Question

One of the impacts of climate change is an alteration of rainfall patterns with both an increase in large rainfall events and an increase in drought already beginning to show up in the climate record of many different areas of the globe. Currently researchers are working on creating strains of plants that will resist drought and are focused on both plant anatomy and on plant physiology. Think about adaptations that will aid plants faced with drought to help answer the next few questions.

1a. One trait that researchers are working on is attempting to change stomatal density, that is the number of stomata present per unit area on a plant. Explain how a change in stomatal density might result in plants that could withstand drought.

1b. If changes in stomatal density would allow plants to withstand drought better, then why don’t all plants already have this adaptation? Explain your answer.

Answer 1

Ans 1a. In most drought stress plants.Stomatal closure is the first reaction. Stomatal closure prevents water loss from transpirational pathways. Stomatal closure is mainly controlled by chemical signals such as abscisic acid (ABA) production in roots which are dehydrating . This process is valled hydropassive closure. Under drought conditions, excessive evaporation might cause disruption of photosynthetic activities. Thus plant leaves reduces their active stomatas and reduces stomatal density releasing less water.

1.bPlants respond to their changing environment in a complex, integrated way. There isinvolvement of genetic control of tolerance to abiotic stresses which i very complex, and highly influenced by other environmental factors and also by the developmental stage of the plant.The plant’s response to drought involves activation of genes present for the perception of drought stress and in the transmission of the stress signal.There are groups of genes which code for regulatory proteins that regulates the transduction of the stress signal and modulate gene expression. ABA or abscinic acid levels in the plant leads to the increase in response to water stress, causing closure of stomata and thus causing reduction of the level of water loss through transpiration from leaves. Different plants reacts differently to drought, some generate toleranve with activation of stress genes while some cannot sustain drought conditions. Plants like rice, maize etc are being genetic