ACHENE GERMINATION OF ‘UBERLÂNDIA 10,000’, A NEW LETTUCE CULTIVAR RICH IN VITAMIN A

Resumo

‘Uberlândia 10,000’ is a new cultivar developed as an important source of vitamin A, with primary dormancy in the 9th generation of achenes. Thus, the purposes of this study were to evaluate the germination and emergence processes and to compare the polypeptide profile of the endosperm of this cultivar with the ‘Grand Rapids’. Achenes of the 8th generation are indifferent to light, losing this characteristic with age. The germinability of these achenes decreased with age from 97% (20 months) to 45.8% (38 months) and the germination process became slow and asynchronous. The best sowing depth was 1 cm (85% of emergence). Achenes of the 9th generation are photoblastic, with slower and more asynchronous germination in relation to that of the 8th generation. Seedling growth inside the intact endosperm suggests that this reserve tissue has high elasticity. The polypeptide profiles of both ‘Uberlândia 10,000’ and ‘Grand Rapids’ endosperm (SDS-PAGE technique) were similar, but with higher concentrations in the latter. p41 probably is one endo-β-mannanase, because it appeared in the endosperm of both cultivars close to the moment of the embryo protrusion. These results gave rise to new questions. Is p41 an endo-β-mannanase? Is it in the active form and in the appropriate quantity to allow the hydrolysis of the endosperm? Is it related to the germination process of this cultivar?