PJB-2022-220
The effects of plant hormones on lettuce seed germination under far-red light stress and its relationship with cell wall degrading enzymes
Juan Liang
Abstract
In this study, we used lettuce seeds as experimental materials to study the effect of plant hormones on seed germination under far-red light stress, as well as the relationship between seed germination and cell wall degrading enzyme activities. With this study, we aimed to explore the physiological mechanism of exogenous hormones promoting seed germination under light stress, and provide a scientific basis for the application of hormones in agricultural production. Our results showed that, the germination of lettuce seeds was significantly inhibited by heat. Under sub-optimal temperature (>21℃), red light promoted seed germination, while far-red light inhibited seed germination. Under far-red light stress (light intensity of 0.1 μmol•m-2•s-1, photoperiod of 14 h light/10 h dark), applying exogenous hormone GA3 or FL (ABA inhibitor) could promote the germination of lettuce seeds, and the combination of both further increased the seed germination rate; on the other hand, ABA and PAC (GA inhibitor) inhibited the germination of lettuce seeds. Further analysis of the changes in cell wall degrading enzyme activity during seed germination showed that, the activities of α-galactosidase and endo-β-mannanase were significantly increased in lettuce seeds under far-red light stress after FL and GA3 treatments, and endo-β-mannanase increased more significantly; with the combined treatment of GA3 and FL, the two enzymes showed the highest activities, suggesting that the germination rate of lettuce seeds was positively correlated with the activity of cell wall degrading enzymes. This result indicated that FL and GA3 could promote the germination of lettuce seeds under far-red light stress by increasing the activities of α-galactosidase and endo-β-mannanase, which in turn weakened the endosperm and promoted germination.
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