Question

Osmotic stress at membrane level and photosystem ii activity in two c4 plants after growth in elevated co2 and temperatur

Answer 1

Answer:

In the last two decades, several studies have evaluated plant physiology, growth and survival under forecasted climate changes and the effects of these environmental factors in plants are started to be understood. However, there are few studies evaluating such effects at the tissue or cellular level, especially for plants with photosynthetic C4 metabolism that are believed to respond less to elevated CO2 concentration. For this reason, we tested maize and pearl millet plants to consider cellular physiological responses to induce osmotic stress and acute heat shock. Plants were grown under elevated CO2 concentration and temperature, simulating global climate changes and then were subjected to osmotic stress and acute heat shock in vitro. The results indicated that the growth under elevated CO2 and temperature improved cellular tolerance to osmotic stress and acute heat shock for both species, but maize seemed to benefit more from increased CO2 concentration whereas pearl millet seemed to benefit more from increased temperature. Taken together, the results indicated that the current and expected global climate changes, besides operating differentially in these two species, can similarly affect other C4 plant species in different ecosystems whether undisturbed or managed.

Answer 2

Answer:

• Crops with the C(4) photosynthetic pathway are vital to global food supply, particularly in the tropical regions where human well-being and agricultural productivity are most closely linked.
• While rising atmospheric [CO(2)] is the driving force behind the greater temperatures and water stress, which threaten to reduce future crop yields, it also has the potential to directly benefit crop physiology.
• The nature of C(4) plant responses to elevated [CO(2)] has been controversial.
• Recent evidence from free-air CO(2) enrichment (FACE) experiments suggests that elevated [CO(2)] does not directly stimulate C(4) photosynthesis.
• Nonetheless, drought stress can be ameliorated at elevated [CO(2)] as a result of lower stomatal conductance and greater inter cellular [CO(2)].
• Therefore, unlike C(3) crops for which there is a direct enhancement of photosynthesis by elevated [CO(2)], C(4) crops will only benefit from elevated [CO(2)] in times and places of drought stress.
• Current projections of future crop yields have assumed that rising [CO(2)] will directly enhance photosynthesis in all situations and, therefore, are likely to be overly optimistic.  
• Additional experiments are needed to evaluate the extent to which amelioration of drought stress by elevated [CO(2)] will improve C(4) crop yields for food and fuel over the range of C(4) crop growing conditions and genotypes.