Esther van der Knaap

University of Georgia | UGA · Center for Applied Genetic Technologies, Horticulture

[This corrects the article DOI: 10.1371/journal.pgen.1010751.].

Shape is a primary determinant of consumer preference for many horticultural crops and it is also associated with many aspects of marketing, harvest mechanics, and postharvest handling. Perceptions of quality and preference often map to specific shapes of fruits, tubers, leaves, flowers, roots, and other plant organs. As a result, humans have great...

Crop breeding for mechanized harvesting has driven modern agriculture. In tomato, machine harvesting for industrial processing varieties became the norm in the 1970s. However, fresh-market varieties whose fruits are suitable for mechanical harvesting are difficult to breed because of associated reduction in flavour and nutritional qualities. Here w...

Fleshy fruit shape is an important external quality trait influencing the usage of fruits and consumer preference. Thus, modification of fruit shape becomes one of the major objectives for crop improvement. However, the underlying mechanisms of fruit shape regulation are poorly understood. In this review, we summarize recent progresses in the genet...

Methyl salicylate is an important inter- and intra-plant signaling molecule, but is deemed undesirable by humans when it accumulates to high levels in ripe fruits. Balancing the tradeoff between consumer satisfaction and overall plant health is challenging as the mechanisms regulating volatile levels have not yet been fully elucidated. In this stud...

The mechanisms that regulate the vast diversity of plant organ shapes such as the fruit remain to be fully elucidated. TONNEAU1 Recruiting Motif proteins (TRMs) have been implicated in the control of organ shapes in a number of plant species, including tomato. However, the role of many of them is unknown. TRMs interact with Ovate Family Proteins (O...

Meristem maintenance, achieved through the highly conserved CLAVATA-WUSCHEL (CLV-WUS) regulatory circuit, is fundamental in balancing stem cell proliferation with cellular differentiation. Disruptions to meristem homeostasis can alter meristem size, leading to enlarged organs. Cotton (Gossypium spp.), the world's most important fiber crop, shows in...

Tomato domestication history has been revealed to be a highly complex story. A major contributor to this complexity is an evolutionary intermediate group (Solanum lycopersicum var. cerasiforme; SLC) between the cultivated tomato (Solanum lycopersicum var. lycopersicum; SLL) and its wild relative (Solanum pimpinellifolium; SP). SLC includes accessio...

Blossom-end rot (BER) is a devastating physiological disorder affecting vegetable production worldwide. Extensive research into the physiological aspects of the disorder has demonstrated that the underlying causes of BER are associated with perturbed calcium (Ca ²⁺ ) homeostasis and irregular watering conditions in predominantly cultivated accessio...

Methyl salicylate imparts a potent flavor and aroma described as medicinal and wintergreen that is undesirable in tomato(Solanum lycopersicum) fruit. Plants control the quantities of methyl salicylate through a variety of biosynthetic pathways, including the methylation of salicylic acid to form methyl salicylate and subsequent glycosylation to pre...

Potato OFP20 is associated with the regulation of tuber shape. To further characterise the role of this gene in tuber shape, a panel of 136 potato varieties was re-sequenced to identify variants in the coding region of StOFP20. These SNPs were assembled into haplotypes and their allelic dosage was determined. Haplotype StOFP20.1 is the most common...

Tomato has undergone extensive selections during domestication. Recent progress has shown that genomic structural variants (SVs) have contributed to gene expression dynamics during tomato domestication, resulting in changes of important traits. Here, we performed comprehensive analyses of small RNAs (sRNAs) from nine representative tomato accession...

Human selection on wild populations mostly favored a common set of plant traits during domestication. This process of direct selection also altered other independent traits that were not directly perceived or desired during crop domestication and improvement. A deeper knowledge of the inadvertent and undesirable phenotypic effects and their underly...

Premise: Capsicum annuum (Solanaceae) was originally domesticated in Mexico, where wild (C. annuum var. glabriusculum) and cultivated (C. annuum var. annuum) chile pepper populations (> 60 landraces) are common; additionally wild-resembling individuals (hereafter semiwild) grow spontaneously in anthropogenic environments. Here we analyze the role...

CRISPR/Cas-mediated genome editing is a powerful approach to accelerate yield enhancement to feed growing populations. Most applications focus on “negative regulators” by targeting coding regions and promoters to create nulls or weak loss-of-function alleles. However, many agriculturally important traits are conferred by gain-of-function alleles. T...

A novel haplotype-based approach that uses Procrustes analysis and automatic classification was used to provide further insights into tomato history and domestication. Agrarian societies domesticated species of interest by introducing complex genetic modifications. For tomatoes, two species, one of which had two botanical varieties, are thought to...

Tomato domestication history has been revealed to be a highly complex story. A major contributor to this complexity is an evolutionary intermediate group ( Solanum lycopersicum var. cerasiforme (Alef.) Voss; SLC) between the domesticated tomato ( Solanum lycopersicum var. lycopersicum L.; SLL) and its wild relative ( Solanum pimpinellifolium L.; SP...

Within large-fruited germplasm, fruit size is influenced by flat and globe shapes. Whereas flat fruits are smaller and retain better marketability, globe fruits are larger and more prone to cuticle disorders. Commercial hybrids are often developed from crosses between flat and globe shaped parents because flat shape is thought to be dominant and fr...

Understanding the evolution of deleterious mutations through domestication has fascinated evolutionary biologists and breeders alike. Some domesticated organisms have been reported to accumulate deleterious mutations, i.e. radical amino acid changes, through their domestication history (“cost of domestication”). However, more recent evidence paints...

Key Message Six novel fruit weight QTLs were identified in tomato using multiple bi-parental populations developed from ancestral accessions. Beneficial alleles at these loci arose in semi-domesticated subpopulations and were likely left behind. This study paves the way to introgress these alleles into breeding programs. Abstract The size and weig...

Tomato has undergone extensive selections during domestication. Recent progress has shown that genomic structural variants (SVs) have contributed to gene expression dynamics during tomato domestication, resulting in changes of important traits. Here, through comprehensive analyses of small RNAs (sRNAs) from nine representative tomato accessions, we...

Key message Blossom-End Rot is Quantitatively Inherited and Maps to Four Loci in Tomato . Abstract Blossom-end rot (BER) is a devastating physiological disorder that affects tomato and other vegetables, resulting in significant crop losses. To date, most studies on BER have focused on the environmental factors that affect calcium translocation to...

A novel haplotype-based approach that uses Procrustes analysis and automatic classification was used to provide further insights into tomato history and domestication. Agrarian cultures domesticated species of interest by introducing complex genetic modifications. For tomato, two species, and for one of them two botanical varieties: are thought to...

Fruit flavor is defined as the perception of the food by the olfactory and gustatory systems, and is one of the main determinants of fruit quality. Tomato flavor is largely determined by the balance of sugars, acids and volatile compounds. Several genes controlling the levels of these metabolites in tomato fruit have been cloned, including LIN5, AL...

Trichomes are a common morphological defense against pests, in particular, type IV glandular trichomes have been associated with resistance against different invertebrates. Cultivated tomatoes usually lack or have a very low density of type IV trichomes. Therefore, for sustainable management of this crop, breeding programs could incorporate some na...

Trichomes are a common morphological defense against pests, in particular, type IV glandular trichomes have been associated with resistance against different invertebrates. Cultivated tomatoes usually lack or have a very low density of type IV trichomes. Thus, specific breeding programs to incorporate these natural defences, that are common within...

The size of plant organs such as fruit and seed are crucial yield components. Tomato KLUH underlies the QTL fw3.2 that is an important regulator of fruit and seed weight. However, the mechanism by which the expression levels of KLUH affects organ size is poorly understood. Here, we found that higher expression of SlKLUH increased cell proliferation...

Patterns of indeterminate and determinate growth specify plant architecture and influence crop productivity. In cotton (Gossypium hirsutum), SINGLE FLOWER TRUSS (SFT) stimulates the transition to flowering and determinate growth while its closely related antagonist SELF-PRUNING (SP) maintains meristems in indeterminate states to favor vegetative gr...

Aberrant regulation of metabolic kinases by altered redox homeostasis substantially contributes to aging and various diseases, such as diabetes. We found that the catalytic activity of a conserved family of fructosamine-3-kinases (FN3Ks), which are evolutionarily related to eukaryotic protein kinases, is regulated by redox-sensitive cysteine residu...

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-sca...

A collection of 163 accessions, including Solanum pimpinellifolium, Solanum lycopersicum var. cerasiforme and Solanum lycopersicum var. lycopersicum, was selected to represent the genetic and morphological variability of tomato at its centers of origin and domestication: Andean regions of Peru and Ecuador and Mesoamerica. The collection is enriched...

Directed breeding of horticultural crops is essential for increasing yield, nutritional content, and consumer-valued characteristics such as shape and color of the produce. However, limited genetic diversity restricts the amount of crop improvement that can be achieved through conventional breeding approaches. Natural genetic changes in cis-regulat...

Aberrant regulation of metabolic kinases by altered redox homeostasis is a major contributing factor in aging and disease such as diabetes. However, the biochemical mechanisms by which metabolic kinases are regulated under oxidative stress is poorly understood. In this study, we demonstrate that the catalytic activity of a conserved family of Fruct...

The process of plant domestication is often protracted, involving under-explored intermediate stages with important implications for the evolutionary trajectories of domestication traits. Previously, tomato domestication history has been thought to involve two major transitions: one from wild Solanum pimpinellifolium L. (SP) to a semi-domesticated...

The process of plant domestication is often protracted, involving under-explored intermediate stages with important implications for the evolutionary trajectories of domestication traits. Previously, tomato domestication history has been thought to involve two major transitions: one from wild Solanum pimpinellifolium L. (SP) to a semi-domesticated...

The shape of produce is an important agronomic trait. The knowledge of the cellular regulation of organ shapes can be implemented in the improvement of a variety of crops. The plant-specific Ovate Family Proteins (OFPs) regulate organ shape in Arabidopsis and many crops including rice, tomato, and melon. Although OFPs were previously described as t...

Pepper species (Capsicum spp.) are widely used as food, spice, decoration, and medicine. Despite the recent old-world culinary impact, more than 50 commercially recognized pod types have been recorded worldwide from three taxonomic complexes (A, B, and P). The current study aimed to apply a pan-plastome approach to resolve the plastomic boundaries...

Improving yield by increasing the size of produce is an important selection criterion during the domestication of fruit and vegetable crops. Genes controlling meristem organization and organ formation work in concert to regulate the size of reproductive organs. In tomato, lc and fas control locule number, which often leads to enlarged fruits compar...

Modern tomatoes have narrow genetic diversity limiting their improvement potential. We present a tomato pan-genome constructed using genome sequences of 725 phylogenetically and geographically representative accessions, revealing 4,873 genes absent from the reference genome. Presence/absence variation analyses reveal substantial gene loss and inten...

Elongated tomato fruit shape is the result of the action of the fruit shape genes possibly in coordination with the phytohormone auxin. To investigate the possible link between auxin and the fruit shape genes, a series of auxin (2,4-D) treatments were performed on the wild-type and the fruit shape near-isogenic lines (NILs) in Solanum pimpinellifol...

Host-associated differentiation (HAD) has played a major role in insect diversification at both macroevolutionary and microevolutionary scales. This evolutionary process has been reported in insects associated with wild and domesticated plant species. In particular, domesticated species harbor large genetic and phenotypic diversity associated with...

Plant organ shape is determined by the spatial-temporal expression of genes that control the direction and rate of cell division and expansion, as well as the mechanical constraints provided by the rigid cell walls and surrounding cells. Despite the importance of organ morphology during the plant life cycle, the interplay of patterning genes with t...

Shapes of edible plant organs vary dramatically among and within crop plants. To explain and ultimately employ this variation towards crop improvement, we determined the genetic, molecular and cellular bases of fruit shape diversity in tomato. Through positional cloning, protein interaction studies, and genome editing, we report that OVATE Family P...

Studies of genetic diversity among phenotypically distinct crop landraces improve our understanding of fruit evolution and genome structure under domestication. Chile peppers (Capsicum spp. L.) are economically valuable and culturally important species, and extensive phenotypic variation among landraces exists in southern Mexico, a center of C. ann...

Humans heavily rely on dozens of domesticated plant species that have been further improved through intensive breeding. To evaluate how breeding changed the tomato fruit metabolome, we have generated and analyzed a dataset encompassing genomes, transcriptomes, and metabolomes from hundreds of tomato genotypes. The combined results illustrate how br...

Angiosperms produce seeds as their progeny enclosed in maternally-derived structures called fruits. Evolutionarily, fruits have contributed enormously to the success of the Angiosperms phylum by providing protection and nutrition to the developing seeds, while ensuring the efficient dispersal upon maturity. Fruits vary massively in both size and sh...