Endo-?-mannanase and superoxide dismutase as enzymatic markers for lettuce seeds thermotolerance

At higher temperatures, lettuce seeds may not germinate, resulting in problems for crop establishment in the field and production. This study aimed to evaluate the maternal effect for thermotolerance on lettuce seeds and find enzymatic markers. We used the thermoinhibition tolerant cultivar 'Everglades', the sensitive 'Veronica', their reciprocal hybrids, F1 and F2 generation. Seeds were submitted to germination and enzymatic tests (catalase, superoxide dismutase, ascorbate peroxidase, and endo-beta-mannanase). Germination (first and final counting) and speed index were compared through Tukey's test. 'Everglades' and its reciprocal hybrids, have not been influenced by temperature regarding germination compared to the other treatments. Also, the maternal effect was observed for the F1 generation. Higher temperatures interfere with the activity of all enzymes evaluated, consequently in the physiological parameters. However, superoxide dismutase and endo-beta-mannanase have shown direct and more expressive correlation with changes on the physiological parameters compared to the other enzymes. Thus, it is possible to conclude that those enzymes can be used as markers for thermotolerant genotype selection.

Automated summary

At higher temperatures, lettuce seeds may have difficulty germinating, impacting crop establishment and production. This study aimed to assess the maternal effect on thermotolerance in lettuce seeds and identify enzymatic markers. 'Everglades' and its reciprocal hybrids showed no influence on germination compared to other treatments. Higher temperatures affected the activity of all enzymes, but superoxide dismutase and endo-beta-mannanase had a stronger correlation with physiological changes. These enzymes can be used as markers for selecting thermotolerant genotypes.