Optimizing germplasm characterization via phenotypic diversity assessment and descriptor selection in Passiflora spp.
摘要
Quantifying the genetic variability and diversity of Passiflora spp. species is essential to determine their fruit, ornamental and medicinal value. The objective of this study was to evaluate the phenotypic diversity of 114 spp. genotypes based on 74 morphological descriptors related to the leaves, flowers and whole plant, as well as to eliminate redundancy through a list of minimum descriptors for characterization of the germplasm. For this purpose, we submitted 18 quantitative (morphometric) traits to principal component analysis, discarding the traits with low contribution (≤ 6.0%) to the first two components (PC1 and PC2), but which presented correlation above 0.70. The 56 qualitative (multicategorical) descriptors were analyzed according to Shannon's entropy. The analysis was performed using the Gower distance and clustering by UPGMA (Unweighted Pair Group Method Using Arithmetic Averages). After selecting the most informative descriptors, we used nonparametric analysis (random forest - RF) to identify the most important variables within each group formed, as well as the reliability of the clustering. Based on the results obtained, it was possible to identify and discard 29 (51.79%) qualitative descriptors and seven quantitative ones (38.89%). The joint analyses with and without discarding the qualitative and quantitative descriptors led to similar clusters, especially among genotypes of the same species. The RF analysis achieved consistently satisfactory results, enabling ranking the predictor variables within the groups formed with a Kappa index of 87% and accuracy of 88%. The information generated can guide future work both in the area of genetic resources and genetic improvement of Passiflora.