Botanist's Lens: Ethylene or ABA, who is going to be more active this fall?
- Meenal Harankhedkar, Director of Horticulture
- Oct 11, 2019
- 2 min read
Slowly but surely, many leaves have started to show off their fall colors. The pigments in the leaves that are responsible for the beautiful warm colors are anthocyanins, carotenoids or xanthophyll. As the primary pigment, chlorophyll fades and the green color diminishes, other pretty fall colors start coming through. There is ample information and research on plant pigments responsible for fall colors. But there is little information on the anatomical and physiological changes and what actually happens inside the plants as the leaves start falling form the tree.
Ethylene (plant hormone responsible for ripening and senescence), Abscisic acid -ABA (stress hormone), and Auxin (growth hormone) all play a symphony and cause 'Abscission- falling/separation of leaf tissue' from the plant. What is commonly seen as leaves falling from the tree, is really abscission of a leaf tissue at the base that makes the leaf drop. When Abscission happens, an abscission zone is developed at the base of the petiole (stem of leaf). But why and how is this abscission layer formed?
Here is a simple way to understand it: when plants are stressed, they go from full growth stage into a survival mode. When the plants undergo stress, the stress hormone (ABA) levels rise and the growth hormone (auxin) level that promote cell elongation, reduces. When cell elongation reduces, meaning the plant gets a signal that growth has reduced/stopped in certain parts, the plant gets a signal for senescence (death of tissue) and an abscission layer starts forming. That's when Ethylene levels increase to fasten senescence.
For a long time, abscission was connected with Abscisic acid-ABA, which was thought to be solely responsible for abscission (breaking of leaf from petiole), but research shows that Ethylene is actually responsible for completing senescence. Ethylene acting as a hormone in plants, exists as a gas at trace levels and causes not only abscission, but also fruit ripening and opening of flowers.
"Ethylene has been used in practice since the ancient Egyptians, who would gas figs in order to stimulate ripening. The ancient Chinese would burn incense in closed rooms to enhance the ripening of pears". (https://pages.wustl.edu/ipgsa/ethylene). “Commercial ripening rooms use "catalytic generators" to make ethylene gas from a liquid supply of ethanol. Farmers in Florida would commonly get their crops to ripen in sheds by lighting kerosene lamps, which was originally thought to induce ripening from the heat”. (https://en.m.wikipedia.org/wiki/Ethylene).
Fall colors of leaves are a treat to the senses. It is also a reminder for a seasonal change. What is happening inside the plant is also a change and preparation for a stressful cold period. Plants dropping all their leaves, is a survival mode for plants wherein it is conserving its energy and sending it to the roots and branches instead of the leaves.
It is important to note that senescence is also a natural phase in the life cycle of a plant. With fall colors currently at the brim, Ethylene at trace levels is surely going to be very active in millions of leaves instead of ABA which was originally thought to be leading senescence.
Enjoy the vibrant warm colors of leaves before abscission starts and leaves actually drop down. Here is a good link for fall color prediction map for this year: https://smokymountains.com/fall-foliage-map/
This article offers such a fascinating deep dive into the botanical ballet of autumn! I've always admired fall colors, but understanding the intricate physiological dance between ethylene, ABA, and auxin that leads to abscission truly adds another layer of appreciation. It's particularly insightful to learn that ethylene, not just ABA, ultimately drives senescence, challenging earlier assumptions. This detailed explanation of how plants prepare for winter is truly illuminating. For anyone looking to compile notes or images from informative articles like this, I often find myself using Merge JPG to PDF Online to keep everything organized. Thanks for the great read and the fall color prediction map!
This is a fascinating breakdown of the science behind fall foliage! I've always admired the beauty of autumn leaves, but this article really dives into the intricate physiological changes happening within the plants, particularly the "symphony" of ethylene, ABA, and auxin. It’s insightful to learn that while ABA was once thought to be solely responsible for abscission, ethylene actually plays a more active role in completing senescence, mirroring the ancient practices of using gases to ripen fruits. Understanding this survival mechanism helps appreciate the season even more. For anyone wanting to keep notes on such detailed botanical processes, a tool like Markdown to PDF Converter could be really useful for organizing research!
This is a truly insightful dive into the complex world of plant physiology during autumn! I particularly enjoyed learning about the nuanced roles of ethylene and ABA in abscission. It's fascinating how the long-held belief about ABA's sole responsibility is being refined by research highlighting ethylene's active role in senescence. Understanding these internal processes really adds another layer of appreciation to the beautiful fall colors. For anyone working with digital illustrations of nature, a tool like Converter PNG to SVG could be really useful for preserving the crispness of leaf patterns for various design projects. Thanks for shedding light on the science behind the seasonal spectacle!
This is a truly fascinating dive into the unsung heroes of autumn! I always appreciated the beauty of fall foliage, but understanding the intricate biological dance between ethylene, ABA, and auxin is truly insightful. The clarification that ethylene, not just ABA, is the key player in driving senescence and leaf abscission really sheds light on the process. It's amazing how plants shift into "survival mode," conserving energy for the colder months. It reminds me of how we often present different "versions" of ourselves in varying situations – speaking of which, for anyone curious about making a strong visual impression in their professional or personal life, you might find something like an Attractiveness Test a surprisingly useful tool!
This article offers such a fascinating deep dive into the physiological ballet happening within plants as they prepare for winter! It's enlightening to learn that ethylene, not just ABA, is the key player in orchestrating abscission and those gorgeous fall colors. The historical examples of gas-ripening were particularly interesting. For anyone looking to understand complex topics like this more deeply, extracting information from educational videos can be really helpful. In fact, for breaking down detailed science explanations, I often use YouTube Transcript Generator to get accurate transcripts. It's a great tool for summarizing and studying!