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  • Author or Editor: Ting-ting Liu x
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Cytological features of ‘Aijiaohuang’ chinese cabbage-pak-choi (Brassica campestris ssp. chinensis) Bcajh97-01A/B genic male-sterile AB line were examined to determine phenotypic reasons for male sterility. The sterile line Bcajh97-01A was found to undergo aberrant cytokinesis during male meiosis. Transcriptional profiling of the flower buds of both fertile and sterile plants was performed at the periods preceding meiosis, at the tetrad to uninucleate pollen period, and at the binucleate to mature pollen period. Transcript-derived fragments (TDFs) from corresponding genes that were expressed in flower buds at these three different stages could be divided into nine classes. We sequenced a total of 14 new TDFs that were differentially displayed at particular pollen developmental stages, including eight genes with unknown or hypothetical functions and six genes showing significant homology with known genes. This characterization of the Bcajh97-01A genic male-sterile line allowed the identification of candidate genes underlying genic male sterility.

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As a native tree species with a strong adaptability, Platycladus orientalis is a species of choice for afforestation and landscaping in northern China. However, it develops mostly male cones and few female cones. In addition, its reproductive characteristics are not yet clear, which limits further breeding work. To systematically clarify the reproductive biology characteristic and fertilization mechanism of P. orientalis, the present study comprehensively investigated the process of micro and macro-sporogenesis in male and female cones from bud initiation to fertilization, and seed development. The specific time in each developmental stage, including bud initiation, microsporogenesis, megasporogenesis, and cone and seed development, was determined, and the abortive phenomenon during development was discovered in both male and female cones. In addition, this research showed that the microspore mother cells were dormant in winter at meiosis stage, and the male gametophyte started to develop when dormancy ended. The tapetum developed normally and belonged to the secretory type. The optimal treatment time for male and female cones transformation by artificial induction was from late June to mid-July. This finding provided a theoretical basis for hybridization, breeding, improvement of seed yield and quality, and artificial induction of male and female cone transformation in P. orientalis.

Open Access

The interaction between potassium (K) and magnesium (Mg) in plants has been intensively studied. However, the responses of different tomato (Solanum lycopersicum L.) cultivars to high K levels at low temperatures remained unclear. Herein, a complete randomized hydroponic experiment was conducted to evaluate the effects of temperature (25 °C day/18 °C night vs. 15 °C day/8 °C night) and K concentrations (156 mg·L−1 vs. 468 mg·L−1) on the growth and Mg nutrition of tomato cultivars Gailiangmaofen (MF) and Jinpeng No. 1 (JP). Compared with the control temperature (25 °C day/18 °C night), the low temperature decreased total biomass, shoot biomass, and Mg uptake in shoot by 17.3%, 24.1%, and 11.8%, respectively; however, the root/shoot ratio was increased. High K had no significant effect on plant growth or biomass compared with the control K concentration (156 mg·L−1); however, Mg concentrations and uptake in shoot were significantly lower under high-K treatment. Significant difference was observed for K uptake, but not for Mg uptake, between the two cultivars. There was no significant interaction between temperature and high K on Mg uptake of tomato, so a combined stress of low temperature and high K further inhibited Mg uptake and transport. Low temperature and high K increased the risk of Mg deficiency in tomato.

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Ethylene response factor (ERF) genes have been involved in responses to biotic and abiotic stress, including hypoxia and anaerobic stress. Vacuum packaging (a typical anaerobic stress) is an effective storage method used to delay browning of fresh-cut lotus root (Nelumbo nucifera). In model plants, ERF genes have been identified as responsive to hypoxia. Whether ERF is associated with browning of vacuum-packaged lotus root has not been studied. The effects of vacuum packaging on browning, phenolic content, the enzyme activity of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), and PPO, PAL, POD, and ERF genes expression in fresh-cut lotus root were studied. Downregulation of NnPAL1, NnPPOA, and NnPOD2/3 attributable to vacuum packaging coincided with increased related enzyme activities and the degree of browning of fresh-cut lotus root. The expression patterns of NnERF4/5 were consistent with the changes in NnPAL1, NnPPOA, and NnPOD2/3 gene expression. It has been proposed that NnERF4/5 could have be important regulators of fresh-cut lotus root browning, and that the relationships of NnERF4/5 and NnPAL1, NnPPOA, and NnPOD2/3 should to be studied further.

Free access

Ethylene response factor (ERF) genes have been characterized in numerous plants, where they are associated with responses to biotic and abiotic stress. Modified atmosphere packaging (MAP) is an effective treatment to prevent lotus root browning. However, the possible relationship between ERF transcription factors and lotus root browning under MAP remains unexplored. In this study, the effects of phenol, phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) enzyme activities; and PPO, PAL, POD, and ERF gene expression on fresh-cut lotus root browning were studied with MAP. The expression pattern of ERF2/5 correlated highly with the degree of browning. It is suggested that NnERF2/5 can be used as an important candidate gene for the regulation of fresh-cut lotus root browning under MAP, and the correlation of each gene should be studied further.

Open Access