Some of the major impacts of climate change are expected in regions where drought stress is already an issue. Grain legumes are generally drought susceptible. However, tepary bean and its wild relatives within Phaseolus acutifolius or P. parvifolius are from arid areas between Mexico and the United States. Therefore, we hypothesize that these bean accessions have diversity signals indicative of adaptation to drought at key candidate genes such as: Asr2, Dreb2B, and ERECTA. By sequencing alleles of these genes and comparing to estimates of drought tolerance indices from climate data for the collection site of geo-referenced, tepary bean accessions, we determined the genotype x environmental association (GEA) of each gene. Diversity analysis found that cultivated and wild P. acutifolius were intermingled with var. tenuifolius and P. parvifolius, signifying that allele diversity was ample in the wild and cultivated clade over a broad sense (sensu lato) evaluation. Genes Dreb2B and ERECTA harbored signatures of directional selection, represented by six SNPs correlated with the environmental drought indices. This suggests that wild tepary bean is a reservoir of novel alleles at genes for drought tolerance, as expected for a species that originated in arid environments. Our study corroborated that candidate gene approach was effective for marker validation across a broad genetic base of wild tepary accessions.

Objectives: The overall goal was to analyze genetic diversity in cultivars of Musa acuminata (Colla) and M. balbisiana (Colla), commonly grown in farms from Caldas department. Scope: Characterization of the genetic variability, at the molecular and morphological level of cultivars of M. acuminata and M. balbisiana, found in farms from Caldas farmers using morphological descriptors and fluorescent microsatellites. Methodology: Phenotyping evaluations comprised 57 morphological characters following the descriptors proposed by IPGRI for the Musa genus, and for genotyping evaluations, nine fluorescent microsatellites (Simple Sequence Repeats-SSR) were used to allow the precise identification of alleles. Additionally, cluster analyses were carried out independently for both morphological and genotypic characterizations under Principal Component Analysis (PCA) and Bootstrapping methods respectively. Main results: Positive and negative highly significant correlations were found for the morphological descriptors, where traits such as presence/ absence of male bud was the rule, as well as the diameter and perimeter of this trait, plus the diameter and perimeter of the peduncle, number of fruits, pseudostem height and fruit length contributed considerably to the variability among the cultivars allowing the discrimination of three main groups in the cluster analyzes. From the molecular perspective a total of 72 polymorphic alleles were obtained, with an average genetic diversity of 0,79, polymorphic information content (PIC) of 0,77 and heterozygosity of 0,48, showed a moderate degree of genetic differentiation (FST = 0,061) among Musa cultivars, generating three main sub-clusters based on their genetic dissimilarity. Conclusions: The identification of certain morphological traits showed to be suitable for the discrimination of Musa cultivars evaluated here. On the other hand, molecular characterization allowed to establish the genetic relationships among groups, also fluorescent SSR were highly informative and accurate, in such a way that can be considered suitable for characterizations in Musa varieties.

Grain amaranths are made up of three New World species of pseudo-cereals with C4 photosynthesis from the dicotyledonous family Amaranthaceae and the genus Amaranthus. They originate in two ecoregions of the Americas, namely, the inter-Andean valleys of South America and the volcanic axis and lowlands of Mexico and Central America. These correspond to two centers of domestications for Andean and Mesoamerican crops, with one cultivated species found in the first region and two found in the latter region. To date, no core collection has been made for the grain amaranths in the United States Department of Agriculture (USDA) germplasm system. In this study, our objective was to create a core for the 2,899 gene bank accessions with collection site data by town or farm site of which 1,090 have current geo-referencing of latitude and longitude coordinates. We constituted the core with 260 genotypes of Amaranthus, which we evaluated with 90 single-nucleotide polymorphism markers. Our goal was to distinguish between Andean and Mesoamerican gene pools of amaranths, including the cultivated species and three possible progenitor or wild relative ancestors along with two more species in an outgroup. Population structure, clustering, and discriminant analysis for principal components showed that Andean species Amaranthus caudatus and Amaranthus quitensis shared fewer alleles with Mesoamerican species Amaranthus cruentus and Amaranthus hypochondriacus, compared to each group individually. Amaranthus hybridus was a bridge species that shared alleles with both regions. Molecular markers have the advantage over morphological traits at quickly distinguishing the Andean and Mesoamerican cultivars and have the added benefit of being useful for following inter-species crosses and introgression.