Selection of Autotetraploid and its Morphological Characteristics in Meiwa Kumquat (Fortunella crassifolia Swingle)

Abstract

A tetraploid of Meiwa kumquat (Fortunella crassifolia Swingle) was selected from nucellar seedlings using root morphology, and its morphological characteristics were investigated.
One seedling with thick short rootlets was obtained from 457 seedlings. Flow cytometry and chromosome observation demonstrated that the seedling was tetraploid (2n=4X=36). This tetraploid was presumed by Randam Amplified Polymorphic DNA (RAPD) analysis to have derived from nucellar embryos. The tetraploid showed similar morphology to other Citrus tetraploids such as thick, round leaves and larger stomata, flowers, and pollen grains compared with the original diploid. The tetraploid fruit was almost equal in weight and size to that of the diploid, but had a thicker peel and smaller number of developed seeds than the diploid fruit. In the future, the tetraploid obtained in the present study will be important material as a new cultivar and a parent of triploid breeding.