Highly efficient system for the micropropagation and acclimatization of pineapple in vitro plants (Ananas comosus L. Merr, var. MD2)

The low acclimatization efficiency of pineapple seedlings obtained by in vitro culture has been one of the main limitations to massively scale micropropagation protocols. Various factors may be affecting the successful establishment of in vitro plants to ex vitro conditions, related to the plant and/or the environment and the management of seedlings. The objective of this study was to establish an efficient micropropagation and acclimatization system for the MD2 variety, with a high in vitro multiplication rate and a high greenhouse and field survival of pineapple in vitro plants. In the multiplication phase, the axillary buds were isolated and placed on a semisolid medium and three induction treatments with different concentrations of BAP (1.0, 3.0, 5.0 mg/L) and ANA (2.0 mg/L), were evaluated. After the third subculture, multiple shoots were transferred to a temporary immersion system (BIOMINT). During acclimatization and nursery phases, six treatments with different substrate compositions wereevaluated. The induction treatment IT3 (BAP 5.0 mg/L and ANA 2.0 mg/L) was selected for a significantly high multiplication rate. AT4 treatment (Soil + Coconut fiber + perlite 1:1:1) showed the highest survival rate (95%) and allowed the obtaining of well-developed plants. This system constitutes a valuable technology to introduce in vitro plants to the pineapple production scheme on a commercial scale

Floral Biology Studies in Habanero pepper (Capsicum chinense Jacq.) to Implement in a Cross-Breeding Program

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

Development of the ovule and seed of Habanero chili pepper (Capsicum chinense Jacq.): Anatomical characterization and immunocytochemical patterns of pectin methyl-esterification

32 p.-7 fig.-1 fig.supl.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.This work was supportedby Consejo Nacional de Ciencia y Tecnología (CONACYT-México) [grant number 219651] and the Spanish MINECO and European Regional Development Fund (ERDF/FEDER) [grant numbers AGL2014-52028-R and AGL2017-82447-R]Peer reviewe

Endogenous auxin accumulation/localization during zygotic and somatic embryogenesis of Capsicum chinense Jacq

37 p.-9 fig.Zygotic and somatic embryogenesis in plants is a fascinating event that is finely regulated through the expression of a specific group of genes and dynamic levels of plant hormones whose concerted action determines the fate that specific cells follow towards zygotic or somatic embryo development. This work studied different stages of Capsicum chinense Jacq. zygotic and somatic embryogenesis. HPLC quantification determined that the levels of indole-3-acetic acid (IAA) increase as the zygotic or somatic embryogenesis progresses, being higher at maturity, thus supporting a positive correlation between embryo cell differentiation and IAA increase. A monoclonal anti-IAA-antibody was used to detect IAA levels. Findings revealed a dynamic pattern of auxin distribution along the different embryogenic embryonic stages. In the early stages of zygotic embryos, the IAA gradient was observed in the basal cells of the suspensor and the hypostases, suggesting that they are the initial source of the IAA hormone. As embryogenesis proceeds, the dynamic of the IAA gradient is displaced to the embryo and endosperm cells. In the case of induced somatic embryogenesis, the IAA gradient was detected in the dividing cells of the endodermis, from where pre-embryogenic cells emerge. However, the analysis of somatic embryos revealed that IAA was homogeneously distributed. This study shows evidence supporting a correlation between IAA levels during zygotic or somatic embryogenesis in Capsicum chinense species.This manuscript received financing from CONACYT-México through the project with reference number PDCPN2016 3953. This study was funded by Project grant AGL2017-82447-R, funded by Spanish AEI and European ERDF/FEDER too.Peer reviewe

Indirect Somatic Embryogenesis: An Efficient and Genetically Reliable Clonal Propagation System for <i>Ananas comosus</i> L. Merr. Hybrid “MD2”

The objective of this study was to establish an efficient—direct or indirect—regeneration system for pineapple (Ananas comosus L.) plants, with a high rate of multiplication and that would preserve the genetic identity of the donor genotype (Hybrid ‘MD2’) in the regenerated plants. Ten treatments, with different concentrations of 2,4-Dichlorophenoxyacetic (2,4-D) and Picloram (P), in the absence or presence of 6-Benzylaminopurine (BAP), were used for in vitro morphogenesis induction, as well as histological and molecular techniques, in order to characterize the morphogenic responses induced. Significant differences between treatments tested, to induce callus and buds, were assessed by the Kruskal Wallis method and the Mann–Whitney U-tests. Different pineapple regeneration routes were identified, showing the high regeneration potential of this species. The medium containing 2 mg L−1 2,4-D and 2 mg L−1 BAP, where indirect somatic embryogenesis occurred, was selected as the most efficient treatment, with an average of 120 somatic embryos per explant, differing significantly from the rest of the treatments. It was also demonstrated that the pineapple plants regenerated in vitro preserved the genetic identity of the donor genotype, which represents a high degree of confidence for the application of indirect somatic embryogenesis for A. comusus clonal propagation

Indirect Somatic Embryogenesis: An Efficient and Genetically Reliable Clonal Propagation System for Ananas comosus L. Merr. Hybrid &ldquo;MD2&rdquo;

The objective of this study was to establish an efficient&mdash;direct or indirect&mdash;regeneration system for pineapple (Ananas comosus L.) plants, with a high rate of multiplication and that would preserve the genetic identity of the donor genotype (Hybrid &lsquo;MD2&rsquo;) in the regenerated plants. Ten treatments, with different concentrations of 2,4-Dichlorophenoxyacetic (2,4-D) and Picloram (P), in the absence or presence of 6-Benzylaminopurine (BAP), were used for in vitro morphogenesis induction, as well as histological and molecular techniques, in order to characterize the morphogenic responses induced. Significant differences between treatments tested, to induce callus and buds, were assessed by the Kruskal Wallis method and the Mann&ndash;Whitney U-tests. Different pineapple regeneration routes were identified, showing the high regeneration potential of this species. The medium containing 2 mg L&minus;1 2,4-D and 2 mg L&minus;1 BAP, where indirect somatic embryogenesis occurred, was selected as the most efficient treatment, with an average of 120 somatic embryos per explant, differing significantly from the rest of the treatments. It was also demonstrated that the pineapple plants regenerated in vitro preserved the genetic identity of the donor genotype, which represents a high degree of confidence for the application of indirect somatic embryogenesis for A. comusus clonal propagation