Molecular and microclimatic characterization of two plantations of Vanilla planifolia (Jacks ex Andrews) with divergent backgrounds of premature fruit abortion

- We selected two plantations of V. planifolia with a divergent background of Premature Fruit Abortion.
- Relationship between genetic diversity, microclimatic conditions and Premature Fruit Abortion on V. planifolia was studied.
- Was detected a greater genetic diversity in the plantation does not have background of Premature Fruit Abortion.
- Low levels of heterozygocity detected indicate evidence of high risk of inbreeding depression and reduction in its adaptive capacity under environmental stress.
- Higher ambient temperatures trigger the Premature Fruit Abortion.

In order to elucidate the influence of genetic diversity and microclimatic conditions on Premature Fruit Abortion (PFA) in this study was performed the molecular and microclimatic characterization of two V. planifolia plantations with divergent backgrounds of PFA. The genetic diversity was investigated using microsatellite markers (SSR) and intergenic simple sequence repeats (ISSR) markers. The SSR markers were highly monomorphic and therefore were used only as a reference point to indicate the level of heterozygosity from codominant markers. In contrast, the level of resolution of the ISSR markers in this study was sufficient to distinguish individual differences between the plantations. Overall, the entire analysis performed in this study with ISSR markers pointed to a higher genetic diversity in the El Palmar plantation, which interestingly, does not show evidence of PFA. In this regard, the number of private loci, Shannon's diversity index and the expected heterozygosity estimates were higher for El Palmar than for Calle Grande. These results are consistent with the information generated by the AMOVA and UPGMA analysis. In addition, the low levels of heterozygocity detected with both markers suggest the likelihood that the V. planifolia are showing a reduction in their adaptive capacity due to inbreeding depression processes. Moreover, the records of environmental conditions in recent years showed that during the periods when the PFA had worsened, the environmental temperatures reached up to 45 °C. Finally, our results of correlation analysis pointed out that a low genetic diversity and high environmental temperatures were significantly associated with PFA.