Silverleaf (Chondrostereum purpureum) Effects on Japanese Plum (Prunus salicina)

Silverleaf is an important fungal trunk disease of fruit crops, such as Japanese plum (Prunus salicina). It is known that infection by Chondrostereum purpureum results in discolored wood, “silvered” foliage, and tree decline. However, effects on fruit yield and quality have not been assessed. Therefore, the objectives of this study were to determine C. purpureum pathogenicity on P. salicina and the effects on physiology, fruit yield, and quality, in Chile, in 2019 and 2020. Wood samples from affected plum trees were collected in the Chilean plum productive area. Fungi were isolated by plating wood sections from the necrosis margin on culture media. Morphological and molecular characteristics of the isolates corresponded to C. purpureum (98%). Representative isolates were inoculated from healthy plum plants and after 65-d incubation, wood necrotic lesions and silver leaves were visible. Fungi were reisolated, fulfilling Koch’s postulates. To determine Silverleaf effects, xylem water potential and fruit yield and quality were measured in healthy and Silverleaf-diseased plum trees ‘Angeleno’. Water potential was altered in diseased trees, and fruit yield was reduced by 51% (2019) and by 41% (2020) compared to fruit from healthy trees. Moreover, cover-colour, equatorial-diameter, and weight were reduced, and fruit were softer, failing to meet the criteria to be properly commercialized and exported to demanding markets.

Assembly of the Complete Mitochondrial Genome of Chinese Plum (Prunus salicina): Characterization of Genome Recombination and RNA Editing Sites

Despite the significant progress that has been made in the genome sequencing of Prunus, this area of research has been lacking a systematic description of the mitochondrial genome of this genus for a long time. In this study, we assembled the mitochondrial genome of the Chinese plum (Prunus salicina) using Illumina and Oxford Nanopore sequencing data. The mitochondrial genome size of P. salicina was found to be 508,035 base pair (bp), which is the largest reported in the Rosaceae family to date, and P. salicina was shown to be 63,453 bp longer than sweet cherry (P. avium). The P. salicina mitochondrial genome contained 37 protein-coding genes (PCGs), 3 ribosomal RNA (rRNA) genes, and 16 transfer RNA (tRNA) genes. Two plastid-derived tRNA were identified. We also found two short repeats that captured the nad3 and nad6 genes and resulted in two copies. In addition, nine pairs of repeat sequences were identified as being involved in the mediation of genome recombination. This is crucial for the formation of subgenomic configurations. To characterize RNA editing sites, transcriptome data were used, and we identified 480 RNA editing sites in protein-coding sequences. Among them, the initiation codon of the nad1 gene confirmed that an RNA editing event occurred, and the genomic encoded ACG was edited as AUG in the transcript. Combined with previous reports on the chloroplast genome, our data complemented our understanding of the last part of the organelle genome of plum, which will facilitate our understanding of the evolution of organelle genomes.

Assessing the Effectiveness of Natural Coating Application in Prolonging Shelf-Life in Plumcot Fruits

This study was carried out to assess the morphological characteristics, fruit quality, and antioxidant levels in sucrose ester-coated ‘Harmony’ plumcots (Prunus salicina Lindl. × P. armeniaca L.). Fruit samples in the control group were left untreated, with two further groups undergoing coating either after 0 days of cold storage (0 d CS) or after 7 days of cold storage (7 d CS) to evaluate changes in post-harvest quality at three-day intervals throughout 12 days of room temperature storage (12 DAS). Coating treatment significantly reduced fruit respiration during storage time in the 0 d CS samples, with this being attributed to the clogging of pores in peel stomata and lenticel, as observed on the fruits under scanning electron microscopy; however, the same effect was not observed in the 7 d CS samples from fruits with a high initial CO2 concentration. The coating delayed fruit softening and discoloration during storage in the 0 d CS samples, extending the shelf-life of the fruits for approximately 9 days. However, the coating treatment was found to reduce total flavonoid and anthocyanin content at 6 DAS and 12 DAS in both groups.

Varietal Wealth of Prunus Species

Genus Prunus includes all the stone fruits (peach, nectarine, plum, apricot, almond and cherry) comprise around 98 species and classified under three subgenera namely: Amygdalus (peaches, nectraine and almonds), Prunophora (plums and apricots) and Cerasus (cherries). Genus Prunus have attained a prime position among all the temperate fruit crops as delicious edible drupe, and many species have ornamental values as well. Major species of importance are Prunus persica (peach), Prunus armeniaca (apricot), Prunus salicina (Japanese plum), Prunus domestica (European plum), Prunus americana (American plum), Prunus avium (Sweet cherry), Prunus cerasus (Sour cherry), Prunus dulcis (almond), Prunus ceracifera (Cherry plum), Prunus mira (Behmi), Prunus cerasoides (Wild Himalayan cherry), Prunus mahaleb (Mahaleb cherry) etc. Interspecific hybrids namely: plumcots, pluots and apriums also produce very delicious edible fruits. Commercial cultivars of different stone fruits are J H Hale, Cresthaven, Flordasun, Florda Prince, Elberta, Glohaven, July Elberta, Redhaven, Kanto 5, Sun Haven etc. of peaches, Fantasia, Mayfire, Red Gold, Snow Queen etc. belongs to nectarine, Turkey, Charmagz, Perfection, St. Ambroise, Royal, New Castle etc. are apricots, Santa Rosa, Black Beauty, Kelsey, Green Gage, Methley, Satsuma, Frontier, Burbank etc. are plums, Regina, Burlat, Lapins, Kordia, Stella, Bing, Van, Black Heart, Compact Lambert, Compact Stella etc. are cherries, and California Paper Shell, IXL, Mission, Nonpareil, Drake, Ne Plus Ultra, Pranyaj, Merced etc. are almonds.