This article comments on:
Diouf I, Derivot L, Koussevitzky S, Carretero Y, Bitton F, Moreau L, Causse M. 2020. Genetic basis of phenotypic plasticity and genotype×environment interaction in a ...multi-parental tomato population. Journal of Experimental Botany 71, 5365–5376.
Heterosis goes underground Monforte, Antonio J
Journal of experimental botany,
09/2021, Letnik:
72, Številka:
18
Journal Article
Recenzirano
Odprti dostop
This article comments on:
Dafna A, Halperin I, Oren E, Isaacson T, Tzuri G, Meir A, Schaffer AA, Burger J, Tadmor Y, Buckler ES, Gur A. 2021. Underground heterosis for yield improvement in melon. ...Journal of Experimental Botany 72, 6205–6218.
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.
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 Proteins and TONNEAU1 Recruiting Motif proteins regulate cell division patterns in ovary development to alter final fruit shape. The physical interactions between the members of these two families are necessary for dynamic relocalization of the protein complexes to different cellular compartments when expressed in tobacco leaf cells. Together with data from other domesticated crops and model plant species, the protein interaction studies provide possible mechanistic insights into the regulation of morphological variation in plants and a framework that may apply to organ growth in all plant species.
Melon is an economically important fruit crop that has been cultivated for thousands of years; however, the genetic basis and history of its domestication still remain largely unknown. Here we report ...a comprehensive map of the genomic variation in melon derived from the resequencing of 1,175 accessions, which represent the global diversity of the species. Our results suggest that three independent domestication events occurred in melon, two in India and one in Africa. We detected two independent sets of domestication sweeps, resulting in diverse characteristics of the two subspecies melo and agrestis during melon breeding. Genome-wide association studies for 16 agronomic traits identified 208 loci significantly associated with fruit mass, quality and morphological characters. This study sheds light on the domestication history of melon and provides a valuable resource for genomics-assisted breeding of this important crop.
Premise of the Study
The domestication history of melon is still unclear. An African or Asian origin has been suggested, but its closest wild relative was recently revealed to be an Australian ...species. The complicated taxonomic history of melon has resulted in additional confusion, with a high number of misidentified germplasm collections currently used by breeders and in genomics research.
Methods
Using seven DNA regions sequenced for 90% of the genus and the major cultivar groups, we sort out described names and infer evolutionary origins and domestication centers.
Key Results
We found that modern melon cultivars go back to two lineages, which diverged ca. 2 million years ago. One is restricted to Asia (Cucumis melo subsp. melo), and the second, here described as C. melo subsp. meloides, is restricted to Africa. The Asian lineage has given rise to the widely commercialized cultivar groups and their market types, while the African lineage gave rise to cultivars still grown in the Sudanian region. We show that C. trigonus, an overlooked perennial and drought‐tolerant species from India is among the closest living relatives of C. melo.
Conclusions
Melon was domesticated at least twice: in Africa and Asia. The African lineage and the Indian C. trigonus are exciting new resources for breeding of melons tolerant to climate change.
Cucurbita pepo is a member of the Cucurbitaceae family, the second- most important horticultural family in terms of economic importance after Solanaceae. The "summer squash" types, including Zucchini ...and Scallop, rank among the highest-valued vegetables worldwide. There are few genomic tools available for this species.The first Cucurbita transcriptome, along with a large collection of Single Nucleotide Polymorphisms (SNP), was recently generated using massive sequencing. A set of 384 SNP was selected to generate an Illumina GoldenGate assay in order to construct the first SNP-based genetic map of Cucurbita and map quantitative trait loci (QTL).
We herein present the construction of the first SNP-based genetic map of Cucurbita pepo using a population derived from the cross of two varieties with contrasting phenotypes, representing the main cultivar groups of the species' two subspecies: Zucchini (subsp. pepo) × Scallop (subsp. ovifera). The mapping population was genotyped with 384 SNP, a set of selected EST-SNP identified in silico after massive sequencing of the transcriptomes of both parents, using the Illumina GoldenGate platform. The global success rate of the assay was higher than 85%. In total, 304 SNP were mapped, along with 11 SSR from a previous map, giving a map density of 5.56 cM/marker. This map was used to infer syntenic relationships between C. pepo and cucumber and to successfully map QTL that control plant, flowering and fruit traits that are of benefit to squash breeding. The QTL effects were validated in backcross populations.
Our results show that massive sequencing in different genotypes is an excellent tool for SNP discovery, and that the Illumina GoldenGate platform can be successfully applied to constructing genetic maps and performing QTL analysis in Cucurbita. This is the first SNP-based genetic map in the Cucurbita genus and is an invaluable new tool for biological research, especially considering that most of these markers are located in the coding regions of genes involved in different physiological processes. The platform will also be useful for future mapping and diversity studies, and will be essential in order to accelerate the process of breeding new and better-adapted squash varieties.
Summary
Fruit ripening is divided into climacteric and non‐climacteric types depending on the presence or absence of a transient rise in respiration rate and the production of autocatalytic ethylene. ...Melon is ideal for the study of fruit ripening, as both climacteric and non‐climacteric varieties exist. Two introgressions of the non‐climacteric accession PI 161375, encompassed in the QTLs ETHQB3.5 and ETHQV6.3, into the non‐climacteric ‘Piel de Sapo’ background are able to induce climacteric ripening independently. We report that the gene underlying ETHQV6.3 is MELO3C016540 (CmNAC‐NOR), encoding a NAC (NAM, ATAF1,2, CUC2) transcription factor that is closely related to the tomato NOR (non‐ripening) gene. CmNAC‐NOR was functionally validated through the identification of two TILLING lines carrying non‐synonymous mutations in the conserved NAC domain region. In an otherwise highly climacteric genetic background, both mutations provoked a significant delay in the onset of fruit ripening and in the biosynthesis of ethylene. The PI 161375 allele of ETHQV6.3 is similar to that of climacteric lines of the cantalupensis type and, when introgressed into the non‐climacteric ‘Piel de Sapo’, partially restores its climacteric ripening capacity. CmNAC‐NOR is expressed in fruit flesh of both climacteric and non‐climacteric lines, suggesting that the causal mutation may not be acting at the transcriptional level. The use of a comparative genetic approach in a species with both climacteric and non‐climacteric ripening is a powerful strategy to dissect the complex mechanisms regulating the onset of fruit ripening.
Significance Statement
Regulatory mechanisms common to climacteric and non‐climacteric fruit ripening are not fully understood. Melon is a unique model species presenting both climacteric and non‐climacteric types. ETHQV6.3 QTL allele introgressed into a non‐climacteric background partially restores climacteric ripening. We show that ETHQV6.3 is encoded by the NAC‐domain transcription factor MELO3C016540 (CmNAC‐NOR). Mutations in CmNAC‐NOR in a climacteric genetic background delay fruit ripening and biosynthesis of ethylene, confirming its role in this process.
A mapping F2 population from the cross 'Piel de Sapo' × PI124112 was selectively genotyped to study the genetic control of morphological fruit traits by QTL (Quantitative Trait Loci) analysis. Ten ...QTL were identified, five for FL (Fruit Length), two for FD (Fruit Diameter) and three for FS (Fruit Shape). At least one robust QTL per character was found, flqs8.1 (LOD = 16.85, R2 = 34%), fdqs12.1 (LOD = 3.47, R2 = 11%) and fsqs8.1 (LOD = 14.85, R2 = 41%). flqs2.1 and fsqs2.1 cosegregate with gene a (andromonoecious), responsible for flower sex determination and with pleiotropic effects on FS. They display a positive additive effect (a) value, so the PI124112 allele causes an increase in FL and FS, producing more elongated fruits. Conversely, the negative a value for flqs8.1 and fsqs8.1 indicates a decrease in FL and FS, what results in rounder fruits, even if PI124112 produces very elongated melons. This is explained by a significant epistatic interaction between fsqs2.1 and fsqs8.1, where the effects of the alleles at locus a are attenuated by the additive PI124112 allele at fsqs8.1. Roundest fruits are produced by homozygous for PI124112 at fsqs8.1 that do not carry any dominant A allele at locus a (PiPiaa). A significant interaction between fsqs8.1 and fsqs12.1 was also detected, with the alleles at fsqs12.1 producing more elongated fruits. fsqs8.1 seems to be allelic to QTL discovered in other populations where the exotic alleles produce elongated fruits. This model has been validated in assays with backcross lines along 3 years and ultimately obtaining a fsqs8.1-NIL (Near Isogenic Line) in 'Piel de Sapo' background which yields round melons.
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