Correction: Increasing atmospheric CO2 and canopy temperature induces anatomical and physiological changes in leaves of the C4 forage species Panicum maximum.

[This corrects the article DOI: 10.1371/journal.pone.0212506.].

Increasing atmospheric CO2 and canopy temperature induces anatomical and physiological changes in leaves of the C4 forage species Panicum maximum.

Changes in leaf anatomy and ultrastructure are associated with physiological performance in the context of plant adaptations to climate change. In this study, we investigated the isolated and combined effects of elevated atmospheric CO2 concentration ([CO2]) up to 600 µmol mol-1 (eC) and elevated temperature (eT) to 2°C more than the ambient canopy temperature on the ultrastructure, leaf anatomy, and physiology of Panicum maximum Jacq. grown under field conditions using combined free-air carbon dioxide enrichment (FACE) and temperature free-air controlled enhancement (T-FACE) systems. Plants grown under eC showed reduced stomatal density, stomatal index, stomatal conductance (gs), and leaf transpiration rate (E), increased soil-water content (SWC) conservation and adaxial epidermis thickness were also observed. The net photosynthesis rate (A) and intrinsic water-use efficiency (iWUE) were enhanced by 25% and 71%, respectively, with a concomitant increase in the size of starch grains in bundle sheath cells. Under air warming, we observed an increase in the thickness of the adaxial cuticle and a decrease in the leaf thickness, size of vascular bundles and bulliform cells, and starch content. Under eCeT, air warming offset the eC effects on SWC and E, and no interactions between [CO2] and temperature for leaf anatomy were observed. Elevated [CO2] exerted more effects on external characteristics, such as the epidermis anatomy and leaf gas exchange, while air warming affected mainly the leaf structure. We conclude that differential anatomical and physiological adjustments contributed to the acclimation of P. maximum growing under elevated [CO2] and air warming, improving the leaf biomass production under these conditions.

Asymmetric cytokinesis guide the development of pseudomonads in Rhynchospora pubera (Cyperaceae).

The late stages of microsporogenesis in the family Cyperaceae are marked by the formation of an asymmetrical tetrad, degeneration of three of the four nuclei resulting from meiosis and the formation of pseudomonads. In order to understand the cytological changes involved in the development of pseudomonads, a combination of 11 different techniques (conventional staining, cytochemistry procedures, immunofluorescence, FISH and transmission electron microscopy: TEM) were used to study the later stages of microsporogenesis in Rhynchospora pubera. The results demonstrated the occurrence of two cytoplasmic domains in the pseudomonads, one functional and the other degenerative, which are physically and asymmetrically separated by cell plate with an endomembrane system rich in polysaccharides. Other changes associated with endomembrane behaviour were observed, such as a large number of lipid droplets, vacuoles containing electron-dense material and concentric layers of endoplasmic reticulum. Concomitant with the isolation of degenerative nuclei, the tapetal cells also showed evidence of degeneration, indicating that both tissues under programmed cell death (PCD), as indicated by immunofluorescence and TEM procedures. The results are significant because they associate cellular polarisation and asymmetry with different cytoplasmic domains, and hence open new possibilities for studying cellular compartmentalisation and PCD.

Cytogenetic characterization reveals differences in nuclear organization of cystic cells among Brazilian species of Triatoma (Heteroptera, Reduviidae).

Cytogenetic studies in triatomines have described the occurrence of holokinetic chromosomes, heterochromatin distribution and the location of rDNA (ribosomal DNA) sites, but few aspects of nuclear organization in this group have been discussed. We have focused on ultrastructural and cytogenetic features and differences in cystic cells of seminiferous tubules between five species of Triatoma. Cystic cells showed evidence of polyploidy events and heterochromatic blocks appeared predominantly in the central region of the nuclei. Cytogenetic analyses showed that there was variation in chromocenter number between species, and that the central regions were AT-rich [DAPI+ (4',6-diamidino-2-phenylindole+)], whereas the periphery was CG-rich (CMA+). Another characteristic was the distribution of 45S rDNA, which differed according to the chromosomal location of this sequence. In all we have compared aspects of nuclear organization, polyploidy, heterochromatin, rDNA site distribution and methylation levels, as well as the relationships between five species of Triatoma from a cystic cell perspective.

Early meiosis in Rhynchospora pubera L. (Cyperaceae) is marked by uncommon ultrastructural features.

The family Cyperaceae has an unusual microsporogenesis in which tetrad formation does not occur. In addition, other cytological features are important, such as the occurrence of holokinetic chromosomes and post-reductional meiosis. We have examined the ultrastructural features of the pollen mother cell (PMC) of Rhynchospora pubera. Anthers of several sizes were analyzed using light and transmission electron microscopy. The PMC before meiosis presented a central nucleus and a regular profile of the nuclear envelope. During prophase I, the nucleus was in the abaxial region of the cell. This cellular polarization was accompanied by other marked ultrastructural features in the nuclear envelope. Morphological changes involved dilations of perinuclear cisterns and polarization of the nuclear pore complexes. The results show that polarization occurs in the initial phases of microsporogenesis in R. pubera, unlike other plant species.