Cool buds
Sometimes plants are too hot. Especially pollen development is heat sensitive. But, as Dutch researchers show in a Preprint, plants have found a way around.
When pollen develop during a heatwave they are often not viable. With as result: lower fertility. But fortunately plants have found a solution, they cool their flower buds during hot weather. The researchers studied how the plant does this, and if it works.
First they measured the temperature inside and outside tomato flower buds. They observed that when the outside temperature gets above 26°C the temperature inside the flower bud does not keep up. This temperature difference increased to 2 degrees when the outside temperature got to 34°C.
To find out how the plant keeps their buds cool, the researchers closed of the flower bud stomata. This resulted in a smaller temperature difference between the inside and outside of the flower buds. The confirmation that a plant cools its flower buds via its stomata came from a tomato plant that could not close its stomata. The buds of these plants were even cooler during hot conditions that that of plants that could close their stomata. In addition, the plants that could not close their stomata were also more fertile during a heatwave.
Tomato plants with cooler bust grow more tomato’s
Subsequently the researchers found a tomato variety that has natural better flower bud cooling. They noticed that this cool bud variant had a higher heat tolerance. Where his not so cool brothers got infertile at 32C, this cool bud variant could hold it out till 33C.
The cool bud variant also turned out to cool its flower buds by opening its stomata. But, importantly, it could do this independently from the stomata in its leaves.
That this also is an advantage in real life the researchers found out while growing the cool bud tomato variant in Spain during a heatwave. The cool bud variant grew more tomato’s than its not so cool brothers.
Literature
Martijn J. Jansen, Stuart Y. Jansma, Klaske M. Kuipers, Wim H. Vriezen, Frank F. Millenaar, Teresa Montoro, Carolien G.F. de Kovel, Fred A. van Eeuwijk, Eric J.W. Visser, Ivo Rieu (2024) Flower bud cooling protects pollen development and improves fertility during heatwaves. bioRxiv 2024.08.18.608441; doi: https://doi.org/10.1101/2024.08.18.608441
Plant en Zo 