Pollen viability is a critical factor in ensuring fertilization and, ultimately, crop yields. However, wheat pollen is particularly vulnerable to heat stress, which can lead to abnormal pollen development, poor tube growth, and diminished fertilization. Despite its importance, current methods for screening heat tolerance in pollen are time-consuming and labor-intensive, often requiring large spaces and days of testing.
The newly developed protocol offers a rapid and reliable alternative. Using gradient PCR machines to test pollen viability across a wide range of temperatures, the method allows for precise measurement of heat tolerance in pollen samples in just a few hours. The ability to assess multiple temperatures simultaneously streamlines the process, providing critical insights into the effects of temperature stress on wheat pollen in a fraction of the time required by traditional methods.
The study, led by Prof. Zhou, involved exposing wheat pollens to temperatures ranging from 21.9 to 47°C under a 4-hour incubation in liquid medium. Subsequently, pollen germination rates and tube growth were examined under a microscope. "The gradient PCR machine allowed us to test multiple temperatures at once, which was a convenient method in terms of efficiency," said Dr. Zhao (leading author). "Not only did it speed up the process, but it also provided a wide temperature range to test pollen viabilities under heat stress."
Although the protocol was developed for wheat, it has the potential to be applied to a wide range of crops. The research team validated their method on barley pollen, resulting in an optimal temperature of 27.2°C which was slightly lower than wheat pollen. The study also found a strong correlation between pollen size and heat tolerance, with larger pollen grains exhibiting greater viability under high temperatures. This discovery could further help identify traits linked to heat tolerance, providing additional targets of selection in breeding programs.
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