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Renwei Huang, Daofeng Liu, Min Zhao, Zhineng Li, Mingyang Li, and Shunzhao Sui

Lobularia maritima (L.) Desv. is an important ornamental plant. We investigated an efficient method to induce tetraploid plants of L. maritima (L.) Desv. by treating germinating seeds and apical growing points of seedlings with a range of concentrations of colchicine for different periods of time. Examination of the ploidy level by counting chromosome numbers at metaphase confirmed that the chromosome number of diploid plants was 2n = 2x = 24, whereas 2n = 4x = 48 was observed in tetraploid plants. The morphological characteristics of the diploid and colchicine-induced tetraploid plants were compared. Increases in the size of leaves, flowers, and stomata were observed in the tetraploid plants compared with the diploids. However, the stomatal density and plant height of the tetraploid plants were lower than for the diploid plants. This study presents the first report of autotetraploid plants of L. maritima (L.) Desv., and of the successful generation of tetraploid plants with improved ornamental traits by colchicine treatment.

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Rui Li, Lu Fan, Jingdong Lin, Mingyang Li, Daofeng Liu, and Shunzhao Sui

Kalanchoe (Kalanchoe blossfeldiana) is a common potted flower that is popular throughout the world. Brown spot (caused by Stemphylium lycopersici) is one of the common foliage diseases in kalanchoe. This disease tends to infect leaves of kalanchoe plants in hot and humid environments, reducing their aesthetic value. The current investigation aimed to generate mutations resistant to brown spot in ‘Mary’ kalanchoe through chemical mutagenesis followed by molecular marker identification. Putative mutants were developed by treating embryogenic calluses with ethyl methanesulfonate (EMS) at median lethal doses (LD50)–either a 0.8% concentration for 2 hours or a 1.0% concentration for 0.5 hours. Brown spot crude toxin solution was used as the selection agent to identify disease-resistant calluses during tissue culture. The optimal crude concentration (60%) was determined by soaking calluses with different concentrations of crude pathogen: 0%, 20%, 40%, 60%, and 80% (v/v). A total of 32 anti-brown spot lines were regenerated and tested for disease resistance with detached leaves. Three regenerated EMS mutant lines showed no obvious brown spot lesions on their leaves after the disease resistance assay and were subjected to polymorphism identification by start codon targeted (SCoT) molecular markers. Three (SCoT40, SCoT71, and SCoT72) of 45 selected primers were chosen to identify the mutants. This work may lay the foundation for further development of new disease-resistant cultivars of kalanchoe.

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Shunzhao Sui, Jianghui Luo, Daofeng Liu, Jing Ma, Weiting Men, Lu Fan, Yu Bai, and Mingyang Li

Wintersweet (Chimonanthus praecox) is a woody garden plant with fragrant flowers, which blooms in deep winter. The vase life of fresh cut flowers is 8–9 days. We applied ethylene and 1-methylcyclopropene (1-MCP; an ethylene action inhibitor) to test the role of ethylene in flower opening and senescence. In addition, abscisic acid (ABA), gibberellic acid (GA3), two cytokinins, 6-benzylaminopurine (6-BA), and zeatin (ZT) were also applied. The expression pattern of CpSRG1, a senescence-related gene, was analyzed. Ethylene treatment accelerated flower opening and senescence, decreasing vase life by 2.1 days. It also decreased flower break strength, indicating the induction of abscission. 1-MCP slowed opening, delayed senescence, and prolonged vase life by 2.6 days. Ethylene dramatically induced the expression of the CpSRG1 gene, while 1-MCP suppressed it. ZT promoted flower opening and increased vase life by 1.6 days. It suppressed the expression of CpSRG1. 6-BA, GA3, or ABA had no significant effect on flower opening and senescence of wintersweet.

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Daofeng Liu, Jing Ma, Jianfeng Yang, Tien V. Nguyen, Huamin Liu, Renwei Huang, Shunzhao Sui, and Mingyang Li

Wintersweet is a woody ornamental plant and has a long history of human cultivation. Few molecular markers have been characterized and remain scant in wintersweet. This study aimed to mine simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs) from the transcriptomic database of wintersweet. A total of 3972 SSRs and 97,060 putative SNPs/indels (92,307 SNPs and 4753 indels) were identified in this data set. This study marks the highest number of SSR and SNP markers discovered to date from wintersweet by using transcriptome sequencing data. These identified markers will provide a useful source for molecular genetic studies such as genetic diversity and characterization, association mapping, and map-based gene cloning in wintersweet.

Open access

Huan Hu, Nan Chai, Haoxiang Zhu, Rui Li, Renwei Huang, Xia Wang, Daofeng Liu, Mingyang Li, Xingrong Song, and Shunzhao Sui

Wintersweet (Chimonanthus praecox) is one of the most popular winter-blooming species. Effective vegetative propagation is necessary for commercial usage and protection of wintersweet. In the current study, the four factors, namely hormone type (A), hormone concentration (B), soaking duration (C), and medium (D), were assessed using an L16 (44) orthogonal test design. The hormone types include ABT (A1), α-naphthalene acetic acid (NAA) (A2), indole butyric acid (IBA) (A3), and indole-3-acetic acid (IAA) (A4); the hormone concentrations include 100 mg·L−1 (B1), 500 mg·L−1 (B2), 1000 mg·L−1 (B3), and 1500 mg·L−1 (B4); the soaking durations include 5 seconds (C1), 5 minutes (C2), 30 minutes (C3), and 3 hours (C4); and the mediums include perlite: peat in the ratios 1:0 (D1), 2:1 (D2), 1:1 (D3), and 1:2 (D4). The results showed that hormone and proper medium could significantly improve the cutting survival, rooting, and sprouting, whereas poor factor combinations, especially high hormone concentrations combined with long soaking durations may be threatened to the cuttings and rooting. In actual experiments, we successfully obtained an excellent rooting percentage (62.22%) of wintersweet from treatment No. 5 (A2B1C2D3), which is perlite and peat (1:1) as the medium and soaking the cuttings in 100 mg·L−1 NAA for 5 minutes as the hormone treatment. This combination can already meet the requirements for commercial production. A range analysis showed that the medium and hormone concentration were the most important factors affecting the cutting of wintersweet. An analysis of variance also showed that the medium and hormone concentration can significantly or extremely significantly affect most cutting indicators. Moreover, our results revealed that an orthogonal design method is an effective tool for establishing an improved technique for cutting propagation.