NIR) emission in such materials remains a challenge. Herein, we successfully obtained Cr3+-doped Cs2AgInCl6 NCs via hot-injection synthesis, which exhibits a NIR emission with a large full width at half-maximum of 193 nm. Furthermore, tunable emission from 998 to 958 nm along with an enhanced photoluminescence quantum yield of 19.7% is realized by gradually substituting Ag+ with Na+, and the blue shift luminescence behavior is attributed to a strengthened crystal field around Cr3+. The excellent chemical and moisture stability together with the as-fabricated Cs2NaInCl6:Cr3+ NC film made by screen printing showcases its application potential in high-resolution images and NIR fluorescent signs. This work proves the possibility of realizing tunable broadband NIR emission in lead-free perovskite NCs and provides guidance for expanding their application in the NIR region.

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems.

Abstract: The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.