Ultrastructural changes during cryopreservation of plumules and embryos of coconut (Cocos nucifera L.)

This article aims to show the changes occurring during cryopreservation of embryos and plumules of coconut which are responsible of their death or survival. Embryos have been cryopreserved by preculture-dehydration for 24h, 28h, 30h, 34h, 38h and 48h on agar medium containing 600g/L of glucose combined with silica gel. The plumules were cryopreserved by encapsulation dehydration on solid medium containing 0.5 M, 0.75 M and 1M followed by dehydration with 40g of silica gel for different durations before rapid freezing. This study indicates that the damages undergone by seed samples can be divided into three types. The first stage of changes concerned the plasmolysis of cells with small vacuoles, condensation of chromatin, changing in the conformation of the DNA and the nucleus and stopping of mitosis. These types of changes are described in general in the context of a desiccation tolerance. The second degree of the changes was the retraction of the cytoplasm inside the cell, the increase in the periplasmic volume. The third degree of modification concerned the deformation of the walls, the invagination or the lysis of the plasma membrane resulting in the observation of distorted cells and and the bursting of the nucleus. These two types of modifications are irreversible and correspond to an absence of regrowth of the samples. Understanding the damage or changes that occur in cryopreserved cells is an important part of understanding how dehydration and frozen affect the viability of recalcitrant plants cells. These changes are made by dehydration and accentuated by freezing

Isolation of C-glycosyl xanthones from Coffea pseudozanguebariae and their location

The biochemical composition of leaves from Coffea pseudozanguebariae, a wild caffeine-free coffee species, was determined. Two phenolic compounds were extracted from leaves, separated and characterized. Their structures were elucidated by mass spectrometry, and 1D and 2D NMR spectroscopy and were shown to be mangiferin (1) and isomangiferin (2), which were the main polyphenol products. Multiphoton fluorescence imaging was performed to visualize polyphenol distribution in leaf cross sections. Consistent biochemical analysis cell imaging techniques on leaves revealed yellow fluorescence in the epidermis and parenchyma cells corresponding to xanthone compounds

Efficient method of transporting coconut (Cocos nucifera L.) zygotic embryos for cryopreservation of plumules by encapsulation/dehydration

Coconut is both socially and economically important crop in tropical and subtropical countries, thus the conservation of existing diversity of its germplasm is vital to maintain biodiversity, sustain crop production and utilisation of germplasm for crop improvement strategies. The recalcitrant storage behavior and large size of the coconut seed make it impossible to use as a germplasm storage material. Cryopreservation is an ideal means of long-term storage of germplasm which offers long-term storage capability with minimal storage space and maintenance requirements. The coconut embryo has been now adapted by various researchers for the purpose of germplasm exchange and it is now being routinely applied in germplasm collection and exchange activities with sufficient germination rates. The aim of the present study was to determine the effect of different coconut embryo transport/ storage methods [as solid endosperm plugs under cold temperature, embryos cultured in Solidified Agar Medium (SAM) or KCI solution under room temperature] on cryopreservation of plumules using encapsulation/dehydration method. The results revealed that plumules excised from embryos transported/stored in SAM and pretreated with 1.0M sucrose could by cryopreserved with 71.8% survival and 56% recovery rates. The survival and recovery could be further increased up to 77.5% and 65% respectively by supplementation of 1.0M sucrose with 20 µM ABA

Histo-cytological changes in Pelargonium apices during the cryopreservation process: Effect of the osmotic agent chosen for the preculture step

International audienceApex cryopreservation studies were undertaken to guarantee the safe, long-term conservation of a Pelargonium collection. Plant regrowth was obtained with a modified encapsulation-dehydration process. Choosing P. x peltatum 'Balcon Lilas' as a model, the main objective was to determine if sucrose is specific in conferring dehydration tolerance to apices. In the preculture medium sucrose was replaced by glucose, glucose with 3% sucrose, or sorbitol at similar osmolarities. None of the osmotic agents tested produced a level of tolerance to desiccation as high as that of sucrose. A high concentration of glucose was toxic and did not induce a dehydration tolerance. A histo-cytological study was performed on apices precultured with the various osmotic agents. Starch accumulation was only observed in most of the apex cells following sucrose preculture, not with the other osmotica. Other important differences concerned nucleus aspect, nucleolus presence, cell plasmolysis and cytoplasm constitutio