"Water in plant (its uptake and distribution)"

1. "Water in plant (its uptake and distribution)" Jiye RHEE jrhee@jcu.prf.cz

2. KEBR562- Small plant physiology – Chapter : Water in plant Water Balance of Plants Water channel protein (Aquaporin)

3. KEBR562- Small plant physiology – Chapter :Water in plant Water Balance of Plants Water channel protein (Aquaporin) • Differences in : • Water vapor concentration • Hydrostatic pressure • Water potential

4. KEBR562- Small plant physiology – Chapter : Water in plant • Water moves through soil by BULK FLOW • ‘ BULK FLOW’ • - connected movement of groups of molecules all together, • most often in response to a pressure gradient • Water absorption from Soil

5. KEBR562- Small plant physiology – Chapter : Water in plant Plant roots

6. KEBR562- Small plant physiology – Chapter : Water in plant • Water uptake in the roots • Apoplast pathway : water moves through cell walls without crossing any membranes • Transmembrane pathway : enter a cell on one side, exists the cell on the other side, • enter next cell , and so on • 3. Symplast pathway : via plasmodesmata • - At the endodermis- Casparian Strip

7. KEBR562- Small plant physiology – Chapter Water in plant

8. KEBR562- Small plant physiology – Chapter : Water in plant

9. KEBR562- Small plant physiology – Chapter : Water in plant • Water transport through xylem • - consist of two types of tracheary elements • Tracheids • Vessile elements

10. KEBR562- Small plant physiology – Chapter : Water in plant • Water transport through xylem • Plants can get embolism tool • Air bubbles can form in xylem • Cavitation

11. KEBR562- Small plant physiology – Chapter : Water in plant • Venation of a tobacco leaf • The tensions needed to pull water through • the xylem are the result of evaporation of • water from leaves

12. KEBR562- Small plant physiology – Chapter : Water in plant Water evaporation in the leaf affect the xylem Tension or negative pressures originate in leaves Transpiration pull As the radius of curvature decreases, the pressure decreases (become more negative)

13. KEBR562- Small plant physiology – Chapter : Water in plant Water pathway through the leaf

14. KEBR562- Small plant physiology – Chapter : Water in plant • Water vapor diffuse quickly in air • Transpiration from the leaf depends on two factors: • One, Difference in water vapor concentration between leaf air paces and the atmosphere • Two, The diffusional resistance of the pathway from leaf to atmosphere • Two components: • Leaf stomatal resistance • Boundary layer resistance

15. KEBR562- Small plant physiology – Chapter : Water in plant • Boundary layer resistance • Still air • Windy conditions

16. KEBR562- Small plant physiology – Chapter : Water in plant • Stomatal control • Remember the way cuticle? • Regulate water loss in plants and the rate of CO2 uptake • OPEN/CLOSED

17. KEBR562- Small plant physiology – Chapter : Water in plant Stomatal guard cells Stomatal resistance can be controlled by opening and closing the stomatal pores. Specialized cells- The Guard cells Two main types : Monocot and grasses – Dumbbell shape, pore is a long slit Dicot – kidney shape Q: When water is limited or abundant?

18. KEBR562- Small plant physiology – Chapter : Water in plant The radial alignment of the cellulose microfibrils a kidney shape stoma a glasslike stoma

19. KEBR562- Small plant physiology – Chapter : Water in plant Representative overview of water potential and its components SOIL-PLANT-ATMOSPHERE continuum

20. KEBR562- Small plant physiology – Chapter Water in plant Summary • Water is the essential medium of life • Land plants faced with dehydration by water loss to the atmosphere • There is a conflict between the need for water conservation and the need for CO2 assimilation • This determines much of the structure of land plants • 1. extensive root system – to get water from soil • 2. low resistance path way to get water to leaves – xylem • 3. leaf cuticle – reduces evaporation • 4. stomata – controls water loss and CO2 uptake • 5. guard cells – control stomata

21. KEBR562- Small plant physiology – Chapter : Water in plant Water Balance of Plants Water channel protein (Aquaporin)

22. KEBR562- Small plant physiology – Chapter : Water in plant • Structure • NPA motif, ar/R selectivity filter • Five main homologous subfamilies : • Plasma membrane Intrinsic Protein (PIP) • Tonoplast Intrinsic Protein (TIP) • Nodulin-26 like Intrinsic Protein (NIP) • Small basic Intrinsic Protein (SIP) • X Intrinsic Protein (SIP)

23. KEBR562- Small plant physiology – Chapter Water in plant Cell pressure probe Meniscus

24. KEBR562- Small plant physiology – Chapter Water in plant Function expression of Aquaporin genes Xenopusoocyte

25. KEBR562- Small plant physiology – Chapter Water in plant Relative volume H2O FgPIP2 H2O CuPIP1

26. KEBR562- Small plant physiology – Chapter Water in plant Questions 1. Explain, in terms of water potential how water moves from the soil to the endodermis in a root 2. Explain why, in summer, the diameter of a branch is smaller at noon than at midnight