The fragrant orchid <i>Vanilla chamissonis</i>: an appraisal of the genetic structure of wild populations from Osununú Natural Reserve (Misiones, Argentina)

Abstract

Due to diverse factors the commercial crops of vanilla are highly vulnerable to genetic erosion. The species Vanilla chamissonis Klotzsch has been shown to produce interesting bioeconomic compounds that could diversify the market. In Argentina, the distribution of this fragrant orchid is restricted to specific north-eastern regions, like the Osununú Natural Reserve (at San Ignacio, Misiones), where it grows wildly in sectors (nuclei). This germplasm represents a locally adapted endemism, and thus is a valuable resource worth preserving. Herein, the genetic characterization of unexplored V. chamissonis´ germplasm was accomplished; as well, the specimens´ molecular identification was assessed in a phylogenetic context using nuclear and chloroplastidial markers. The genotyping exposed that, at least, four gene pools contribute to the genetic diversity of these plants, and that ca. 81% of total genetic variation is allocated within populations. Present results suggest a predominance of sexual reproduction, that population N1 emerges as a candidate unit worth conserving, and that a genetic discontinuity was evidenced between northeastern and southwestern nuclei due to their different genetic constitutions. In concurrence, a tenuous isolation by distance was also unveiled. Our phylogenetic results suggest that it is appropriate to consider the vanilla germplasm surveyed as V. chamissonis. The basic knowledge generated in this work will aid in guiding the in-situ conservation and management initiative, ongoing at the Osununú´s reserve.