Capsicum chinense is commercially the most important pepper species grown in the Caribbean. It is popularly used to impart pungency and flavor to Caribbean cuisine. However, unlike Capsicum annuum , which is the most commercially exploited domesticated species internationally, C. chinense has not been methodically collected or characterized for systematic improvement through plant breeding. The objectives of the study were to assess the diversity of C. chinense and its structure within the Caribbean basin and to determine its phylogenetic relationship to groups within South America. DNA isolated from 201 accessions of C. chinense , representing geographical regions where the species is found, were amplified using arbitrary primers to generate 138 polymorphic and reproducible random amplification of polymorphic DNA (RAPD) markers. Nei’s and Shannon’s diversity indices for C. chinense (0.28 and 0.419, respectively) were higher in South America compared with Central America or the Caribbean, corresponding to its putative center of diversity. The study showed the existence of three phylogenetic clusters within C. chinense. The largest cluster consisted of accessions from the Upper Amazon region, the Guianas including Venezuela, and the Lesser Antilles of the Caribbean. The other major cluster was represented by accessions principally from the Lower Amazon region. Another distinct but small cluster consisted of samples solely from the Greater Antilles of the Caribbean. The discovery of the three phylogenetic clusters within C. chinense may have potential for exploiting heterosis in breeding. The implications of the findings to the understanding of the phylogenetic origin and distribution of C. chinense are discussed.

Gene function studies in anthurium ( Anthurium andraeanum ) have been hindered by the low efficiency of stable transformation, the long regeneration time required as well as the genotype-dependent nature of Agrobacterium (Agrobacterium tumemaciens) -mediated transformation protocols. Agrobacterium -mediated transient expression assays can serve as an attractive alternative for investigating gene function once such assays are optimized. The effects of host factors (genotype, explant type, and developmental maturity of explants), Agrobacterium factors (strain, growth phase, and its concentration), media conditions (infiltration medium used, acetosyringone concentration, type of surfactant, and its concentration), and other experimental factors (infiltration time, cocultivation time, and vacuum infiltration) were investigated on the efficiency of Agrobacterium transient transformation, with replications, using transient expression of β-glucuronidase as an indicator. Although the efficiency of transient transformation was initially found to be highly host genotype-dependent, the genotypic differences in transient transformation efficiency diminished as the protocol was optimized. Agrobacterium strain GV3101 grown to an optical density at 600 nM (OD ₆₀₀ ) of 1.5 and resuspended to a final OD ₆₀₀ of 0.8 in infiltration medium [0.5% glucose, 10 m m 2-( N -morpholino) ethanesulfonic acid] supplemented with 100 μM acetosyringone and 0.05% of a non-ionic surfactant (S240), for an infiltration period of 16 hours and a cocultivation timeframe of 2 days yielded transient transformation efficiencies as high as 100%.

Reverse transcription quantitative real-time PCR (RT-qPCR) is a sensitive technique capable of accurately characterizing gene expression. However, the lack of suitable reference genes for sample normalization is an impediment to reliable expression studies. The aim of this study was to identify stable reference genes for RT-qPCR studies in Anthurium andraeanum (Hort.). Eight putative reference genes were partially cloned from anthurium using degenerate primers and RT-qPCR assays were developed. Total RNA was isolated from spathe tissues from different cultivars, color groups, developmental stages and harvesting times, and the reference genes were assayed using a RT-qPCR. Datasets were analyzed using ANOVA and reference genes were ranked based on stability using the coefficient of variation, geNorm and NormFinder approaches. CYP, UBQ5 and EF1α ranked amongst the most stable genes, except for studies involving development stages, where EF1α ranked poorly. Conversely, GAPDH displayed highly significant differences (P < 0.001) in expression across cultivars and color groups and ranked as the least stable. Gene expression levels varied with 18S > UBQ5 > (CYP, EF1α) > (ACT, IF4A) > (TUB, GAPDH). 18S expression levels were found to be 1000 fold greater than expression levels of UBQ5, the second highest expressed gene. geNorm pairwise variation analysis demonstrated that only two of the recommended reference genes were necessary for accurate normalization of RT-qPCR datasets.