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Length and width of guard cells and variation in the appearance of stomata pores in the following Arum species: Arum italicum Mill., Arum maculatum var. maculatum L. and Arum maculatum var. immaculatum L. at Zablaće and Normanci location, and Arum alpinum var. pannonicum Terpo., Arum alpinum var. intermedium Schur. in Bilje at the eastern Slavonia and Baranya region were investigated. With regard to guard cells length and width and variation in the appearance of stomata pores, stomata of certain Arum species are considered to be of larger dimensions (≯38 µm). Arum species grown at Zablaće had the longest and widest guard cells as well as the greatest variation in the appearance of stomata pores, followed by those at Normanci, whereas species at Bilje location had the lowest values. The average length and width of the guard cells and variation in the appearance of stomata pores were larger at the lower than at the upper epidermis among each examined Arum species at each location. A significant difference in guard cells length and width and variation in the appearance of stomata pores at both upper and lower epidermis was determined for Zablaće and Normanci location, whereas there was no significant difference in those parameters at Bilje location.

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Diploid Anthoxanthum odoratum and tetraploid A. aristatum were compared with respect to stomatal guard cell lengths, and stomatal density at adaxial and abaxial surfaces of the lamina. Further, the genome size of both species was determined by flow cytometry, and the number as well as the chromosomal distribution of 5S and 45S rDNAs were examined using FISH with ribosomal DNA (rDNA) probes. The average length of stomatal guard cells in A. odoratum was shown to be greater than that for A. aristatum, but the ranges overlapped. Moreover, reduction in stomatal frequency was found at higher ploidy levels.The genome size was 6.863 pg/2C DNA for A. aristatum and 13.252 pg/2C DNA for A. odoratum. A. aristatum has four sites of 5S rDNA in its root-tip meristematic cells, whereas A. odoratum has six. Both species have six sites of 45S rDNA. Chromosomal localization of the rDNA varied, which suggests that chromosome rearrangements took place during Anthoxanthum genome evolution.

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The receptaculo-ovarial nectary of quince is located on the adaxial surface of the hypanthium. The glandular tissue is protruding out of the basal part of the receptacular tissue, but the apical part of the nectary is epimorphic. The glands can have various shapes if observed in the median longitudinal section of the flower and gland shapes are characteristic to the cultivars. The anisodiametrical cells of the nectarial epidermis are arranged in one or two rows. The surface of the nectary is covered by cuticle, the thickness of which depends on climatic conditions. Stomata of the nectary are mesoxeromorphic, the guard cells are sunken below the outer anticlinal wall of the epidermis cells. The investigated pear-shaped quince cultivars have more sunken stomata than the apple-shaped ones. Both the glandular tissue and the nectary parenchyma are the thickest on the basal part of the nectary, but taper on the apical part. The nectary parenchyma cells differ from the receptacular ones in shape and size. The phloem bundles, supplying the nectary, do not enter into direct contact with the secretory tissues.The morphological and histological differences that can be found between the nectary of cvs. ‘Konstantinápolyi’ and cvs. ‘Dunabogdányi’, as well as between the gland of the investigated apple-shaped cultivars and pear-shaped ones, can have taxonomic importance and could refer to the various degree of susceptibility of the cultivars to Erwinia amylovora .

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Micromorphological studies revealed the developmental changes in micropropagated plants of Morinda citrifolia L. from in vitro conditions to field environment. The lower relative humidity, higher light intensity and septic stressful conditions in the field environment could make gradual changes in the micropropagated plants so as to adapt the external environment. Arrested stomatal development, single guard cells and indistinct subsidiaries were observed in vitro with highest stomatal density (52.0±0.11) obtained in the ambient in vitro environment. The development of tissues, epidermal ornamentation, efficient stomatal functionality and vein-islets numbers (12.0±0.0) during in vivo transfer may help in acclimation of micropropagated plants under field conditions. Raphides were observed in the in vitro propagated as well as in vivo transferred plantlets. The gradual acclimatisation and ex vitro rooting technique increased the survival rate of plantlets in the field. The micromorphological changes resulting from in vitro to field environments are important to understand the development of tissues and adaptation of micropropagated plants, which could help in improvement in survivability during field trials.

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., Martinoia, E. (2004) Disruption of AtMRP4, a guard cell plasma membrane ABCC-type ABC transporter, leads to deregulation of stomatal opening and increased drought susceptibility. Plant J. 39 , 219–236. Martinoia E

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173 Mac Robbie, E. (1981): Effects of ABA in isolated guard cells. J. Exp. Bot. , 32 , 563–572. Mac Robbie E

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598 605 Schroeder, J. I., Fang, H. H. (1991): Inward-rectifying K + channels in guard cells provide a mechanism for low-affinity K uptake. Proc. Natl. Acad. Sci. USA , 88

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in soybean plants . J. Plant Physiol. 168 , 1562 – 1667 . 18. Kim , T. H. , Maik , B. , Hu , H. H. , Noriyuki , N. , Julian , I. S. ( 2010 ) Guard cell signal

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guard cells. Plant Physiol. 128 , 13–16. Hancock T. Nitric oxide is a novel component of abscisic acid signaling in stomatal guard cells Plant Physiol

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. 2012 . Regulation of stomatal movement and photosynthetic activity in guard cells of tomato abaxial epidermal peels by salicylic acid . Funct. Plant Biol. 39 : 1028 – 1037 . Rehman

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