Protein gelation is important to obtain desirable sensory and textural structures in foods. Gelation phenomenon requires a driving force to unfold the native protein structure, followed by an aggregation retaining a certain degree of order in the matrix formed by association between protein strands. Protein gelation has been traditionally achieved by heating, but some physical and chemical processes form protein gels in an analogous way to heat-induction. A physical means, besides heat, is high pressure. Chemical means are acidification, enzymatic cross-linking, and use of salts and urea, causing modifications in protein-protein and protein-medium interactions. The characteristics of each gel are different and dependent upon factors like protein concentration, degree of denaturation caused by pH, temperature, ionic strength and=or pressure.

Marker-assisted selection (MAS) in stone fruit (Prunus species) breeding is currently difficult to achieve due to the polygenic nature of the most relevant agronomic traits linked to fruit quality. Genotyping by sequencing (GBS), however, provides a large quantity of useful data suitable for fine mapping using Single Nucleotide Polymorphisms (SNPs) from a reference genome. In this study, GBS was used to genotype 272 seedlings of three F1 Japanese plum (Prunus salicina Lindl) progenies derived from crossing “98–99” (as a common female parent) with “Angeleno,” “September King,” and “September Queen” as male parents. Raw sequences were aligned to the Peach genome v1, and 42,909 filtered SNPs were obtained after sequence alignment. In addition, 153 seedlings from the “98–99” × “Angeleno” cross were used to develop a genetic map for each parent. A total of 981 SNPs were mapped (479 for “98–99” and 502 for “Angeleno”), covering a genetic distance of 688.8 and 647.03 cM, respectively. Fifty five seedlings from this progeny were phenotyped for different fruit quality traits including ripening time, fruit weight, fruit shape, chlorophyll index, skin color, flesh color, over color, firmness, and soluble solids content in the years 2015 and 2016. Linkage-based QTL analysis allowed the identification of genomic regions significantly associated with ripening time (LG4 of both parents and both phenotyping years), fruit skin color (LG3 and LG4 of both parents and both years), chlorophyll degradation index (LG3 of both parents in 2015) and fruit weight (LG7 of both parents in 2016). These results represent a promising situation for GBS in the identification of SNP variants associated to fruit quality traits, potentially applicable in breeding programs through MAS, in a highly heterozygous crop species such as Japanese plum.

Magmatic carbon dioxide (CO2) degassing has been documented before the 31 March 2000 eruption of Usu volcano, Hokkaido, Japan. Six months before the eruption, an increase in CO2 flux was detected on the summit caldera, from 120 (September 1998) to 340 metric tons per day (September 1999), followed by a sudden decrease to 39 metric tons per day in June 2000, 3 months after the eruption. The change in CO2 flux and seismic observations suggests that before the eruption, advective processes controlled gas migration toward the surface. The decrease in flux after the eruption at the summit caldera could be due to a rapid release of CO2 during the eruption from ascending dacitic dikes spreading away from the magma chamber beneath the caldera.

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Nine important fruit quality traits-including fruit weight, stone weight, fruit diameter, skin ground colour, flesh colour, blush colour, firmness, soluble solids content and acidity content-were studied for two consecutive years in two F 1 apricot progeny derived from the crosses 'Bergeron' × 'Currot' (B×C) and 'Goldrich' × 'Currot' (G×C). Results showed great segregation variability between populations, which was expected because of the polygenic nature and quantitative inheritance of all the studied traits. In addition, some correlations were observed among the fruit quality traits studied. QTL (quantitative trait loci) analysis was carried out using the phenotypic data and genetic linkages maps of 'B×C' and 'G×C' obtained with SSR and SNP markers. The most significant QTLs were localised in LG4 for soluble solids content and in LG3 for skin and flesh colour. In LG4, we can highlight the presence of candidate genes involved in D-glucose and D-mannose 33 binding, while in LG3, we identified MYB genes previ-34 ously linked to skin colour by other authors. In order to 35 clearly identify the candidate genes responsible for the 36 analysed traits, we converted the QTLs into expression 37 QTLs and analysed the abundance of transcripts in the 38 segregating genotypes 'GC 2-11' and 'GC 3-7' from 39 the G×C population. Using qPCR, we analysed the gene 40 expression of nine candidate genes associated with the 41 QTLs identified, including transcription factors (MYB 42 10), carotenoid biosynthesis genes (LOX 2, CCD1 and 43 CCD4), anthocyanin biosynthesis genes (ANS, UFGT 44 and F3'5'H), organic acid biosynthesis genes (NAD 45 ME) and ripening date genes (NAC). Results showed 46 variable expression patterns throughout fruit develop-47 ment and between contrasted genotypes, with a correla-48 tion between validated genes and linked QTLs. The 49 MYB10 gene was the best candidate gene for skin col-50 our. In addition, we found that monitoring NAC expres-51 sion is a good RNA marker for evaluating ripening 52 progression.

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