**2.4 Heat tolerance of tomato pollen and possibility of gametophytic selection for resistance to temperature stress**

It is important in tomato breeding, especially for greenhouse cultivation, to keep in mind the heat resistance of pollen and to develop varieties and hybrids with this property. There are also known studies by G.I. Tarakanov et al. [28], who, taking into account the unequal value of different pollen grains in terms of heat resistance, used the most resistant gametes to obtain offspring. As a result of single and double selection, plants were raised that significantly exceeded the original specimen in terms of fruit set under conditions of elevated temperatures. Based on the available literature data, we can say that in tomatoes in the phase of mature pollen grain there is an opportunity for selection at the haploid level in order to change the tolerance to temperature stress of sporophytic offspring [28, 29].

Microgametophytic selection requires an answer to the question of the duration and magnitude of the effect on pollen in order to ensure both a sufficient strength of selection and the formation of an acceptable number of seeds in fruits. The material for the study was pollen of interspecific tomato hybrids obtained from the crossing of the Mo 500 mutant line with the wild species *Lycopersicum minutum* Rick and *Solanum pennellii* Corr. The pollen was heated in a thermostat at 58°C for 1, 2, 3, 6, and 12 h.
