stomata closure, osmotic adjustment ,release antioxidant defense and synthesis of protective micro molecules

Dr Niguse Chewaka thank you for your contribution to the discussion

Drought tolerance in plants is induced by closing stomata, shifting reactive oxygen species, and deep root growth in the case of jasmonic acid. Studies have revealed that JAs participate in stomata closing regulation as a result of drought stress. In response to drought stress, plants activate their drought response mechanisms, such as morphological and structural changes, expression of drought-resistant genes, synthesis of hormones, and osmotic regulatory substances to alleviate drought stress. Drought stress causes morphological and physiological responses in plants. Morphological responses occur in root elongation, leaf size, and the number of leaves. Physiologically roots can respond by transporting ABA to regulate stomata closure to reduce evaporation. These mechanisms include stomata responses, ion transport, activation of stress signaling pathways, and responses to protect photosynthesis from injury. Understanding these key factors will enable us to improve plant productivity during water stress. Under HT conditions, plants exhibit various mechanisms for surviving which include long-term evolutionary phonological and morphological adaptations and short-term avoidance or acclimation mechanisms such as changing leaf orientation, transpiration cooling, or alteration of membrane lipid compositions. Drought tolerance relies on the ability of plants to sustain physiological activities under severe drought stress conditions through the remodeling of gene regulation and metabolic pathways to reduce or repair the resulting stress damage. The bulk of water absorbed and transported through plants is moved by negative pressure generated by the evaporation of water from the leaves this process is commonly referred to as the Cohesion-Tension mechanism. Continuous transpiration occurring in all of the leaves of a plant creates a negative pressure in the water column (xylem). This exerts an upward pull on the water column, called transpiration pull. And thus, the water present in the xylem column transports up to the tip of the stem, leaves, etc. Water is transported in the plants with the help of conductive tissues and individual cells of the vascular system. Water moves along the water potential gradient and enters the root hairs and xylem through either apoplast or symplast pathways. Water is passively transported into the roots and then into the xylem. The forces of cohesion and adhesion cause the water molecules to form a column in the xylem. Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata.

Drought stress tolerance mechanisms in plants

Plants have evolved a variety of mechanisms to cope with drought stress, including:

• Morphological changes: Plants may develop smaller leaves, thicker waxy cuticles, and deeper root systems to reduce water loss and improve water uptake, respectively.
• Physiological changes: Plants may close their stomata (small pores on the underside of leaves) to reduce transpiration, and they may also produce stress hormones that help to regulate their water balance.
• Biochemical changes: Plants may produce osmotically active solutes, such as amino acids and sugars, to help maintain their cell water potential. They may also produce antioxidants to protect themselves from damage caused by reactive oxygen species (ROS) that are produced under drought stress.

Mechanisms involved in water movement in plants

Water movement in plants is driven by a combination of forces, including:

• Root pressure: Root pressure is generated by the active transport of ions into the roots, which creates a water potential gradient that drives water into the roots.
• Transpiration: Transpiration is the loss of water vapor from the leaves through stomata. Transpiration creates a negative water potential in the leaves, which draws water from the roots up the stem.
• Cohesion: Cohesion is the attraction between water molecules. This force helps to keep the water column from breaking as it is drawn up the stem.
• Adhesion: Adhesion is the attraction between water molecules and the walls of the xylem vessels. This force also helps to keep the water column from breaking.

Water movement in plants can be summarized in the following steps:

Drought stress can disrupt water movement in plants by reducing root pressure, transpiration, and the water potential of the leaves. However, plants can mitigate these effects through their drought stress tolerance mechanisms.

Conclusion

Plants have evolved a variety of mechanisms to cope with drought stress and to transport water throughout their bodies. These mechanisms allow plants to survive and thrive in even the harshest environments.

Dr Murtadha Shukur thank you for your contribution to the discussion

In response to drought stress, plants activate their drought response mechanisms, such as morphological and structural changes, expression of drought-resistant genes, synthesis of hormones, and osmotic regulatory substances to alleviate drought stress. Drought tolerance in plants is induced by closing stomata, shifting reactive oxygen species, and deep root growth in the case of jasmonic acid.These mechanisms include stomata responses, ion transport, activation of stress signaling pathways, and responses to protect photosynthesis from injury. Understanding these key factors will enable us to improve plant productivity during water stress. Under HT conditions, plants exhibit various mechanisms for surviving which include long-term evolutionary phonological and morphological adaptations and short-term avoidance or acclimation mechanisms such as changing leaf orientation, transpiration cooling, or alteration of membrane lipid compositions. Water can move through the roots by three separate pathways: apoplast, symplast, and transmembrane. In the apoplast pathway (apoplastic route), water moves through the spaces between the cells and in the cells walls themselves.Cold tolerance in plants is a complex process. Chilling or freezing temperatures can trigger the formation of ice in plant tissues, which causes cellular dehydration. On the other hand, plants can protect their body by preventing ice formation.