A chemical genetic roadmap to improved tomato flavor Tieman, Denise; Zhu, Guangtao; Resende, Marcio F. R. ...
Science (American Association for the Advancement of Science),
01/2017, Letnik:
355, Številka:
6323
Journal Article
Recenzirano
Modern commercial tomato varieties are substantially less flavorful than heirloom varieties. To understand and ultimately correct this deficiency, we quantified flavor-associated chemicals in 398 ...modern, heirloom, and wild accessions. A subset of these accessions was evaluated in consumer panels, identifying the chemicals that made the most important contributions to flavor and consumer liking. We found that modern commercial varieties contain significantly lower amounts of many of these important flavor chemicals than older varieties. Whole-genome sequencing and a genome-wide association study permitted identification of genetic loci that affect most of the target flavor chemicals, including sugars, acids, and volatiles. Together, these results provide an understanding of the flavor deficiencies in modern commercial varieties and the information necessary for the recovery of good flavor through molecular breeding.
The involvement of ethylene in fruit ripening is well documented, though knowledge regarding the crosstalk between ethylene and other hormones in ripening is lacking. We discovered that AUXIN ...RESPONSE FACTOR 2A (ARF2A), a recognized auxin signaling component, functions in the control of ripening. ARF2A expression is ripening regulated and reduced in the rin, nor and nr ripening mutants. It is also responsive to exogenous application of ethylene, auxin and abscisic acid (ABA). Over-expressing ARF2A in tomato resulted in blotchy ripening in which certain fruit regions turn red and possess accelerated ripening. ARF2A over-expressing fruit displayed early ethylene emission and ethylene signaling inhibition delayed their ripening phenotype, suggesting ethylene dependency. Both green and red fruit regions showed the induction of ethylene signaling components and master regulators of ripening. Comprehensive hormone profiling revealed that altered ARF2A expression in fruit significantly modified abscisates, cytokinins and salicylic acid while gibberellic acid and auxin metabolites were unaffected. Silencing of ARF2A further validated these observations as reducing ARF2A expression let to retarded fruit ripening, parthenocarpy and a disturbed hormonal profile. Finally, we show that ARF2A both homodimerizes and interacts with the ABA STRESS RIPENING (ASR1) protein, suggesting that ASR1 might be linking ABA and ethylene-dependent ripening. These results revealed that ARF2A interconnects signals of ethylene and additional hormones to co-ordinate the capacity of fruit tissue to initiate the complex ripening process.
The essential oil fraction obtained from the rind of
spp. is rich in chemical compounds of interest for the food and perfume industries, and therefore has been extensively studied during the last ...decades. In this manuscript, we provide a comprehensive review of the volatile composition of this oil fraction and rind extracts for the 10 most studied
species:
(sweet orange),
(mandarin),
(grapefruit),
(pummelo),
(lemon),
(citron),
(lime),
(bitter orange),
(bergamot orange), and
(yuzu). Forty-nine volatile organic compounds have been reported in all 10 species, most of them terpenoid (90%), although about half of the volatile compounds identified in
peel are non-terpenoid. Over 400 volatiles of different chemical nature have been exclusively described in only one of these species and some of them could be useful as species biomarkers. A hierarchical cluster analysis based on volatile composition arranges these
species in three clusters which essentially mirrors those obtained with genetic information. The first cluster is comprised by
and
, and is mainly characterized by the presence of a larger abundance of non-terpenoid ester and aldehyde compounds than in the other species reviewed. The second cluster is comprised by
,
,
, and
, and is characterized by the prevalence of mono- and sesquiterpene hydrocarbons. Finally,
shows a particular volatile profile with some sulfur monoterpenoids and non-terpenoid esters and aldehydes as part of its main differential peculiarities. A systematic description of the rind volatile composition in each of the species is provided together with a general comparison with those in leaves and blossoms. Additionally, the most widely used techniques for the extraction and analysis of volatile
compounds are also described.
expanded tomato fruit volatile landscape Rambla, José L; Tikunov, Yury M; Monforte, Antonio J ...
Journal of experimental botany,
08/2014, Letnik:
65, Številka:
16
Journal Article
Recenzirano
Odprti dostop
A tomato fruit volatile review is presented which addresses updated biosynthesis pathways, control of emission by conjugation and hydrolysis, and discussion about the difficulties in and ...opportunities for breeding better tasting tomatoes.
Summary
Fleshy tomato fruit typically lacks stomata; therefore, a proper cuticle is particularly vital for fruit development and interaction with the surroundings. Here, we characterized the tomato ...SlSHINE3 (SlSHN3) transcription factor to extend our limited knowledge regarding the regulation of cuticle formation in fleshy fruits.
We created SlSHN3 overexpressing and silenced plants, and used them for detailed analysis of cuticular lipid compositions, phenotypic characterization, and the study on the mode of SlSHN3 action.
Heterologous expression of SlSHN3 in Arabidopsis phenocopied overexpression of the Arabidopsis SHNs. Silencing of SlSHN3 results in profound morphological alterations of the fruit epidermis and significant reduction in cuticular lipids. We demonstrated that SlSHN3 activity is mediated by control of genes associated with cutin metabolism and epidermal cell patterning. As with SlSHN3 RNAi lines, mutation in the SlSHN3 target gene, SlCYP86A69, resulted in severe cutin deficiency and altered fruit surface architecture. In vitro activity assays demonstrated that SlCYP86A69 possesses NADPH‐dependent ω‐hydroxylation activity, particularly of C18:1 fatty acid to the 18‐hydroxyoleic acid cutin monomer.
This study provided insights into transcriptional mechanisms mediating fleshy fruit cuticle formation and highlighted the link between cutin metabolism and the process of fruit epidermal cell patterning.
Betalains are tyrosine‐derived red‐violet and yellow pigments, found in plants only of the Caryophyllales order. Although much progress has been made in recent years in the understanding of the ...betalain biosynthetic process, many questions remain open with regards to several of the proposed steps in the pathway. Most conspicuous by its absence is the characterization of the first committed step in the pathway, namely the 3‐hydroxylation of tyrosine to form l‐3,4‐dihydroxyphenylalanine (l‐DOPA). We used transcriptome analysis of the betalain‐producing plants red beet (Beta vulgaris) and four o'clocks (Mirabilis jalapa) to identify a novel, betalain‐related cytochrome P450‐type gene, CYP76AD6, and carried out gene silencing and recombinant expression assays in Nicotiana benthamiana and yeast cells to examine its functionality. l‐DOPA formation in red beet was found to be redundantly catalyzed by CYP76AD6 together with a known betalain‐related enzyme, CYP76AD1, which was previously thought to only catalyze a succeeding step in the pathway. While CYP76AD1 catalyzes both l‐DOPA formation and its subsequent conversion to cyclo‐DOPA, CYP76AD6 uniquely exhibits only tyrosine hydroxylase activity. The new findings enabled us to metabolically engineer entirely red‐pigmented tobacco plants through heterologous expression of three genes taking part in the fully decoded betalain biosynthetic pathway.
Key message
We have established a DNA-free genome editing method via ribonucleoprotein-based CRISPR/Cas9 in cultivated tomato and obtained mutant plants regenerated from transfected protoplasts with ...a high mutation rate.
The application of genome editing as a research and breeding method has provided many possibilities to improve traits in many crops in recent years. In cultivated tomato (
Solanum lycopersicum
), so far only stable
Agrobacterium
-mediated transformation carrying CRISPR/Cas9 reagents has been established. Shoot regeneration from transfected protoplasts is the major bottleneck in the application of DNA-free genome editing via ribonucleoprotein-based CRISPR/Cas9 method in cultivated tomato. In this study, we report the implementation of a transgene-free breeding method for cultivated tomato by CRISPR/Cas9 technology, including the optimization of protoplast isolation and overcoming the obstacle in shoot regeneration from transfected protoplasts. We have identified that the shoot regeneration medium containing 0.1 mg/L IAA and 0.75 mg/L zeatin was the best hormone combination with a regeneration rate of up to 21.3%. We have successfully obtained regenerated plants with a high mutation rate four months after protoplast isolation and transfection. Out of 110 regenerated M
0
plants obtained, 35 (31.8%) were mutated targeting both
SP
and
SP5G
genes simultaneously and the editing efficiency was up to 60% in at least one allele in either
SP
or
SP5G
genes.
Shelf life is an important quality trait for many fruit, including tomatoes. We report that enrichment of anthocyanin, a natural pigment, in tomatoes can significantly extend shelf life. Processes ...late in ripening are suppressed by anthocyanin accumulation, and susceptibility to Botrytis cinerea, one of the most important postharvest pathogens, is reduced in purple tomato fruit. We show that reduced susceptibility to B. cinerea is dependent specifically on the accumulation of anthocyanins, which alter the spreading of the ROS burst during infection. The increased antioxidant capacity of purple fruit likely slows the processes of overripening. Enhancing the levels of natural antioxidants in tomato provides a novel strategy for extending shelf life by genetic engineering or conventional breeding.
Display omitted
•Anthocyanin accumulation doubles the postharvest storage time of tomato fruit•Anthocyanin enrichment reduces susceptibility of tomato fruit to Botrytis cinerea•Longer shelf life is associated with high hydrophilic antioxidant capacity of fruit•Anthocyanins perturb the dynamics of the ROS burst during infection by B. cinerea
Synthetic Biology requires efficient and versatile DNA assembly systems to facilitate the building of new genetic modules/pathways from basic DNA parts in a standardized way. Here we present ...GoldenBraid (GB), a standardized assembly system based on type IIS restriction enzymes that allows the indefinite growth of reusable gene modules made of standardized DNA pieces. The GB system consists of a set of four destination plasmids (pDGBs) designed to incorporate multipartite assemblies made of standard DNA parts and to combine them binarily to build increasingly complex multigene constructs. The relative position of type IIS restriction sites inside pDGB vectors introduces a double loop ("braid") topology in the cloning strategy that allows the indefinite growth of composite parts through the succession of iterative assembling steps, while the overall simplicity of the system is maintained. We propose the use of GoldenBraid as an assembly standard for Plant Synthetic Biology. For this purpose we have GB-adapted a set of binary plasmids for A. tumefaciens-mediated plant transformation. Fast GB-engineering of several multigene T-DNAs, including two alternative modules made of five reusable devices each, and comprising a total of 19 basic parts are also described.
Polyphenol oxidases (PPOs) catalyze the oxidization of polyphenols, which in turn causes the browning of the eggplant berry flesh after cutting. This has a negative impact on fruit quality for both ...industrial transformation and fresh consumption. Ten
genes (named
-
) were identified in eggplant thanks to the recent availability of a high-quality genome sequence. A CRISPR/Cas9-based mutagenesis approach was applied to knock-out three target
genes (
, and
, which showed high transcript levels in the fruit after cutting. An optimized transformation protocol for eggplant cotyledons was used to obtain plants in which Cas9 is directed to a conserved region shared by the three
genes. The successful editing of the
, and
loci of
regenerated plantlets was confirmed by Illumina deep sequencing of amplicons of the target sites. Besides, deep sequencing of amplicons of the potential off-target loci identified
proved the absence of detectable non-specific mutations. The induced mutations were stably inherited in the T
and T
progeny and were associated with a reduced PPO activity and browning of the berry flesh after cutting. Our results provide the first example of the use of the CRISPR/Cas9 system in eggplant for biotechnological applications and open the way to the development of eggplant genotypes with low flesh browning which maintain a high polyphenol content in the berries.
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