Biology subjects

Garcia-Mas, J.

Publications and source records attributed to Garcia-Mas, J..

5 recordsLinked to original sources

bioRxiv2025

A melon (Cucumis melo) homologue of REPRESSOR OF PHOTOSYNTHETIC GENES prevents chloroplast differentiation in the fruit flesh

Fruit flesh color in melon can be orange, green or white, depending on the accumulation of the orange carotenoid {beta}-carotene or / and green chlorophylls. The dominant allele of Green flesh (Gf) causes orange melons, but in the absence of this allele the flesh of ripe melon can be white or green depending on the White flesh (Wf) locus, being white dominant over green. The identity of Wf has remained unclear despite several candidates have been proposed. Here we identified Wf by fine mapping of a segregating population derived from the white-fleshed variety Piel de Sapo (PS, gf gf / Wf Wf) and the orange-fleshed Vedrantais (VED, Gf Gf / wf wf). Wf corresponds to the gene MELO3C003098, herein referred to as CmRPGE1 as it encodes a fruit-specific homologue of REPRESSOR OF PHOTOSYNTHETIC GENES (RPGE) microproteins. Similar to RPGE homologues from other plants, overexpression of the PS allele (CmRPGE1PS) caused a pale green leaf phenotype in Nicotiana benthamiana and Arabidopsis thaliana. By contrast, a 10-nucleotide deletion in the VED allele (CmRPGE1VED) resulted in a loss of RPGE function. The active CmRPGE1PS microprotein interacts with a fruit-localized melon homologue of ARABIDOPSIS PSEUDO-RESPONSE REGULATOR2 (APRR2), a GARP family transcription factor. Binding of CmRPGE1PS retains the melon APRR2 homologue in the cytosol, hence preventing the regulation of target genes involved in chloroplast biogenesis. In green fruit cultivars, the non-functional CmRPGE1VED allele allows APRR2 to perform its function, leading to chloroplast development and consequently a green flesh phenotype. SIGNIFICANT STATEMENTFruit color is a critical quality trait that directly influences consumer preference and market value in melon. In this study, we demonstrate that the White flesh (Wf) gene, a major determinant of melon fruit flesh color, encodes a fruit-specific homologue of REPRESSOR OF PHOTOSYNTHETIC GENES (RPGE) microproteins. The encoded microprotein, CmRPGE1, interacts with melon homologues of ARABIDOPSIS PSEUDO-RESPONSE REGULATOR2 (APRR2), a GARP family transcription factor. In white flesh melons, the CmAPRR2.2 paralog is sequestered in the cytoplasm upon interaction with CmRPGE1, thereby preventing the expression of target genes involved in chlorophyll accumulation. Conversely, the truncated version of CmRPGE1 present in green-fleshed melons fails to interact with CmAPRR2.2 and to prevent its nuclear localization and function, allowing chloroplasts differentiation.

plant biology↗

bioRxiv2022

Knock-out of CmNAC-NOR affects melon climacteric fruit ripening

Fruit ripening is an important process that affects fruit quality. In melon, ETHQV6.3, a QTL involved in climacteric ripening regulation, was previously found to be encoded by CmNAC-NOR, a homologue of the tomato NOR gene. To further investigate CmNAC-NOR function we have obtained two CRISPR/Cas9 mediated mutants (nor-3 and nor-1) in the climacteric Vedrantais background. nor-3, containing a 3-bp deletion altering the NAC domain A, resulted in ~8 days delay of ripening without affecting fruit quality. In contrast, nor-1 contained a 1-bp deletion resulting in a fully disrupted NAC domain, which completely blocked climacteric ripening. nor-1 fruits did not produce ethylene, abscission layer was not formed and there was no external color change. Additionally, volatile components were dramatically altered, seeds were not well developed and flesh firmness was also altered. nor-1 allele in heterozygosis showed ~20 days delay of fruit ripening. Our results provide new information regarding the function of CmNAC-NOR in melon fruit ripening, suggesting that it as a potential target to modulate shelf life in climacteric melon commercial varieties.

plant biology↗

bioRxiv2022

CRISPR/Cas9 gene editing uncovers the role of CTR1 and ROS1 in melon fruit ripening and epigenetic regulation

Melon (Cucumis melo L.) has emerged as an alternative model to study fruit ripening due to the coexistence of climacteric and non-climacteric varieties. The previous characterization of a major QTL ETHQV8.1 sufficient to trigger climacteric ripening in a non-climacteric background allowed the identification within the QTL interval of a negative regulator of ripening CmCTR1-like (MELO3C024518), and a putative DNA demethylase CmROS1 (MELO3C024516), the orthologue of DML2, a DNA demethylase regulating fruit ripening in tomato. To understand the role of these genes in climacteric ripening, we generated homozygous CRISPR knockout mutants of CmCTR1-like and CmROS1 in a climacteric genetic background. The climacteric behavior was altered in both loss-of-function mutants in two summer seasons with an advanced ethylene production profile compared to the climacteric wild type, suggesting a role of both genes in climacteric ripening in melon. Single cytosine methylome analyses of the CmROS1 knockout mutant revealed DNA methylation changes in the promoter regions of key ripening genes as ACS1, ETR1 and ACO1, and ripening associated-transcription factors as NAC-NOR, RIN and CNR, suggesting the importance of CmROS1-mediated DNA demethylation for triggering fruit ripening in melon.

plant biology↗

bioRxiv2019

Transposons played a major role in the diversification between the closely related almond (Prunus dulcis) and peach (P. persica) genomes: Results from the almond genome sequence

Combining both short and long-read sequencing, we have estimated the almond Prunus dulcis cv. Texas genome size in 235 Mbp and assembled 227.6 Mb of its sequence. The highly heterozygous compact genome of Texas comprises eight chromosomes, to which we have anchored over 91% of the assembly. We annotated 27,042 protein-coding genes and 6,800 non-coding transcripts. High levels of genetic variability were characterized after resequencing a collection of ten almond accessions. Phylogenomic comparison with the genomes of 16 other close and distant species allowed estimating that almond and peach diverged around 5.88 Mya. Comparison between peach and almond genomes confirmed the high synteny between these close relatives, but also revealed high numbers of presence-absence variants, many attributable to the movement of transposable elements (TEs). The number and distribution of TEs between peach and almond was similar, but the history of TE movement was distinct, with peach having a larger proportion of recent transpositions and almond preserving a higher level of polymorphism in the older TEs. When focusing on specific genes involved in key characters such as the bitter vs. sweet kernel taste and the formation of a fleshy mesocarp, we found that for one gene associated with the biosynthesis of amygdalin that confers the bitter kernel taste, several TEs were inserted in its vicinity only in sweet almond cultivars but not in bitter cultivars and Prunus bitter kernel relatives, including P. webbii, P. mume, and other species like peach and cherry. TE insertions likely to produce affects in the expression of six more genes involved in the formation of the fleshy mesocarp were also identified. Altogether, our results suggest a key role of TEs in the recent history and diversification of almond with respect to peach.

genomics↗

bioRxiv2017

The fruitENCODE project sheds light on the genetic and epigenetic basis of convergent evolution of climacteric fruit ripening

Fleshy fruit evolved independently multiple times during angiosperm history. Many climacteric fruits utilize the hormone ethylene to regulate ripening. The fruitENCODE project shows there are multiple evolutionary origins of the regulatory circuits that govern climacteric fruit ripening. Eudicot climacteric fruits with recent whole-genome duplications (WGDs) evolved their ripening regulatory systems using the duplicated floral identity genes, while others without WGD utilised carpel senescence genes. The monocot banana uses both leaf senescence and duplicated floral-identity genes, forming two interconnected regulatory circuits. H3K27me3 plays a conserved role in restricting the expression of key ripening regulators and their direct orthologs in both the ancestral dry fruit and non-climacteric fleshy fruit species. Our findings suggest that evolution of climacteric ripening was constrained by limited availability of signalling molecules and genetic and epigenetic materials, and WGD provided new resources for plants to circumvent this limit. Understanding these different ripening mechanisms makes it possible to design tailor-made ripening traits to improve quality, yield and minimize postharvest losses.\n\nOne Sentence SummaryThe fruitENCODE project discovered three evolutionary origins of the regulatory circuits that govern climacteric fruit ripening.

genomics↗