Natural polyploidy inVanilla planifolia(Orchidaceae)

Abstract

Vanilla planifolia accessions cultivated in Reunion Island display important phenotypic variation, but little genetic diversity is demonstrated by AFLP and SSR markers. This study, based on analyses of flow cytometry data, Feulgen microdensitometry data, chromosome counts, and stomatal length measurements, was performed to determine whether polyploidy could be responsible for some of the intraspecific phenotypic variation observed. Vanilla planifolia exhibited an important variation in somatic chromosome number in root cells, as well as endoreplication as revealed by flow cytometry. Nevertheless, the 2C-values of the 50 accessions studied segregated into three distinct groups averaging 5.03 pg (for most accessions), 7.67 pg (for the 'Stérile' phenotypes), and 10.00 pg (for the 'Grosse Vanille' phenotypes). For the three groups, chromosome numbers varied from 16 to 32, 16 to 38, and 22 to 54 chromosomes per cell, respectively. The stomatal length showed a significant variation from 37.75 microm to 48.25 microm. Given that 2C-values, mean chromosome numbers, and stomatal lengths were positively correlated and that 'Stérile' and 'Grosse Vanille' accessions were indistinguishable from 'Classique' accessions using molecular markers, the occurrence of recent autotriploid and autotetraploid types in Reunion Island is supported. This is the first report showing evidence of a recent autopolyploidy in V. planifolia contributing to the phenotypic variation observed in this species.

Genome size variation in Orchidaceae subfamily Apostasioideae: filling the phylogenetic gap

“…(3) What is the AT/GC composition of apostasioid genomes? (4) Does somatic tissue of Apostasioideae undergo conventional endopolyploidization or progressively partial endoreplication, as previously observed in some other orchids (Bory et al ., ; Trávníček et al ., )?…”

Chromosome Numbers and Stomatal Cell Length in Taraxacum Sect. Palustria From Poland

“…Palustria not found in Poland) to see whether this feature can be helpful in determining ploidy level. The size of stomatal guard cells, a nucleotypic character influenced by nuclear DNA amount (Bory et al, 2008;Hodgson et al, 2010), is correlated with ploidy level in a range of natural and commercial cytotypes/varieties of different plant species (Speckman et al, 1965;Przywara et al, 1988;Cohen and Yao, 1996;Mishra, 1997;Joachimiak and Grabowska-Joachimiak, 2000). Chromosome counting is time-consuming and not suited for routine screening of ploidy level in Taraxacum microspecies.…”

Orchidstra 2.0—A Transcriptomics Resource for the Orchid Family

“…Vanilla planifolia, an epiphytic orchid, is the major natural source of vanilla flavor. The diploid (2n = 2x = 32) V. planifolia has a relatively large genome with a mean diploid nuclear DNA content of 5.03 pg/2C (Bory et al 2008). The transcriptome of V. planifolia has been published (Rao et al 2014), and the raw data were downloaded from the NCBI SRA database and then processed by our bioinformatics pipeline.…”