Maternal effect on thermotolerance in lettuce seeds

Abstract The objective of this work was to evaluate the occurrence of the maternal effect on thermotolerance in lettuce (Lactuca sativa) seeds, as well as to find an enzymatic marker for this trait in lettuce seedlings. Seeds from the Everglades thermotolerant cultivar, the Verônica susceptible cultivar, and their reciprocal hybrids were used. For each cultivar and reciprocal hybrid, germination percentage and vigor (germination speed index) tests were carried out at 20 and 32°C. Thermotolerance was defined as the capacity to germinate at 32°C. To obtain markers that could be associated with thermotolerance, enzymatic tests were performed. The bands of the electrophoretic enzymatic extracts were quantified using the ImageJ software. The hybrids behaved similarly to their female genitors. When cultivar Verônica was the female genitor, hybrid seeds did not germinate at high temperatures and showed a lower expression of the esterase enzyme. However, when the female genitor was the Everglades cultivar, hybrids showed a high germination at high temperatures and a greater esterase expression. Therefore, there is a maternal effect on tolerance to thermoinhibition in lettuce seeds, and the esterase enzyme can be used as a selective marker to identify homozygous progenies for this trait.