Common buckwheat (Fagopyrum esculentum Moench) is a valuable crop plant with cereal-like seed chemical composition; however, it is susceptible to thermal stress. The aim of the study was to determine whether heat-shock proteins HSP-90 and HSP-70 can protect common buckwheat against thermal stress during development of microspores and embryo sacs. The study was performed on two accessions of common buckwheat, Panda and PA15, which differed in their tolerance to thermal stress. Accumulation of these proteins was determined in buds, open and wilted flowers, and donor leaves of plants grown at 20°C (control) and 30°C (thermal stress). Photochemical efficiency of donor leaves, closest to the inflorescences, based on chlorophyll a fluorescence (ChlF) was also analysed. All plants demonstrated higher values of ChlF at 30°C than at 20°C, which suggests that this 30°C temperature is more conducive to their vegetative growth. Pollen grains of both accessions demonstrated normal development at 30°C, whereas embryo sacs showed many developmental disturbances. Panda was more sensitive to thermal stress than PA15, as manifested in a higher percentage of degenerated embryo sacs at the flower bud phase. Moreover, a decrease in both HSPs in the studied organs of Panda was found relative to the control. At 30°C, both accessions accumulated more HSP-70 than HSP-90. These results suggest that, under heat stress, HSP-70 plays a protective role for flowers of common buckwheat. The analyses indicated that the donor leaf closest to the flower cluster may be a reliable indicator of temperature sensitivity in buckwheat flowers.

普通荞麦（Fagopyrum esculentum Moench）是一种有价值的农作物，具有类似于谷物的种子化学成分。但是，它容易受到热应力的影响。该研究的目的是确定在小孢子和胚囊发育过程中，热休克蛋白HSP-90和HSP-70是否可以保护普通荞麦免受热胁迫。这项研究是针对两种常见的荞麦（熊猫和PA15）进行的，它们对热胁迫的耐受性不同。确定了在20°C（对照）和30°C（热胁迫）下生长的植物的芽，开放和枯萎的花朵以及供体叶片中这些蛋白质的积累。基于叶绿素a的最接近花序的供体叶片的光化学效率还分析了荧光（ChlF）。与20°C相比，所有植物在30°C时均显示更高的ChlF值，这表明30°C的温度更有利于其营养生长。两种花粉的花粉粒均在30°C下发育正常，而胚囊显示出许多发育障碍。熊猫比PA15对热应激更敏感，这表现为在花蕾期退化的胚囊的百分比更高。此外，在熊猫的研究器官中发现两种HSP均相对于对照有所降低。在30°C时，两个种质积累的HSP-70比HSP-90多。这些结果表明，在热胁迫下，HSP-70对普通荞麦的花具有保护作用。