Chromosome Number, Ploidy Level, and Nuclear DNA Content in 23 Species of Echeveria (Crassulaceae)

Retention of Mutations in Colchicine-Induced Ornamental Succulent Echeveria 'Peerless'

Mutation breeding has produced promising results, with exceptional attributes including pest/disease and environmental tolerance and desirable ornamental traits. Among the tools used in mutation breeding, chemical mutation is the most inexpensive way to develop novel plants. Succulents have gained popularity with high market demand because they require minimal watering and have plastic-like visuals. Ornamental succulents with rare leaf morphologies are costly. An LD₅₀ study was conducted beforehand to determine the survival rates of colchicine-treated Echeveria 'Peerless'. Mutants in the first generation (MV₁) were identified and analyzed. Determining whether mutagenic characteristics are carried to the subsequent generation (MV₂) is a key component in breeding programs. Additional investigation was performed by producing MV₂ plants through vegetative propagation to determine mutagenic retention. For MV₂, mutants exhibited shortened leaves, increased leaf width and thickness, and fewer leaves, which significantly differed from the control, indicating compactness, wider leaf apex, and varying leaf color. To confirm the mutations, stomatal analysis was conducted, wherein there was a decrease in density and an increase in stomatal size. Likewise, chromosome counting and flow cytometry analysis confirmed the induction of polyploidization. Colchicine induction to develop new cultivars with novel phenotypic and cytogenetic characters is suitable for ornamental succulents.

The complete chloroplast genome of Echeveria lilacina Kimnach & Moran 1980 (Saxifragales: Crassulaceae)

Echeveria lilacina Kimnach & Moran 1980 is a succulent plant having ornamental and ecological importance. In this study, the first complete chloroplast genome of Echeveria lilacina, a species belonging to the Crassulaceae family, was characterized from the de novo assembly of Illumina NovaSeq 6000 paired-end sequencing data. The chloroplast genome of E. lilacina is 150,080 bp in length, which includes a large single-copy (LSC) region of 81,741 bp, a small single-copy (SSC) region of 16,747 bp, and a pair of identical inverted repeat regions (IRs) of 25,796 bp each. The genome annotation revealed a total of 138 genes, including 87 protein-coding genes, 41 transfer RNA (tRNA) genes, and 10 ribosomal RNA (rRNA) genes. The phylogenetic analysis with 15 complete chloroplast genome sequences including outgroup showed that E. lilacina formed the closest taxonomical relationship with Graptopetalum amethystinum in the Crassulaceae family.