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Characteristics in autotetraploid kumquats (Fortunella spp.) induced by colchicine treatment to nucellar embryos and their utilization for triploid breeding

Nukaya, Tsunaki, Sudo, Miki, Yahata, Masaki, Nakajo, Yoshiyuki, Ohta, Tomohiro, Yasuda, Kiichi, Tominaga, Akiyoshi, Mukai, Hiroo, Kunitake, Hisato
Scientia horticulturae 2019 v.245 pp. 210-217
Citrus, Fortunella crassifolia, Fortunella japonica, autotetraploidy, breeding, colchicine, cultivars, diploidy, flowers, horticulture, kumquats, leaf morphology, leaves, pericarp, pollen, seeds, staining, total soluble solids, triploidy
Three Fortunella (kumquat) species, the Meiwa kumquat (F. crassifolia Swingle), the Round kumquat [F. japonica (Thunb.) Swingle] and the Changshou kumquat (F. obovata hort. ex Tanaka), showing tetraploid, which had been induced by treating the seeds with colchicine, were examined for origin and horticultural characteristics (e. g. morphology of leaves, flowers, pollen and fruits). Additionally, these tetraploid kumquats were crossed to produce triploid kumquats. All of the tetraploids were confirmed to be derived from the nucellar embryo of each original kumquat by examining their chromosomal composition with chromomycin A3 staining. All of the tetraploid kumquats had the typical morphological characteristics of tetraploid Citrus plants, such as round and thick leaves, and large flowers and pollen grains. On the other hand, the fruits of these tetraploid plants showed desirable traits for kumquats such as thicker pericarp and higher soluble solids content. Furthermore, when these tetraploids were crossed with some diploid cultivars, triploid progenies were obtained from almost all of the cross combinations.