Induction and Characterization of Tetraploids In Nandina

Nandina (Nandina domestica), a popular plant in the landscape, has escaped cultivation in the southeastern United States and Hawaii. As prolific seed production is the primary determinant of nandina's invasive potential, reducing seed production would lessen, or even eliminate, the invasiveness of this plant. The most widely used genetic approach to reducing plant seed production has been ploidy manipulation. The objective of this project was to induce tetraploids in nandina and to assess their morphological and fertility changes relative to diploids. Two chemicals were used to treat three types of nandina plant materials for tetraploid induction. None of the treatments with oryzalin applied to in vitro cultured nandina shoots or shoot tips of pot plants produced polyploids. Colchicine, applied to growing shoots or germinating seeds, resulted in chromosome doubling. Strong diplontic selection was observed in colchicine-treated plants and it caused rapid losses of tetraploid cells in shoot tips. Effective treatments have been applying colchicine to germinating seeds. More than a dozen of solid tetraploid plants have been obtained. Compared to diploids, tetraploid nandina plants appear to be shorter and narrower in size, have shorter internodes and thicker stems, and have narrower and smaller leaves. Tetraploids had slightly lower pollen stainability than diploids. The most obvious difference between tetraploids and diploids appears to be in female fertility: with tetraploids having much lower fruit set than diploids.