Reportedly, scientists from Yale University have recently discovered that a common weed named “Portulaca oleracea”, or simply purslane, may help in the development of drought-resistant crops. This study provides valuable insights into the fight against climate change. Using a unique type of photosynthesis, this weed not only survives in droughts but also remains highly productive.
Introduction to Purslane
Purslane has evolved to become both highly productive and drought-resistant, two qualities that are usually seen as contradictory in nature. This plant is primarily annual, but can also be perennial in tropical climates. Its stems are glabrous, fleshy, purplish-red to green, arising from a taproot, often prostrate, forming mats.
The plant typically grows in temperate and subtropical regions, extending into tropical and high-latitude areas. It can be found in various environments such as fields, gardens, vineyards, beaches, salt marshes, waste areas, eroded slopes, bluffs, riverbanks, and even driveways. However, it competes with many field crops for resources, particularly with herbaceous species that are germinating or growing simultaneously.
Photosynthesis Adaptations in Purslane
Plants have independently evolved various mechanisms to enhance photosynthesis. This process allows green plants to synthesize nutrients from carbon dioxide and water using sunlight. Certain plants like corn and sugarcane have evolved C4 photosynthesis, allowing them to thrive under high temperatures. Similarly, succulents like cacti and agaves possess CAM photosynthesis, which aids their survival in desert-like conditions or areas with scarce water. The study noted that the purslane unifies these two types of photosynthesis, giving it an unusual level of protection during droughts.
The Different Types of Photosynthesis: C3, C4, and CAM
The C3 Cycle, also known as the Calvin Cycle, is a cyclic reaction process occurring in the dark phase of photosynthesis. This process converts carbon dioxide into sugars, making it a method of carbon fixation. It was first observed by Melvin Calvin in unicellular green algae, Chlorella, for which he was awarded the Nobel Prize in 1961. Some examples of C3 plants include wheat, oats, rice, and sunflower.
C4 plants exhibit a different leaf anatomy. These plants have larger chloroplasts that lack grana and contain starch grains, surrounded by a bundle sheath of larger parenchymatous cells in their leaves. The mesophyll cells in these plants, on the other hand, have smaller chloroplasts with grana. Maize, sugarcane, and amaranthus are some examples of C4 plants.
The CAM Cycle is another type of photosynthesis that occurs in the dark phase. It is a carbon dioxide fixation process where malic acid is the first product. CAM plants are usually succulents that grow under extremely arid conditions. They have leaves that are succulent or fleshy, and their stomata remain open during the night and close during the day. Examples of CAM plants include pineapple and snake plant.
Final Thoughts
The study of how purslane combines both C4 and CAM photosynthesis, thus managing to thrive and stay productive under tough conditions, offers great promise for agricultural advancements. As we continue to fight against climate change and its consequences, this could be an important step towards developing more resilient crops.