Vanilla

2C nuclear DNA content varied from 4.72 (±0.05) pg (V. tahitensis) to 12.00 (±0.11) pg (V. phalaenopsis Reichb. f. ex Van Houtte) for 34 wild accessions. One accession CR0067 (Vanilla sp.) had an extreme value at 22.31 pg (one measure with wheat standard) (Table 2.1), which was confirmed by using another standard (pea, data not shown). Intra-accession variation coefficients did not exceed 5%.

These results indicate that genome size variations exist in Vanilla, which could suggest the occurrence of polyploid species, based on what was detected for V. planifolia (Bory et al., 2008a). In particular, African accessions displayed bigger genome sizes than American accessions, with 2C DNA content ranging from 6.93 to 22.31 pg and 4.72 to 9.23 pg, respectively. African species may, therefore, have been subjected to more dramatic genomic rearrangements and polyploidization events than their American or Asian counterparts. Finally, as it was observed in V. planifolia in Reunion Island (Bory et al., 2008a), intraspecific genome size variations were revealed in some species (V. imperialis Kraenzl., V. albida Blume), which may reflect the occurrence of different ploidy levels even within species. These results need to be explored further by chromosome counts for each species, but they already strongly suggest that polyploidy might be a major phenomenon in the evolution of Vanilla.

TABLE 2.1 Accession Code from the Vanilla Genetic Resources Collection of CIRAD Reunion Island Accession Code

Accession				Mean 2C pg (±s.d.)
Code	Species	Origina	Place of Sampling
Group Ab	V. planifolia “Classique”	America	Reunion Island	5.03 (±0.16)
Group Bb	V. planifolia “Stérile”	America	Reunion Island	7.67 (±0.14)
Group Cb	V. planifolia “Grosse Vanille”	America	Reunion Island 10.00	(±0.28)
CR0056	V. planifolia × V. phaeantha	N/A	Artificial hybrid	4.48 (±0.10)
CR0747	V. planifolia × V. planifolia	N/A	Artificial hybrid	5.24 (±0.12)
CR0003	V. planifolia × V. tahitensis	N/A	Artificial hybrid	10.12 (±0.10)
CR0062	V. bahiana	America	Unknown	6.70 (±0.32)
CR0072	V. bahiana	America	Brazil (Bahia)	6.60
CR0076	V. bahiana	America	Brazil (Bahia)	6.52
CR0085	V. bahiana	America	Brazil (Bahia)	7.28
CR0097	V. bahiana	America	Brazil (Bahia)	7.09
CR0099	V. bahiana	America	Brazil (Bahia)	6.91
CR0666	V. chamissonis	America	Brazil (Sao Paulo)	8.22 (±0.06)
CR0667	V. chamissonis	America	Brazil (Sao Paulo)	8.14 (±0.35)
CR0702	V. chamissonis	America	Unknown	7.47 (±0.03)
CR0693	V. (cf.) grandiflora Lindl.	America	Guyana	9.23 (±0.25)
CR0109	V. leprieuri R. Porteres	America	French Guyana	7.74 (±0.02)
CR0686	V. odorata	America	Unknown	4.95 (±0.12)
CR0083	V. palmarum	America	Brazil (Bahia)	7.00 (±0.29)
CR0017	V. tahitensis	America	French Polynesia	4.72 (±0.05)
CR0063	V. tahitensis	America	Unknown	6.88 (±0.13)
CR0069	V. trigonocarpa Hoehne	America Brazil (Alagoinhas)	8.21 (±0.07)
CR0103	V. africana Lindl.	Africa	Africa	10.25 (±0.06)
CR0107	V. africana	Africa	Africa	10.22 (±0.18)
CR0696	V. crenulata Rolfe	Africa	Unknown	9.88 (±0.34)
CR0091	V. crenulata	Africa Africa	10.24 (±0.16)
CR0102	V. crenulata	Africa	Africa	9.79 (±0.37)
CR0106	V. crenulata	Africa	Africa	10.47 (±0.38)
CR0108	V. humblotii Rchb. f.	Africa	Comoros	11.81 (±0.09)
CR0104	V. imperialis Kraenzl.	Africa	Africa	6.93
CR0105	V. imperialis	Africa	Africa	10.14 (±0.34)
CR0796	V. imperialis	Africa	Unknown	7.18 (±0.00)
CR0797	V. imperialis	Africa	Unknown	7.06 (±0.24)
CR0141	V. madagascariensis	Africa	Madagascar	8.06
CR0142	V. madagascariensis	Africa	Madagascar	8.02
CR0146	V. phalaenopsis	Africa	Unknown	12.00 (±0.11)
CR0067	Vanilla sp.	Africa	Central Africa	22.31
CR0058	V. albida	Asia	Unknown	5.90 (±0.16)
CR0793	V. albida	Asia	Thailand	5.15
CR0059	V. albida	Asia	Unknown	8.65 (±0.08)
CR0145	V. aphylla	Asia	Thailand	9.81 (±0.03)