LEAVES: FORM & FUNCTION

... konulu sunumlar: "LEAVES: FORM & FUNCTION"— Sunum transkripti:

1 LEAVES: FORM & FUNCTION
Fonksiyon External Anatomy Internal Anatomy ???? Absisyon Transpirasyon Specialized Leaves

2 The Plant Body: Leaves Fonksiyon Güneş enerjisi ve CO2 toplayıcısı
Bazı bitkilerde belirli fonk. İçin özelleşmiş (modifiye) Transpirasyon

3 Dış Anatomi blade veya lamina marjin Vein (vascular bundles) petiole
stipule

4 EXTERNAL ANATOMY

5 Filotaksi – gövdede yaprak dizilimi

6 Yaprak çeşitleri: Simple, compound, peltate ve perfoliate
Simple leaf = bölünmemiş lamina, petiol tabanında tek axillary bud Compound leaf = leaflet (yaprakçık) halinde, leafletlarda axillary bud yok sadece compund yaprak tabanında bulunur pinnat-compound leaves: yaprakçıklar çiftli ve merkezi rachis üzerinde (gül) palmat-compound leaves: yaprakçıklar petiolün sonunda aynı noktadan çıkar (at kestanesi) Peltate leaves = petiol blade ortasından bağlanır Perfoliate leaves = sessile leave (yapışık yaprak) stemi çevreler

7 Leaf types – Pinnately & Palmately Compound Leaves

8

9 Peltate & Perfoliate Leaves
Mayapple Yellow Wort

10 Venation (Damarlanma) = yaprakta venlerin dağılımı
Netted-venation = bir veya birkaç dominant midvein vardır aralarda daha ince ağsı damarlar bulunur (dicotlar) Pinnately-veined leaves = midrib denen ana damar, burdan orjinlenen secondary veinler Palmately-veined leaves = veinler blade tabanından ayrılır (maple). Paralel venation = monocots (grasses, cereal grains); venler birbirine paralel Dikotomus venation = midrib veya büyük venler yok; benzer ebatta cok sayıda ven çatal oluşturarak tabandan iki farklı yöne gider, fan şekilli yaprak

11 Venation Types Netted or Reticulate Venation

12 Absisyon

13 C2H4 Abscission IAA Auxin (Oksin, IAA)
Etilen (C2H4) absisyona etkisi?? IAA C2H4

14 Etilenin etkileri - yaşlanma - yapraktaki oksin miltarı azalma - cellulase gibi duvarı inhibe eden enzimlerde artış - Hücrelerde şişme ve parçalanma

15 Abscission program Mobilizasyon Cork oluşumu Detachment (Ayrılma)

16 1. Mobilization Önemli materyalleri ana gövdeye transport eder
Proteins Chlorophyll Starch DNA signal aa Proteins, DNA, starch, etc + + enzymes aa, glucose

17 2. Cork formation Absisyon zonu altında:
Absisyon zonunun altındaki parenkimatik hücreler cell wall’da suberin ve lignin miktarını artırır (protective cork)

18 3. Detachment abscission zone:
Parenkima hücreleri bazi cell wall enzimleri salgılar (glucanases and pectinases); self digest Hücler su alır şişer

19 TRANSPIRATION Plants must supply water to all their tissues. It moves from the roots up the stem to the leaves by capillary action. The evaporation of water vapor from plant surfaces is called transpiration. Stoma neden var

20 Stomanın açılıp kapanması transpirasyonu düzenler
Az Su, düşük sıcaklık, ışık ; kapalı gündüz açık gece kapalı guard cells

21 Stomatal control

22 GUARD CELLS AND PLANT HOMEOSTASIS
kidney-shaped with thick inner walls and thin outer walls. When they become full of water (turgid) the unevenness of the walls causes them to bow outward and the stomate opens. When they lose water they become less turgid and the stomate closes. Guard cells gain and lose water by osmosis.

23 Stomatal guard cells Environmental factors are sensed by guard cells
Light intensity, temperature, relative humidity, intercellular CO2 concentration Integrated into well defined responses Ion uptake in guard cell Biosynthesis of organic molecules in guard cells This alters the water potential in the guard cells Water enders them Swell up %

24 Plants and water Bitkiler dehidrasyondan uzak durmak ister
water conservation X CO2 assimilation Bazı yapılar su dengesinde önemli 1: iyi gelişmiş root– to get water from soil 2: suya direnç götermeyen taşıma– xylem 3: leaf cuticle – reduces evaporation 4: stomata – controls water loss and CO2 uptake 5: guard cells – control stomata.

25 Habitatlara göre bitkiler
Mesophytes: plants adapted to a habitat with adequate water Xerophytes: plants adapted to a dry habitat Halophytes: plants adapted to a salty habitat Hydrophytes: plants adapted to a freshwater habitat

26 Hydrophyte: Nemli ortam

27 Xerophytes Sunken stoma Hair, air current Waxy cuticle waterproof
Rolled leaf Daha az stoma Küçük yaprak İyi kök sistemi

28 small leaf surface area less surface area for evaporation
Adaptation How it works Example thick cuticle stops uncontrolled evaporation through leaf cells small leaf surface area less surface area for evaporation conifer needles, cactus spines low stomata density smaller surface area for diffusion sunken stomata maintains humid air around stomata marram grass, cacti stomatal hairs (trichores) marram grass, couch grass rolled leaves marram grass, extensive roots maximise water uptake cacti

29 Left and right Epidermis of the cactus Rhipsalis dissimilis.
Left: View of the epidermis surface. The crater-shaped depressions with a guard cell each at their base can be seen. Right: X-section through the epidermis & underlying tissues. The guard cells are countersunk, the cuticle is thickened. These are classic xerophyte adaptations.

30 Transverse Section Through Leaf of Xerophytic Plant

31 .

32

33

34 Specialized or Modified Leaves
In pine trees, the leaves are adapted to living in a dry environment too. Water is locked up as ice during significant portions of the year and therefore not available to the plant; pine leaves possess sunken stomata, thick cuticles needle-like leaves hypodermis, which is an extra cells just underneath the epidermis –

35 he xylem and phloem in the center are surrounded by transfusion tis­sue composed of a mixture of parenchyma cells and short tracheids. The outer boundary of the transfusion tissue is marked by a single row of conspicuous cells comprising the endodermis. Notice also, depending on the species of pine, that the xylem and phloem may be in two adjacent patches (vascular bundles), or there may be a single vascular bun­dle. Much of the remaining tissue of the leaf is mesophyll, which is not divided into palisade and spongy layers The xylem of conifers consists of tracheids and lacks vessel members.  The phloem tubes lack the one-to-one relationship with a companion cell derived from the same progenitor cell. Instead certain nearby  parenchyma cells are modified into albuminous cells which presumably load/unload the phloem in a manner similar to companion cells. The  vessels are enclosed in tranfusion tissue consisting of parenchyma cells and tracheids. Note the resin canals.

36 Cotyledons or “seed leaves”
Çinlenen tohumun ürettiği ilk yaprak Bol miktarda besin (endospermden gelir)

37 Tendrils Garden Pea Tendrils – yaprağın blade kısmı indirgenmiş, sarılma özelliği

38 Böcek kapan Figure 11.8 (1) nitrojen Enzim turgor

39 Cotyledons or “seed leaves”

40 Leaves as Colorful Bracts