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  • Author or Editor: Lei Wang x
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Pectins are synthesized and secreted to the cell wall as highly methyl-esterified polymers and demethyl-esterified by pectin methylesterases (PMEs), which are regulated by pectin methylesterase inhibitors (PMEIs). PMEs and PMEIs are involved in pectin degradation during fruit softening; however, the roles of the PME and PMEI gene families during fruit softening remain unclear. Here, 71 PME and 30 PMEI genes were identified in the peach (Prunus persica) genome and shown to be unevenly distributed on all eight chromosomes. The 71 PME genes comprised 36 Type-1 PMEs and 35 Type-2 PMEs. Transcriptome analysis showed that 11 PME and 15 PMEI genes were expressed during fruit ripening in melting flesh (MF) and stony-hard (SH) peaches. Three PME and five PMEI genes were expressed at higher levels in MF than in SH fruit and exhibited softening-associated expression patterns. Upstream regulatory cis elements of these genes related to hormone response, especially naphthaleneacetic acid and ethylene, were investigated. One PME (Prupe.7G192800) and two PMEIs (Prupe.1G114500 and Prupe.2G279800), and their promoters were identified as potential targets for future studies on the biochemical metabolism and regulation of fruit ripening. The comprehensive data generated in this study will improve our understanding of the PME and PMEI gene families in peach. However, further detailed investigation is necessary to elucidate the biochemical function and regulation mechanism of the PME and PMEI genes during peach fruit ripening.

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Abstract

Selected physical and chemical properties of fresh spent mushroom compost were evaluated and compared to the properties of spent mushroom compost which was aged aerobically for 6 weeks. Bulk density, total pore space, total water at saturation, and percentage air space in fresh and aged spent composts were acceptable for plant growth. Both contained very high levels of soluble salts which were readily leachable. Concentrations of metals were acceptable, but concentrations of K, Ca, and Mg could lead to plant nutrient imbalances. Concentrations of NH4-N in fresh spent mushroom compost were high.

Open Access

Big fruit size and nice red pigmentation combined with good flavor should be the major target for red-fleshed kiwifruit (Actinidia spp.) breeding programs. Genetic diversity and plant characteristics were evaluated on a set of kiwifruit accessions with predominantly red flesh to identify the superior individuals for further breeding or study of commercial application. The leading phenotypic characters varied widely among the accessions. Accession R reached average fruit weight ≈100 g, whereas it ranged from 43.15 to 84.71 g for the other accessions. Fruits of L and Q were flatter in shape than the others. The core volume accounted for fruit proportions ranging from 2.33% to 11.42%. ‘Chuhong’, ‘Honghua’, and K exhibited a round fruit apex, whereas most others showed a depressed apex. R, L, and Q had the highest a* values in the inner pericarp and also the most appealing visual coloration. Results revealed significantly higher soluble solid content (SSC), total sugar, and sugar/acid ratio in Q, R, and L. The 12 pairs of simple sequence repeat (SSR) markers were successfully used to characterize the genetic variability and confirm true-to-type identity for four accessions. However, the limited number of markers had no ability to discriminate among the other 11 accessions. Based on additional 28 SSRs, six of the indistinguishable accessions were confirmed to be genetically different, and three seemed to belong to the same clone vine. The results demonstrated that application of SSR data could improve the efficiency of identifying red-fleshed kiwifruit germplasm.

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Preharvest application of Phellodendron bark (Phellodendron chinese Schneid) extract (PBE) on brown rot and postharvest quality of peach [Prunus persica (L.) Batsch var. platycarpa (Decne.) L.H. Bailey] was investigated. PBE at 0.8, 1.6, and 3.2 mg·mL−1 totally inhibited conidial germination, mycelial growth, and sporulation, respectively, of Monilinia fructicola in vitro. Preharvest PBE treatment at 21.0 mg·mL−1 at 0, 30, 60, and 90 days after full bloom controlled brown rot caused by M. fructicola on peach fruit after harvest and reduced disease incidence and lesion diameter by 37% and 61%, respectively, than those of the control 96 h after inoculation in in vivo experiments. The results from field experiments were consistent during a 3-year period. Fruit from PBE-treated trees showed higher activities of defense enzymes, including peroxidase, phenylalanine ammonia-lyase, chitinase, and β-1,3-glucanase, compared with those of the control during storage. PBE also delayed softening and loss of titratable acidity and inhibited flesh browning during storage. Total soluble solid contents were unaffected by treatment. The results indicate that preharvest application of PBE may be an alternative for controlling brown rot of peach fruit.

Free access