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The anatomy and ultrastructure of the short glandular trichomes occurring on young expanding leaves of Nicotiana tabacum were investigated using light and transmission electron microscopy. The objective of the present research was to characterize the cellular changes that occur during morphogenesis of short glandular trichomes, from initiation to senescence. Ultrastructural analysis of their secretory cells revealed characteristics common to gland cells: numerous mitochondria in highly organized cytoplasm, large nuclei, and an elaborate network of endoplasmic reticulum. Initial changes in nuclear and plastidial organization were observed at a more advanced secretory stage, marking the onset of senescence. During trichome senescence, gradual reduction of the cytoplasm density occurred along with structural changes of the plastids and the tonoplast. As a result of inward blebbing of the cytoplasm into the vacuole, membrane bound vesicular structures appeared in the vacuolar space. At the late secretory stage, marked by an increase in vacuolation and extraplasmic space, degenerative changes included further fragmentation of the cytoplasm and deterioration of the tonoplast. Multimembrane myelin bodies observed in the vacuolar space were indicative of membrane digestion although plasma membrane did not appear massively degraded.

The elucidation of molecular mechanisms underlying the leaf development can be facilitated by the detailed anatomical study of leaf development mutants. We present an analysis of leaf anatomy and morphogenesis during early developmental stages in has mutant of Arabidopsis thaliana. The recessive has mutation affects a number of aspects in plant development, including the shape and size of both cotyledons and leaves. The earliest developmental observations suggest almost synchronous growth of the first two leaf primordia of has mutant. No significant disruption of the cell division pattern in the internal tissue is observed at the earliest stages of development, with the major anatomical difference compared to wild type primordia being the untimely maturation of mesophyll tissue cells in has mutant. At the stage of leaf blade formation, structure disruption becomes clearly evident, by irregular arrangement of the cell layers and the lack of polarity in juvenile has leaves. One distinguishing feature of the mutant leaf anatomy is the absence of mesophyll tissue differentiation. Altered has mutant leaf morphology could be at least partially accounted for by the ectopic STM activity that was found at the base of leaf primordia during early stages of leaf development in has plants. Ministry of Science and Technological Development of Serbia [173015]

The potential of somatic embryogenesis induction was examined by in vitro growing of isolated ovules of Pinus heldreichii (Christ.) on nutrient media. The induction of embryogenic tissue was stimulated by Gresshoff and Doy (GD) medium with nitrogen compounds reduced to one half and with 0.5 mg/l BA and 2.0 mg/l 2.4-D. Still, the most important factor in this process was the development stage of embryos in the ovule. An induction frequency of 10% was obtained on the ovules in which embryos were in the pre-cotyledonary stage. When the dominant embryo in the ovule was in the cotyledonary stage, the induction frequency was lower or absent. Proliferation of embryogenic tissue was achieved on the media with reduced concentration of growth regulators, and the initial stages of embryo maturation were obtained on the media with ABA and 5% sucrose. Izolovane ovule Pinus heldreichii (Christ.) gajene su in vitro na hranljivim podlogama radi ispitivanja mogućnosti indukcije somatske embriogeneze. Hranljiva podloga Gresshoff and Doy (GD) sa azotnim jedinjenjima, smanjenim na polovinu i BA 0.5 mg/L i 2.4-D 2.0 mg/L, stimulisala je indukciju embriogenog tkiva. Ipak, najvažniji faktor u ovom procesu bio je stadijum razvića embriona u ovuli. Frekvencija indukcije od 10% dobijena je na ovulama u kojima su embrioni bili u prekotiledonarnom stadijumu razvića. Kada je dominantni embrion u ovuli bio u kotiledonarnom stadijumu razvića, frekvencija indukcije bila je manja ili je nije ni bilo. Proliferacija embriogenog tkiva dobijena je na podlogama sa smanjenom koncentracijom regulatora rastenja, a početni stadijumi sazrevanja embriona na podlogama sa ABA i 5% saharoze. Projekat ministarstva br. 143026B

In this study, the effect of plant growth regulators on leaf morphogenesis of the recessive T-DNA insertion mutant of Arabidopsis thaliana was analyzed. The morpho-anatomical analysis revealed that leaves of the has mutant are small and narrow, with lobed blades and disrupted tissue organization. When has plants were grown on the medium supplied with plant growth regulators: benzylaminopurine (BAP) or ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), the leaf anatomy was partially restored to the wild type, although plants still exhibited morphological abnormalities. Serbian Ministry of Science [143026B]

Micromorphology, distribution, and histochemistry of the trichomes of Thymus lykae were studied using scanning electron microscopy (SEM)and confocal laser scanning electron microscopy (CLSM). The leaves, stem, and calyx bear numerous glandular and non-glandular trichomes. Two types of glandular trichomes are identified - peltate and capitate. Results of histochemical tests showed positive reactions to polysaccharides, proteins, and lipids. Yellow autofluorescence of secreted material was noticed in peltate and capitate trichomes. Strong reddish-yellow autofluorescence of the lipophilic and hydrophilic secreted material was observed with CLSM. Mikromorfologija, distribucija i histohemijska analiza trihoma kod vrste Thymus lykae urađena je korišćenjem skening elektronskog mikroskopa i konfokalnog laserskog skening mikroskopa. Nežlezdane, negranate i dva tipa žlezdanih trihoma - peltatne i kapitatne opisane suuovom radu. Brojne nežlezdane i žlezdane trihome nalazile suse kako na listovima (i na licu i na naličju)tako i na stablu i na čašici. Rezultati histohemijskih istraživanja pokazala supozitivne reakcije na polisaharide, lipide i proteine. Sekretorni produkti unutar peltatnih trihoma imali sujako žutu autofluorescenciju, dok je u kapitatnim trihomama zapažena slabija autofluorescencija. Korišćenjem CLSM uočena je jarko crveno-žuta autofluorescencija lipofilnih i hidrofilnih sekretornih materija u žlezdanim trihomama. Projekat ministarstva br. 143049

The potential for somatic embryogenesis in zygotic embryo and megagametophyte cultures of Pinus heldreichii was examined. Somatic embryogenesis was initiated from megagametophytes containing immature zygotic embryos at early stages of development. An induction frequency of up to 6.7% was obtained on Gresshoff and Doy medium in the presence of 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l benzyladenine (BA). Formation and further proliferation of embryogenic tissue were achieved upon transfer of explants to a medium with reduced levels of growth regulators. Somatic embryos are being cultured for further development. . U kulturi izolovanih zigotskih embriona i ovula munike (Pinus heldreichii) ispitivan je efekat hranljive podloge i regulatora rastenja na indukciju somatske embriogeneze. Somatska embriogeneza je indukovana u kulturi ovula koje su sadržavale embrione na ranom stupnju razvića. Najviša frekvencija indukcije od 6.7% postignuta je kada su ovule 5 dana gajene na Gresshoff i Doy (GD) hranljivoj podlozi u prisustvu 2,4-D 2 mg/l i BA 0.5 mg/l, a zatim prenete na GD podlogu u kojoj je koncentracija regulatora rastenja bila 5 puta niža. U cilju dugotrajnog održavanja u kulturi, embriogeno tkivo je izolovano i gajeno na GD podlozi sa 2,4-D 0.2 mg/l i BA 0.05 mg/l. Mikroskopskom analizom je utvrđeno da se tkivo sastoji od brojnih embriona na ranim stupnjevima razvića. Za klonalnu propagaciju ove značajne endemoreliktne četinarske vrste u kulturi in vitro, neophodna su dalja istraživanja sa ciljem povećanja frekvencije indukcije somatske embriogeneze, kao i frekvencije sazrevanja embriona. . null

In this work, we analyzed the developmental anatomy of cotyledons and leaves in the has mutant of Arabidopsis thaliana. It is a recessive T-DNA insertion mutation that causes changes in the size, shape, and tissue organization of the cotyledons and leaves of has plants. Analysis of has cotyledons revealed a prominent decrease in the cell number and an increase in the area of cotyledon cells and intercellular spaces of has plants. At early stages of development, has leaves are fingerlike structures, but later they develop small, lobed blades with rare trichomes. An important characteristic of the mutant leaf anatomy is the absence of mesophyll tissue differentiation. In addition, both cotyledons and leaves display a disrupted pattern of vascular bundles. Furthermore, mutant plants are defective in root and shoot morphology, indicating that the has mutation affects a number of aspects in plant development. null

Wild-type and the handshake (has) mutants in Arabidopsis thaliana were analyzed. Compared to the wild-type, has mutants display a number of morphological alterations, which can largely be traced back to altered meristem function. Analyses of apical meristem of mutant plants showed that mutation affected meristem structure and patterns of STM expression. null