Cytological Study of <i>Begonia</i> Sections <i>Petermannia</i> and <i>Haagea</i> (Begoniaceae): Chromosome Evolution for 2<i>n</i>=30

Abstract

Previous chromosome information is restricted to nine species in the Asian Begonia sect. Petermannia. We present here the first chromosome counts for 15 taxa and the first karyotype analyses for 14 taxa in sect. Petermannia in addition with a species in sect. Haagea. Among ca. 460 species in sect. Petermannia, chromosome numbers of 24 taxa are available together with the present and previous reports. Among 24 taxa, they show diverse chromosome numbers with 2n= 24-28, 28, 30, 36, and 44. Among 12 taxa with 2n=30 analyzed, two species show the new karyotype for 2n=30=16m+14sm(st) 2sm in Asian Begonia in addition to 2n=30=8m+22sm(st) 2sm of nine species and 2n=30=12m+18sm(st) 2sm of one natural hybrid. We discussed the chromosome evolution for 2n=30 in Asian Begonia among sections Petermannia and Haagea in this study, and sections Baryandra, Coelocentrum, and Diploclinium reported earlier.

Cytological study of <i>Begonia</i> sect. <i>Platycentrum</i> (Begoniaceae) with chromosome numbers 2<i>n</i>=24, 26, and 52

“…Platycentrum have 10 m-chromosomes and two smchromosomes in common. Consequently, our studies of Asian Begonia cytology show that all chromosome variants (ranging from 2n=12 to 44) within 10 sections [i.e., Baryandra (Kono et al 2021a), Coelocentrum (Kono et al 2020), Diploclinium (Kono et al 2021b), Flocciferae (Kono et al 2023a), Haagea (Kono et al 2022a), Jackia (Kono et al 2023b), Parvibegonia (Kono et al 2023a), Petermannia (Kono et al 2022a), Platycentrum (Kono et al 2022b, c), and Reichenheimia (Kono et al 2023b)], consistently have two or four sm-chromosomes within their respective chromosome complements in common.…”

Cytological Study of <i>Begonia</i> Sections <i>Flocciferae</i>, <i>Parvibegonia</i> and <i>Platycentrum</i> (Begoniaceae) with Chromosome Numbers 2<i>n</i>=28 and 56

“…4c) could have originated from 2n=30= 16m+ 14sm(st) 2sm (e.g., B. dipetala Graham of sect. Haagea; Kono et al 2022a) by chromosome fusion of the four mchromosomes (stripe chromosomes, Nos. 5-6 in Fig.…”

Cytological Study of <i>Begonia</i> Sections <i>Jackia</i>, <i>Platycentrum</i> and <i>Reichenheimia</i> (Begoniaceae) with Chromosome Numbers 2<i>n</i>=34 and 38

“…Petermannia (Klotzsch) A.DC. (Kono et al 2022a). Kono et al (2021b) concluded that the chromosomal diversity in Asian Begonia likely originated from chromosome fusion and polyploidization.…”

“…Accordingly, karyotypes of 2n=38 could be characterized by having two longer m-chromosomes, four sm-chromosomes, and four longest mchromosomes fused of m-and sm(st)-chromosome in the chromosome complement. Concerning chromosome evolution by chromosome fusion, four different ways have been reported in Asian Begonia as follows: First, two m-chromosomes fused and transformed to one sm(st)-chromosome, changing the karyotype and decreasing the chromosome number, i.e., from 2n=36= 20m+ 16sm(st) to 2n=30= 8m+ 22sm(st) 2sm in sections Baryandra (Kono et al 2021a(Kono et al , 2023, Coelocentrum (Kono et al 2020(Kono et al , 2022a and Petermannia (Kono et al 2022a); from 2n=32= 20m+ 12sm(st) to 2n=30= 16m+ 14sm(st) 2sm in sect. Haagea (Kono et al 2022a); from 2n=32= 20m+ 12sm(st) to 2n=28= 12m+ 16sm(st) 2sm in sections Flocciferae and Parvibegonia (Kono et al 2023); and from 2n=36= 20m+ 16sm(st) 4sm to 2n=34= 16m+ 18sm(st) 4sm in sections Jackia and Platycentrum (the present study).…”