Cultivation of crops in urban environments might reduce the environmental impact of food production
. However, lack of available land in cities and a need for rapid crop cycling, to yield quickly and ...continuously, mean that so far only lettuce and related 'leafy green' vegetables are cultivated in urban farms
. New fruit varieties with architectures and yields suitable for urban farming have proven difficult to breed
. We identified a regulator of tomato stem length (SlER) and devised a trait-stacking strategy to combine mutations for condensed shoots, rapid flowering (SP5G) and precocious growth termination (SP). Application of our strategy using one-step CRISPR-Cas9 genome editing restructured vine-like tomato plants into compact, early yielding plants suitable for urban agriculture. Field data confirmed that yields were maintained, and we demonstrated cultivation in indoor farming systems. Targeting the same stem length regulator alone in groundcherry, another Solanaceae plant, also enabled engineering to a compact stature. Our approach can expand the repertoire of crops for urban agriculture.
Most plant roots have multiple cortex layers that make up the bulk of the organ and play key roles in physiology, such as flood tolerance and symbiosis. However, little is known about the formation ...of cortical layers outside of the highly reduced anatomy of
. Here, we used single-cell RNA sequencing to rapidly generate a cell-resolution map of the maize root, revealing an alternative configuration of the tissue formative transcription factor SHORT-ROOT (SHR) adjacent to an expanded cortex. We show that maize SHR protein is hypermobile, moving at least eight cell layers into the cortex. Higher-order
mutants in both maize and
have reduced numbers of cortical layers, showing that the
pathway controls expansion of cortical tissue to elaborate anatomical complexity.
The Physalis community science project shows how citizen science not just communicates with and engages people in research but also how it can inform and benefit the professional scientists.
Fruit softening is a key component of the irreversible ripening program, contributing to the palatability necessary for frugivore-mediated seed dispersal. The underlying textural changes are complex ...and result from cell wall remodeling and changes in both cell adhesion and turgor. While a number of transcription factors (TFs) that regulate ripening have been identified, these affect most canonical ripening-related physiological processes. Here, we show that a tomato fruit ripening-specific
(
) TF,
, up-regulates a suite of cell wall-associated genes during late maturation and ripening of locule and pericarp tissues.
repression in transgenic fruit impedes softening, while overexpression throughout the plant under the direction of the 35s promoter confers precocious induction of cell wall gene expression and premature softening. Transcript and protein levels of the wall-loosening protein EXPANSIN1 (
) are strongly suppressed in
RNA interference lines, while
is induced in
-overexpressing transgenic leaves and fruit. In contrast to the role of ethylene and previously characterized ripening TFs, which are comprehensive facilitators of ripening phenomena including softening,
participates in a regulatory subcircuit predominant to cell wall dynamics and softening.
The
Physalis
genus of the
Solanaceae
family is home to many edible food crops including tomatillo, goldenberry, and groundcherry. These
Physalis
members have garnered more attention as consumer ...interest in novel fruits and vegetables has increased because of increasing awareness of the health benefits of eating a diverse diet. As a result of this interest, several preliminary studies were conducted of these
Physalis
to evaluate their nutritional and chemical profiles associated with health benefits. Results showed these crops contain many essential minerals and vitamins, notably potassium and immune system supporting Vitamin C, also known for its antioxidant activity. Beyond nutritional properties, these crops also contain a class of steroidal lactones called withanolides, which have been recognized for their antitumor, and antinflammatory properties. In some studies, withanolide extract from
Physalis
species have exhibited cytotoxicity towards cancers cells. Overall, this review focuses on the nutritional and physiochemical properties of tomatillo, goldenberry, and groundcherry and how they relate to human health.
RNA interference (RNAi) technology has been successfully applied in stacking resistance against viruses in numerous crop plants. During RNAi, the production of small interfering RNAs (siRNAs) from ...template double-standard RNA (dsRNA) derived from expression constructs provides an on-switch for triggering homology-based targeting of cognate viral transcripts, hence generating a pre-programmed immunity in transgenic plants prior to virus infection. In the current study, transgenic potato lines (
Solanum tuberosum
cv. Desiree) were generated, expressing fused viral coat protein coding sequences from
Potato virus X
(PVX),
Potato virus Y
(PVY), and
Potato virus S
(PVS) as a 600-bp inverted repeat expressed from a constitutive 35S promoter. The expression cassette (designated
Ec1/p5941
) was designed to generate dsRNAs having a hairpin loop configuration. The transgene insertions were confirmed by glufosinate resistance, gene-specific PCR, and Southern blotting. Regenerated lines were further assayed for resistance to virus inoculation for up to two consecutive crop seasons. Nearly 100% resistance against PVX, PVY, and PVS infection was observed in transgenic lines when compared with untransformed controls, which developed severe viral disease symptoms. These results establish the efficacy of RNAi using the coat protein gene as a potential target for the successful induction of stable antiviral immunity in potatoes.
has many attributes, including small stature and simple growth requirements, that make it attractive as a model species for monocots. Genetic engineering (transformation) methodology is a key ...prerequisite for adoption of plant species as models. Various transformation approaches have been reported for
including tissue culture-based and
by
infection of floral organs referred to as the floral dip method. The tissue culture-based method utilizes
infection of mature seed-derived callus with subsequent recovery of stable transgenic lines. Vectors found to be most effective contain the hygromycin phosphotransferase selectable marker gene driven by either
or
ubiquitin promoters. As for the floral dip method, there are two reports based on
infection of young
inflorescences. Plants were allowed to mature, seeds were collected, and analysis of the progeny verified the presence of transgenes. Each transformation approach, tissue culture-based and floral dip, has advantages and disadvantages depending on the expertise of personnel and resources available. While the tissue culture-based method results in a higher transformation efficiency than floral dip, implementation requires a specific technical skillset that limits availability of experienced personnel to successfully perform transformations. Less technical experience is required for floral dip; however, a lack of high-quality growth chambers or greenhouses that provide the necessary optimum growing conditions would reduce an already low transformation efficiency or would not result in recovery of transgenic lines. An overview of transformation methods reported for
is presented in this review.
SUMMARY
Deep insights into chloroplast biogenesis have been obtained by mutant analysis; however, in C4 plants a relevant mutant collection has only been developed and exploited for maize. Here, we ...report the initial characterization of an ethyl methyl sulfonate‐induced mutant population for the C4 model Setaria viridis. Approximately 1000 M2 families were screened for the segregation of pale‐green seedlings in the M3 generation, and a subset of these was identified to be deficient in post‐transcriptional steps of chloroplast gene expression. Causative mutations were identified for three lines using deep sequencing‐based bulked segregant analysis, and in one case confirmed by transgenic complementation. Using chloroplast RNA‐sequencing and other molecular assays, we describe phenotypes of mutants deficient in PSRP7, a plastid‐specific ribosomal protein, OTP86, an RNA editing factor, and cpPNP, the chloroplast isozyme of polynucleotide phosphorylase. The psrp mutant is globally defective in chloroplast translation, and has varying deficiencies in the accumulation of chloroplast‐encoded proteins. The otp86 mutant, like its Arabidopsis counterpart, is specifically defective in editing of the rps14 mRNA; however, the conditional pale‐green mutant phenotype contrasts with the normal growth of the Arabidopsis mutant. The pnp mutant exhibited multiple defects in 3′ end maturation as well as other qualitative changes in the chloroplast RNA population. Overall, our collection opens the door to global analysis of photosynthesis and early seedling development in an emerging C4 model.
Significance Statement
Deep understanding of photosynthetic mechanisms in C4 plants is relevant to evolutionary, biochemical and applied aspects of plant science. Setaria viridis is an emerging C4 model system, and we present the first study of mutants defective in chloroplast functions required for photosynthesis.
Structural variants (SVs) underlie important crop improvement and domestication traits. However, resolving the extent, diversity, and quantitative impact of SVs has been challenging. We used ...long-read nanopore sequencing to capture 238,490 SVs in 100 diverse tomato lines. This panSV genome, along with 14 new reference assemblies, revealed large-scale intermixing of diverse genotypes, as well as thousands of SVs intersecting genes and cis-regulatory regions. Hundreds of SV-gene pairs exhibit subtle and significant expression changes, which could broadly influence quantitative trait variation. By combining quantitative genetics with genome editing, we show how multiple SVs that changed gene dosage and expression levels modified fruit flavor, size, and production. In the last example, higher order epistasis among four SVs affecting three related transcription factors allowed introduction of an important harvesting trait in modern tomato. Our findings highlight the underexplored role of SVs in genotype-to-phenotype relationships and their widespread importance and utility in crop improvement.
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•Long-read sequencing of 100 tomato genomes uncovered 238,490 structural variants•Transposons underlie many SVs, and SV hotspots revealed large introgressions•SVs associated with genes are predictive of population-scale changes in expression•New genome assemblies resolved complex breeding QTLs caused by SVs
Comprehensive structural variant identification in tomato genomes allows insight into the evolution and domestication of tomato and serves as a resource for phenotype-directed breeding.
Plant productivity depends on inflorescences, flower-bearing shoots that originate from the stem cell populations of shoot meristems. Inflorescence architecture determines flower production, which ...can vary dramatically both between and within species. In tomato plants, formation of multiflowered inflorescences depends on a precisely timed process of meristem maturation mediated by the transcription factor gene TERMINATING FLOWER (TMF), but the underlying mechanism is unknown. We show that TMF protein acts together with homologs of the Arabidopsis BLADE-ON-PETIOLE (BOP) transcriptional cofactors, defined by the conserved BTB (Broad complex, Tramtrack, and Bric-a-brac)/POZ (POX virus and zinc finger) domain. TMF and three tomato BOPs (SlBOPs) interact with themselves and each other, and TMF recruits SlBOPs to the nucleus, suggesting formation of a transcriptional complex. Like TMF, SlBOP gene expression is highest during vegetative and transitional stages of meristem maturation, and CRISPR/Cas9 elimination of SlBOP function causes pleiotropic defects, most notably simplification of inflorescences into single flowers, resembling tmf mutants. Flowering defects are enhanced in higher-order slbop tmf mutants, suggesting that SlBOPs function with additional factors. In support of this, SlBOPs interact with TMF homologs, mutations in which cause phenotypes like slbop mutants. Our findings reveal a new flowering module defined by SlBOP-TMF family interactions that ensures a progressive meristem maturation to promote inflorescence complexity.
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