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LEAVES: FORM & FUNCTION. Fonksiyon External Anatomy Internal Anatomy ???? Absisyon Transpirasyon Specialized Leaves. The Plant Body: Leaves. Fonksiyon Güneş enerjisi ve CO 2 toplayıcısı Bazı bitkilerde belirli fonk. İçin özelleşmiş (modifiye) Transpirasyon. Dış A natomi. - PowerPoint PPT Presentation
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LEAVES: FORM & FUNCTION
• Fonksiyon• External Anatomy
• Internal Anatomy ????• Absisyon
• Transpirasyon• Specialized Leaves
The Plant Body: Leaves
• Fonksiyon– Güneş enerjisi ve CO2
toplayıcısı– Bazı bitkilerde belirli fonk.
İçin özelleşmiş (modifiye)– Transpirasyon
Dış Anatomi• blade veya lamina
• marjin
• Vein (vascular bundles)
• petiole
• stipule
EXTERNAL ANATOMY
Filotaksi – gövdede yaprak dizilimi
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
Leaf types – Pinnately & Palmately Compound Leaves
Peltate & Perfoliate Leaves
MayappleYellow Wort
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
Venation Types
Netted or Reticulate Venation
Absisyon
Abscission
Auxin (Oksin, IAA) Etilen (C2H4) absisyona etkisi??
IAA
C2H4
• Etilenin etkileri - yaşlanma
- cellulase gibi duvarı inhibe eden enzimlerde artış - Hücrelerde şişme ve parçalanma
- yapraktaki oksin miltarı azalma
Abscission program1. Mobilizasyon
2. Cork oluşumu
3. Detachment (Ayrılma)
1. MobilizationÖnemli materyalleri ana gövdeye transport eder
– Proteins– Chlorophyll– Starch– DNA
aa
enzymes
Proteins, DNA, starch, etc
aa, glucose
signal+
+
2. Cork formation – Absisyon zonu altında:
• Absisyon zonunun altındaki parenkimatik hücreler cell wall’da suberin ve lignin miktarını artırır (protective cork)
3. Detachment – abscission zone:
• Parenkima hücreleri bazi cell wall enzimleri salgılar (glucanases and pectinases); self digest
• Hücler su alır şişer
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
• Stomanın açılıp kapanması transpirasyonu düzenler
• Az Su, düşük sıcaklık, ışık ; kapalı
• gündüz açık gece kapalı
• guard cells
Stomatal control
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 gainand lose water byosmosis.
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 40-100%
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.
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
Hydrophyte:Nemli ortam
Xerophytes
• Sunken stoma
• Hair, air current
• Waxy cuticle waterproof
• Rolled leaf
• Daha az stoma
• Küçük yaprak
• İyi kök sistemi
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)
maintains humid air around stomata
marram grass, couch grass
rolled leaves maintains humid air around stomata
marram grass,
extensive roots maximise water uptake cacti
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.
Transverse Section Through Leaf of Xerophytic Plant
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 –
Cotyledons or “seed leaves”
Çinlenen tohumun ürettiği ilk yaprakBol miktarda besin (endospermden gelir)
Tendrils
Garden Pea
Tendrils – yaprağın blade kısmı indirgenmiş, sarılma özelliği
Figure 11.8 (1)Böcek kapan
• nitrojen• Enzim• turgor
Cotyledons or “seed leaves”
Leaves as Colorful Bracts