Aluminium (Al) toxicity is the most important limiting factor for crop production in acid soil environments worldwide. In some plant species, application of magnesium (Mg(2+)) can alleviate Al toxicity. However, it remains unknown whether overexpression of magnesium transport proteins can improve Al tolerance. Here, the role of AtMGT1, a member of the Arabidopsis magnesium transport family involved in Mg(2+) transport, played in Al tolerance in higher plants was investigated. Expression of 35S::AtMGT1 led to various phenotypic alterations in Nicotiana benthamiana plants. Transgenic plants harbouring 35S::AtMGT1 exhibited tolerance to Mg(2+) deficiency. Element assay showed that the contents of Mg, Mn, and Fe in 35S::AtMGT1 plants increased compared with wild-type plants. Root growth experiment revealed that 100 microM AlCl(3) caused a reduction in root elongation by 47% in transgenic lines, whereas root growth in wild-type plants was inhibited completely. Upon Al treatment, representative transgenic lines also showed a much lower callose deposition, an indicator of increased Al tolerance, than wild-type plants. Taken together, the results have demonstrated that overexpression of ATMGT1 encoding a magnesium transport protein can improve tolerance to Al in higher plants.

The ancient tea plant, as a precious natural resource and source of tea plant genetic diversity, is of great value for studying the evolutionary mechanism, diversification, and domestication of plants. The overall genetic diversity among ancient tea plants and the genetic changes that occurred during natural selection remain poorly understood. Here, we report the genome resequencing of eight different groups consisting of 120 ancient tea plants: six groups from Guizhou Province and two groups from Yunnan Province. Based on the 8,082,370 identified high-quality SNPs, we constructed phylogenetic relationships, assessed population structure, and performed genome-wide association studies (GWAS). Our phylogenetic analysis showed that the 120 ancient tea plants were mainly clustered into three groups and five single branches, which is consistent with the results of principal component analysis (PCA). Ancient tea plants were further divided into seven subpopulations based on genetic structure analysis. Moreover, it was found that the variation in ancient tea plants was not reduced by pressure from the external natural environment or artificial breeding (nonsynonymous/synonymous = 1.05). By integrating GWAS, selection signals, and gene function prediction, four candidate genes were significantly associated with three leaf traits, and two candidate genes were significantly associated with plant type. These candidate genes can be used for further functional characterization and genetic improvement of tea plants.

An in vitro plant regeneration method and an Agrobacterium tumefaciens-mediated genetic transformation protocol were developed for Euonymus alatus. More than 60% of cotyledon and 70% of hypocotyl sections from 10-day-old seedlings of E. alatus produced 2-4 shoots on woody plant medium (WPM) supplemented with 5.0 mg/l 6-benzylaminopurine (BA) plus 0.2 mg/l alpha-naphthalene acetic acid (NAA), and 77% of shoots produced roots on WPM medium with 0.3 mg/l NAA and 0.5 mg/l Indole-3-butyricacid (IBA). On infection with Agrobacterium tumefaciens strain EHA105 harboring a gusplus gene that contained a plant recognizable intron from the castor bean catalase gene to ensure plant-specific beta-glucuronidase (GUS) expression, 16% of cotyledon and 15% of hypocotyl explants produced transgenic shoots using kanamycin as a selection agent, and 67% of these shoots rooted. Stable insertion of T-DNA into the host genome was determined with organ- and tissue-specific expression of the gusplus gene and further confirmed with a PCR-based molecular analysis.

Euonymus alatus (Thunb.) Sieb., commonly known as “burning bush,” is an extremely popular landscape plant in the United States as a result of its brilliant showy red leaves in fall. However, E. alatus is also seriously invasive because of its prolific seed production and effective seed dispersal by birds. Thus, development of sterile, non-invasive, seedless triploid E. alatus is in high demand. In this article, we report successful production of triploid E. alatus using endosperm tissues as explants. In our study, ≈50% of immature endosperm explants and 14% of mature endosperm explants formed compact, green calli after culture in the dark for 8 weeks and then under light for 4 weeks on Murashige and Skoog (MS) medium supplemented with 2.2 μM BA and 2.7 μM α-naphthaleneacetic acid (NAA). Approximately 5.6% of the immature endosperm-derived calli and 13.4% of mature endosperm-derived calli initiated shoots within 8 weeks after they were cultured on MS medium with 4.4 μM benzyladenine (BA) and 0.5 μM indole-3-butyric acid (IBA). Eighty-five percent of shoots rooted after culture on woody plant medium (WPM) containing 4.9 μM IBA for 2 weeks and then on hormone-free WPM medium containing 2.0 g·L−1 activated charcoal for 4 weeks. Eight independently regenerated triploid plants have been identified. Triploid plant regeneration rates observed were 0.42% from immature endosperm explants and 0.34% from mature endosperm explants, respectively, based on the number of endosperm explants cultured. Because triploid plants cannot produce viable seeds, and thus are sterile and non-invasive, some triploid E. alatus plant lines reported here can be used to replace the currently used invasive counterparts. Chemical names used: benzyladenine (BA), indole-3-butyric acid (IBA), and α-naphthaleneacetic acid (NAA).

Tea (Camellia sinensis [L.] O. Kuntze) is an important global economic crop and is considered to enhance health. However, the functions of many genes in tea plants are unknown. Virus-induced gene silencing (VIGS) mediated by tobacco rattle virus (TRV) is an effective tool for the analysis of gene functions, although this method has rarely been reported in tea plants. In this study, we established an effective VIGS-mediated gene knockout technology to understand the functional identification of large-scale genomic sequences in tea plants. The results showed that the VIGS system was verified by detecting the virus and using a real-time quantitative reverse transcription PCR (qRT-PCR) analysis. The reporter gene CsPOR1 (protochlorophyllide oxidoreductase) was silenced using the vacuum infiltration method, and typical photobleaching and albino symptoms were observed in newly sprouted leaves at the whole plant level of tea after infection for 12 d and 25 d. After optimization, the VIGS system was successfully used to silence the tea plant CsTCS1 (caffeine synthase) gene. The results showed that the relative caffeine content was reduced 6.26-fold compared with the control, and the level of expression of CsPOR1 decreased by approximately 3.12-fold in plants in which CsPOR1 was silenced. These results demonstrate that VIGS can be quickly and efficiently used to analyze the function of genes in tea plants. The successful establishment of VIGS could eliminate the need for tissue culture by providing an effective method to study gene function in tea plants and accelerate the process of functional genome research in tea.