Heat stress induced ethylene production in developing wheat grains induces kernel abortion and increased maturation in a susceptible cultivar

In this work we present evidence that the heat stress induced kernel abortion and suppression of grain maturation in a representative heat susceptible hard red winter wheat (Triticum aestivum L.) cultivar is regulated by heat stress induced ethylene production. Exposure to heat stress (38 °C) during early kernel development (10 DAP) resulted in a 6-fold increase in ethylene production in developing kernels of the heat susceptible hard red winter wheat cultivar ‘Karl 92’. A similar 7-fold increase in ethylene production in embryos and 12-fold increase in ethylene production in the flag leaf of heat stressed plants of ‘Karl 92’ was also found. In contrast, no change in ethylene production was observed in the heat tolerant hard white spring wheat cultivar ‘Halberd’. In an effort to link the heat stress induced ethylene production to the observed increase in kernel abortion and reduced kernel weight in the heat susceptible ‘Karl 92’, plants were treated with the ethylene receptor inhibitor 1-methylcyclopropane (1-MCP) prior to exposure to heat stress. Inhibiting ethylene perception in the heat susceptible ‘Karl 92’ in this manner blocked heat stress induced kernel abortion and reduction in kernel weight and demonstrated a clear link between ethylene in regulating susceptibility to heat stress or perception of high temperatures as a timing signal for transitioning to developmental arrest and senescence in certain wheat genotype classes.