AULA TEÓRICA. Ana Monteiro

Transcrição

1 AULA TEÓRICA Ana Monteiro SUMÁRIO Parênquimas: origem, funções e distribuição. Tecidos de suporte: Colênquima e esclerênquima: características histológicas, origem, funções e distribuição.

2 PARÊNQUIMAS Termo introduzido por Nehemiah Grew em 1682 Em geral, refere-se a tecidos com pouca especialização mas que podem estar envolvidos em funções muito diversas Por desdiferenciação voltam a células meristemáticas No corpo primário o parênquima desenvolve-se a partir do meristema fundamental Grandes partes do corpo da planta tal como: a medula, todas ou quase todas as células da zona cortical, o periciclo, o mesófilo das folhas, parte carnuda dos frutos, órgãos de reserva. No xilema e floema também ocorrem células de parênquima par. Lenhoso (ver mais tarde)

3 PARÊNQUIMAS características -tecido simples e permanente; -células vivas ricas em água; -com um núcleo proeminente; -paredes finas; -parede cellular apenas 1ª, celulósica; -sem lenhina; -pouco ou nada diferenciadas; -os parênquimas são os tecidos menos especializados nas plantas

4 Parênquima clorofilino MESÓFILO Parênquima clorofilino - em paliçada - lacunoso

5 SUBSTANCIAS RESERVA e SECRETORAS

6 PARÊNQUIMA DE RESERVA GRÃOS DE AMIDO

7 PARÊNQUIMA DE RESERVA GRÃOS DE AMIDO embrião do feijoeiro - corados pela iodina batata natomy/03.html Micrography Of Isolated Potato Starch Grains Viewed In Polarised Light Clearly Showing Growth Rings And The Characteric Maltese Cross With Its Origin At The Grains Hilum Stock Footage Video Getty Imageswww.gettyimages.com Search by imagecarbohydrate - Food Type,Cereal Plant,Color Image,Dieting,Film,Food,HD Format,Horizontal,Light Micrograph,Maltese Cross,Microscope,Raw Potato,Real Time,Solanum,Tree,Tree RingPhotographer Science Photo LibraryCollection: Photolibrary Video

8 PARÊNQUIMA DE RESERVA GRÃOS DE AMIDO

9 PARÊNQUIMA DE RESERVA CARIOPSE

10 PARÊNQUIMA DE RESERVA GRÃOS DE AMIDO

11 Parênquima medular e cortical Plant Cell Biology - by GR Kantharaj Root Structure and Function Penetration of Soil Gravitropism Downward Growth Water and Mineral Intake Conduction (Xylem and Phloem) Storage of Materials. - ppt downloadslideplayer.com Search by imageroot Vascular Cylinder and Cortex Ranunculus acris - buttercup Cortex Endodermis Meta- xylem Phloem Pericycle Proto- xylem Endarch: protoxylem is insi

12 PARÊNQUIMA aerífero

13 PARÊNQUIMA aerifero

14 PARÊNQUIMA aerifero Transverse sections of (a) adventitious root of rice showing lysigenous aerenchyma (formed as a consequence of senescence of specific cells in primary cortex followed by their death due to autolysis), and (b) lateral root of Rumex hydrolapathum showing schizogenous aerenchyma (is formed by separation of cells (without death) and is found in some wetland species and particularly dicots). (a) taken 50 mm behind the root apex, (b) taken 5 mm behind the root apex. (Micrographs courtesy of W. Armstrong).

15 PARÊNQUIMA aerifero lacunas par. clorofilino feixes vasculares epiderme Caule Juncus communis Moreira, 2010, Anatomia das Plantas. Estruturas, ISAPress

16 PARÊNQUIMA aerifero

17 PARÊNQUIMA aerifero

18 PARÊNQUIMA aerifero

19 Tipos de Colênquima Topo,esq.- angular Topo, dir. - anular Em baixo, esq.- laminar Em baixo, dir. - intercelular angular laminar A- c.lg. B e C - c.t. 1- parede primária espessada ( área branca) (Structure des Plantes Bowes, 1996)

20 Colênquima What are collenchyma cells? What are the main functions? Their thick cell walls are composed of the compounds cellulose and pectin. These cells are often found under the epidermis, or the outer layer of cells in young stems and in leaf veins. Collenchyma, SEM Crédito: BIOPHOTO ASSOCIATES Creative nº: Color enhanced scanning electron micrograph (SEM) of transverse section of the collenchyma, thick walls, no intercellular spaces. Magnification 900x

21 Colênquima - síntese

22 Colênquima cel. Vivas Collenchyma has remained in the shadow of commercially exploited mechanical tissues such as wood and fibers, and therefore has received little attention since it was first described. However, collenchyma is highly dynamic, especially compared with sclerenchyma. It is the main supporting tissue of growing organs with walls thickening during and after elongation. In older organs, collenchyma may become more rigid due to changes in cell wall composition or may undergo sclerification through lignification of newly deposited cell wall material. While much is known about the systematic and organographic distribution of collenchyma, there is rather less information regarding the molecular architecture and properties of its cell walls. Devido ao facto da sua parede primária possuir entre a matrix de cellulose, hemiceluloses e matérias pécticas as suas células possuem plasticidade (irreversível) c.t. pecíolo de Sanicula europeae Structure des Plantes, Bowes, 1996

23 Colênquima Where is the collenchyma located: in A or in B?

24 Colênquima exemplos de táxones Colênquima laminar paredes tangenciais Sambucus nigra, Cucurbita, Sanguisorba, Rhoeo, Eupatoria Colênquima angular - cantos das células Ficus, Vitis, Ampelopsis, Polygonium, Beta, Rumex, Boehmeria, Morus, Cannabis, Pelargonium, Foeniculum Colênquima anular todas as paredes de igual modo Lactuca Foeniculum vulgare (funcho)

25 Esclerênquima

26 Esclerênquima Deriva do grego skleros, que significa duro Tecido com função de suporte, formado em geral por células sem protoplasma quando maduras, e com espessa parede secundária, lenhificada e elástica. inserido frequentemente noutros tecidos O esclerênquima é dividido em. escleritos - células curtas com numerosas pontuações fibras - células alongadas com menos pontuações

27 2016/2017 Esclerênquima

28 braquiescleritos (idioblastos) são pequenos e isiodiamétricos, ocorrem no cortex, medulla e floema de caules (Cinnamonum, caneleira) polpa de frutos (Pyrus, pêra, foto em baixo) plant_anatomy/09.html

29 Astroescleritos em folhas de nenúfar (Nymphae odorata) Biology of Plants, Raven et al. 1999

30 Macroescleritos tegumento do feijoeiro (Phaseolus) Osteoesclerito em semente de soja (Glycine max)

31 Transverse section of leaf of yucca (Yucca). Yuccas have large, thick leaves that have a tough, leathery texture due to having many bundles of fiber cells. The fiber bundles are recognizable in the high magnification view (below, at the bottom of this page) as consisting of hundreds of fibers located just interior to the epidermis and hypodermis. Because these fibers are not part of the xylem, they are extraxylary fibers. Each of the two big masses of fibers has a lighter region along its inner edge; that region is a bit of phloem and xylem. Because the bundle has both vascular tissue and many fibers, it is a fibrovascular bundle. At the center of the micrograph is another fibrovascular bundle in which the vascular tissue is more abundant: the red cells in the center are xylem conducting cells, the very tiny green cells above the xylem are phloem cells, and above and below the conducting cells are two arc of red fiber cells. The low magnification view shows that fibrovascular bundles constitute a large fraction of the leaf s volume, with the fiber-rich type of fibrovascular bundle being abundant along the leaf s surface, the conducing cell-rich type of bundle being restricted to the interior of the leaf. The fibrovascular bundles of yuccas, agaves and other plants are extracted and used to make rope and cloth; the people that do that refer to the whole fibrovascular bundle as a fiber so it is necessary to be careful when reading about sizes of fibers : a fiber reported to be ten or 20 cm long will be a bundle, not a single cell. FIBRAS

32 FIBRAS Fibras periciclicas - derivam do procâmbio, são floémicas Structure des Plantes, Bowes, 1996 c.t. caule do LINHO (Linum usitatissimum) 1- epiderme 2- medula parenq. 3- cortex 4- fibras periciclicas (0,8-6,9 cm comp.) 5- elementos condutores do floema 6- câmbio vascular 7 - xilema secundário

33 FIBRAS floémicas Transverse section of linden tree (Tilia). These two micrographs show woodxylem (at the bottom) and secondary phloem (the upper part), the high magnification shows the cambial region where the wood is adjacent to the phloem. The red bands of cells in the secondary phloem consist of many phloem fibers, which are so narrow and have such thick walls that only a few have their lumens visible as small white dots.

34 c.t. FIBRA GIMNOSPÉRMICAS x parede secundária duma fibra, espessa e em camadas. As camadas são zonas de diferente densidade devido a variações na forma como os componentes da parede se depositaram durante o desenvolvimento da célula Botany Moore et al., 1995

35 FIBRAS c.t. Transverse section of leaf of dracaena (Dracaena). Dracaena has long strap-shaped leaves that are strengthened by bundles of fibers, and it has both fibrovascular bundles (the single large bundle in the center) and fiber bundles (the three small bundles that consist of just fibers). Fibers in the fibrovascular bundle completely encircle the conducting tissues, creating a strong sheath, and almost certainly making it very difficult or impossible for the vascular tissues to either give off water pick up sugars from the surrounding leaf tissue

36 FIBRAS c.t. Folha da cana-do-açúcar Transverse section of leaf of sugar cane (Saccharum officinale). Even leaves that are much smaller, thinner and more delicate than those of yuccas or dracaenas often have masses of fibers along their edges, as seen here along the margin of this sugar cane leaf. Because the edge is reinforced with extraxylary fibers rather than just consisting of parenchyma, it is much less likely to be torn by wind.

37 FIBRAS Fibrotraqueídos e fibras libriformes aparecem no xilema

38 FIBRAS libriformes c.l.t. The long cells here are fibers. Because they are part of the wood, they are xylary fibers (wood is a type of xylem called secondary xylem). These fibers are so fiber-like (long, thick walls, small pits) they are the type of xylary fiber known as libriform fibers. Simple pits Tangential section of wood of Zygogynum

39 Fibrotraqueídos L.S longitudinal section; T.S. Tangengial section

40 Fibras gelatinosas fibras com substâncias do tipo gelatinoso na parte interna, da parede 2ª. Exemplos: Aloe vera, Chia seeds

41 Ana Monteiro Perguntas: What are the characteristics of parenchymatous cells? Answer: slide 3 What is collenchyma cells? Answer: cells are elongated cells with irregularly thick cell walls that provide support and structure. Their thick cell walls are composed of the compounds cellulose and pectin. These cells are often found under the epidermis, or the outer layer of cells in young stems and in leaf veins. What are the main functions of collenchyma? Answer: It provides mechanical strength to the petiole, leaves and stem of young dicot plants. Collenchyma confers flexibility to various parts of the plant like petiole and stem, allowing for easy bending without breakage. It allows for growth and elongation of plant organs. Collenchyma present in leaves also prevents them from tearing. The living cells of collenchyma store food. Collenchyma when containing chlorophyll performs the function of photosynthesis. What is sclerenchyma cells? Types of cells? What are the main functions of sclerenchyma?