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Alternatives to sulfur dioxide to maintain quality of table grapes, including various combinations of rachis removal, chlorinated wash, hot water treatment, and modified atmosphere packaging, were explored in this study. Grapes were prepared by cutting off the rachis 1 to 2 mm from the fruit or by keeping the clusters intact. After initial preparation, short-stem and cluster grapes were subjected to chlorinated wash and/or hot water (45 °C, 8 min) treatment and packaged in plastic trays sealed with a gas-permeable film. The treated grapes as well as the commercially packed grapes (COM) in their original packages were stored at 5 °C for up to 4 weeks. Hot water treatment resulted in significantly (P < 0.05) higher oxygen retention and lower carbon dioxide accumulation in package headspaces, maintained a firmer texture, higher overall visual quality, lower decay rate, and lower microbial populations than other treatments or COM during the entire storage period. Grapes that were cut from the rachis and treated with hot water and chlorine maintained the highest quality for 4 weeks with the least decay among all treatments. A chlorine prewash treatment significantly (P < 0.05) reduced microbial populations on cluster grapes and maintained better overall quality. Conventional COM grapes developed dark decay and lost turgidity and were of unacceptable quality at 28 days of storage.
Low-temperature storage in darkness is usually used for preserving seedlings for a short period. To investigate whether grafted watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] seedlings are superior to non-grafted ones under low-temperature storage in darkness and to study their physiological differences during storage, watermelon (‘Zaojia 84-24’) scions were grafted to pumpkin (Cucurbita moschata Duch. ‘Zhuangshi’) rootstocks. Carbohydrate levels; chlorophyll and malondialdehyde contents; the activities of superoxide dismutase, catalase, and peroxidase; and photochemical efficiency were assayed during 6 days of storage at 15 °C in darkness. After that, seedlings were transplanted into an artificial climate chamber. The net photosynthetic rate and stomatal conductance (g S) were measured on the first and third days after transplanting. The results showed that the grafted watermelon seedlings had more soluble sugar and chlorophyll contents, higher activities of antioxidant enzymes, and less malondialdehyde content than the non-grafted ones after 6 days of storage. In addition, low-temperature storage in darkness damaged the photosystem II of non-grafted watermelon seedlings more than that of grafted ones. After transplanting, grafted seedlings had a higher net photosynthetic rate. The results suggest that grafted watermelon seedlings were more suitable for the low-temperature storage in darkness than the non-grafted ones.
Peach (Prunus persica) is an important fruit crop worldwide with several thousand cultivars. Cultivar discrimination and hybrid authentication are often required in peach breeding and can be achieved by applying various molecular markers including simple sequence repeat (SSR). In this study a total of 2146 expressed sequence tag (EST)–SSR loci were detected with the 10,737 EST sequences retrieved from the NCBI. A total of 49 EST-SSR markers, including 24 simple ones with a motif comprising of tri-, tetra-, penta-, hexanucleotides, and 25 compound ones, were selected and then primers were designed. Following conventional polymerase chain reaction (PCR) specificity control and sequence authentication, as well as fluorescence-based PCR product size and stutter band evaluation, 37 EST-SSR markers with correct amplification and without stutter band interference were validated. Among them, 14 were polymorphic in 18 closely related peach accessions, with polymorphism information content (PIC) ranging from 0.0994 to 0.3750. The 18 peach accessions can be distinguished using nine polymorphic markers, with the exception of ‘Shangshandayulu’ and ‘Xipu 1’, both being bud sports from ‘Yulu’. The clustering of the accessions as well as the fingerprint profiles supported the authentication of the hybrids. These EST-SSR markers are useful for peach breeding research.
In natural conditions, it takes more than 3 years to complete the Ananas juvenile phase, and another 2 years for adult vegetative growth of the plantlet from in vitro buds. Ethylene has often been used to shorten the juvenile and vegetative phases to produce earlier flowering. It is important to induce in vitro flowering of Ananas plants to understand the flowering mechanism more completely, which is also related to flower organ differentiation and development as well as the pineapple fruit eye development. In this study, Murashige and Skoog (MS) basal medium was used to select the best combination for adventitious bud induction from the callus of Ananas bracteatus var. tricolor (A. tricolor). Flower induction from the callus was studied using 6-benzyladenine (6-BA) and 1-naphthylacetic acid (NAA) at four different concentrations (0, 1.0, 2.0, and 3.0 mg⋅L–1). Our results showed that when MS was added with 3 mg⋅L–1 6-BA and 2 mg⋅L–1 NAA under 2000 μmol⋅m–2⋅s–1 of light for 16 hours per day at a temperature of 20 °C, the callus of A. tricolor grew quickly, and adventitious buds were induced. After more than four successive subcultures (at day 80), differentiation of flower buds was observed on the aging callus tissue before a complete floral organ developed. This research could be used for the flowering regulation of Ananas plants in the future. Inducing flowers directly from the callus has important scientific significance for the differentiation and morphogenesis of Ananas plants.