Postharvest Properties of Ultra-Late Maturing Peach Cultivars and Their Attributions to Melting Flesh (M) Locus: Re-evaluation of M Locus in Association With Flesh Texture

Abstract

The postharvest properties of two ultra-late maturing peach cultivars, “Tobihaku” (TH) and “Daijumitsuto” (DJ), were investigated. Fruit were harvested at commercial maturity and held at 25°C. TH exhibited the characteristics of normal melting flesh (MF) peach, including rapid fruit softening associated with appropriate level of endogenous ethylene production In contrast, DJ did not soften at all during 3 weeks experimental period even though considerable ethylene production was observed. Fruit of TH and DJ were treated with 5,000 ppm of propylene, an ethylene analog, continuously for 7 days. TH softened rapidly whereas DJ maintained high flesh firmness in spite of an increase in endogenous ethylene production, suggesting that DJ but not TH lacked the ability to be softened in response to endogenous and exogenous ethylene/propylene. DNA-seq analysis showed that tandem endo-polygalacturonase (endoPG) genes located at melting flesh (M) locus, Pp-endoPGM (PGM), and Pp-endoPGF (PGF), were deleted in DJ. The endoPG genes at M locus are known to control flesh texture of peach fruit, and it was suggested that the non-softening property of DJ is due to the lack of endoPG genes. On the other hand, TH possessed an unidentified M haplotype that is involved in determination of MF phenotype. Structural identification of the unknown M haplotype, designated as M0, through comparison with previously reported M haplotypes revealed distinct differences between PGM on M0 haplotype (PGM-M0) and PGM on other haplotypes (PGM-M1). Peach M haplotypes were classified into four main haplotypes: M0 with PGM-M0; M1 with both PGM-M1 and PGF; M2 with PGM-M1; and M3 lacking both PGM and PGF. Re-evaluation of M locus in association with MF/non-melting flesh (NMF) phenotypes in more than 400 accessions by using whole genome shotgun sequencing data on database and/or by PCR genotyping demonstrated that M0 haplotype was the common haplotype in MF accessions, and M0 and M1 haplotypes were dominant over M2 and M3 haplotypes and co-dominantly determined the MF trait. It was also assumed on the basis of structural comparison of M haplotypes among Prunus species that the ancestral haplotype of M0 diverged from those of the other haplotypes before the speciation of Prunus persica.

Reducing Fruit Quality Losses in Peach Fruits and Increasing Profitability during postharvest Storage Using Salicylic Acid and Aspirin

“…The fruit SSC and SSC/acid ratio of peach fruit were increased with advancing the storage period at 25 °C (Nuzzi, et al, 2015, Nakano et al, 2020, Shalan, 2020. In spite of that, Pinto et al (2015) found that the relationship between SSC and maturity indicators of peach fruit did not observe significant differences.…”

“…Peaches less than 53 N firmness at harvest time will continue to ripen after harvest in good quality compared to those over 53 N firmness. While, peaches fruit in which firmness was 0.7 N/mm 2 at harvest, their firmness reduced dramatically to less than 0.2 N/mm 2 by day 7 at 25 °C (Nakano et al, 2020). However, peach fruit with firmness below 27 N are sensitive and able to be damaged during postharvest and handling.…”

Artificial Control of the <i>Prunus</i> Self-incompatibility System Using Antisense Oligonucleotides Against Pollen Genes

“…Taking all of these results into consideration, we conclude that the two seeds were derived from the breakdown of SI in 'Sordum'. Japanese plum-specificity of the SNP genotype was confirmed using genomic sequencing data (Ono et al, 2018;Nakano et al, 2020;Numaguchi et al, 2019). Japanese apricot, apricot, peach, and sweet cherry were homozygous for "G", whereas Japanese plum was homozygous for "A" (data not shown).…”

“…The first PCR analysis was conducted to exclude the possibility of interspecific hybridization with pollen from other Prunus species in the orchard where the experimental pollinations were conducted, as pollen grains from many Prunus species can readily grow in the pistils of Japanese plum (Morimoto et al, 2019). A Japanese plum-specific single nucleotide polymorphism (SNP) was identified in the early shoot regeneration (ESR) gene on chromosome 1 (data not shown) by mapping genomic DNA sequencing reads from four Japanese plum, 113 Japanese apricot, seven apricot (Numaguchi et al, 2019), three peach (Nakano et al, 2020), and seven sweet cherry cultivars (Ono et al, 2018). The Japanese plum-specificity of the SNP was further confirmed by sequencing the ESR gene of three Japanese plum, one Japanese apricot, one apricot, and two peach cultivars, and 'Stanley', the only European plum planted in the same orchard as described below.…”

“…(A) The position of the Japanese plum-specific SNP on the ESR gene is shown at the top. Sanger sequencing was performed to type the SNP genotype of the five individuals obtained by self-pollination of 'Sordum' in 2021 and eight Prunus cultivars.Japanese plum-specificity of the SNP genotype was confirmed using genomic sequencing data(Ono et al, 2018;Nakano et al, 2020;Numaguchi et al, 2019). Japanese apricot, apricot, peach, and sweet cherry were homozygous for "G", whereas Japanese plum was homozygous for "A" (data not shown).…”