The Yucatan Peninsula is recognized as the center of genetic diversity of Habanero peppers ( Capsicum chinense Jacq.), which can be distinguished from those cultivated in other regions of the world by their aroma, taste, and—most of all—by their pungency. We evaluated three commercial varieties of chili peppers reported as being the hottest in the world: ‘Bhut Jolokia’, ‘Trinidad Moruga Scorpion’, and ‘Carolina Reaper’. The aim of our study was to determine the behavior of the pungency when cultivated under the edaphoclimatic conditions of Yucatan. Our results show that the three varieties registered greater contents in comparison with those reported in other regions of the world. ‘Carolina Reaper’—considered to be the hottest variety in the world, with a pungency of 2,200,000 Scoville heat units (SHU)—when cultivated in Yucatan, had a pungency of 3,006,330 SHU, which was greater than all the other varieties analyzed.

This study evaluated 29 F1 lines and the 11 genotypes of habanero peppers used in the crossbreeding program developed by the Scientific Research Center of Yucatan, México. A randomized complete block design with four repetitions was used. Eight plants of each of the genotypes were studied per block. A total of 22 qualitative and 18 quantitative descriptors established in the manuals of the International Plant Genetic Resources Institute (IPGRI) and the National Service for Seed Inspection and Certification (SNICS) was used. The multiple correspondence analysis of the qualitative traits explained 38.2% of the total variability. The trait that contributed the most to the qualitative variability identified was the presence of anthocyanins in the node. Principal component analysis showed that the first two axes explained 85.1% of the total variability and that capsaicin content and fruit pericarp thickness were the major contributors to the variation recorded. Based on these results, four F1 hybrids of habanero pepper were selected because of their promising traits for the different markets, i.e., high productive potential and/or high pungency. These traits are described in the section on Results.

Knowledge of the reproductive biology of a species is fundamental in order to develop an efficient program of genetic improvement by hybridization. The viability of the pollen, anther dehiscence, receptivity of the stigma and the anthesis of 12 improved lines of Habanero pepper were studied to develop a cross-breeding program. Among the results, the greatest number of flowers in anthesis was quantified at 8:00 a.m. for most genotypes. The dehiscence of the anther differed significantly in stages evaluated, observing in flower buds 100% of the closed anthers. The receptivity was positive in all the stages evaluated (before, during and after anthesis) and in all the genotypes, the most outstanding being the genotype AKN-08, which presented 100% of receptivity in the three stages evaluated. The viability of the pollen varied among the different conservation times evaluated (0, 24 and 48 h) while the highest percentage of viability (80%) and the largest number of seeds per fruit (56) were obtained when recently collected pollen was used (0 time). These results will have an important repercussion on the improvement of the Habanero pepper by increasing the efficiency of the programs to obtain hybrids and/or improved varieties.

Ovule and seed development in plants has long fascinated the scientific community given the complex cell coordination implicated in these processes. These cell events are highly conserved but are not necessarily representative of all plants. In this study, with the aim of obtaining information regarding the cellular patterns that follow the usual development of the ovule and the zygotic embryo, we carried out an integral anatomical study of the Capsicum chinense Jacq., floral buds and seeds at various days during maturation. This study allowed us to identify the main histo-morphological stages accompanying the transition of somatic cells into the macrospore, female gamete, and the zygotic embryogenesis. This knowledge is fundamental for future biotechnological research focused on solving the morphological recalcitrance observed during the in vitro induction of somatic or microspore embryogenesis in Capsicum. For the first time in C. chinense, we have described the hypostases, a putative source of plant growth regulators, and "the corrosion cavity", a space around the embryo. Additionally, the cell wall pectin-esterification status was investigated by immunohistology. At early stages of morphogenesis, the pectin is highly methyl-esterified; however, methyl-esterification decreases gradually throughout the process. A comparison of the results obtained here, together with the histo- and immunological changes occurring during the somatic and microspore embryogenesis, should help to elucidate the biochemical mechanisms that trigger the morphogenic events in Capsicum spp.

The variability and genetic parameters of seven agronomic characteristics were estimated for 11 genotypes, and high values of the phenotypic coefficient of variation (PCV) of capsaicin content (CC) were obtained. Heritability (h ² ) was high for yield per plant (YP; 0.98) and CC (0.93). The principal components analysis (PCA) revealed that the first three components explained 94.02% of the total variation; therefore, genotypes with higher YP values and fruit weight (FW) (AKN-08, ASBC-09) were placed in quadrant I. Those with greater CC and lowest YP and FW (MBI-11, RES-05) were placed in quadrant II. The greatest fruit length (RNJ-04) was placed in quadrant III. Those with the greatest number of fruits per plant (NBA-06, RKI-01, RHC-02, RHN-03, NKA-07, and MSB-12) were placed in quadrant IV. The results showed that the genotypes studied comprise an excellent source of genetic material for Habanero pepper improvement programs.