H. Nonogaki et Y. Morohashi, Temporal and spatial pattern of the development of endo-beta-mannanase activity in germinating and germinated lettuce seeds, J EXP BOT, 50(337), 1999, pp. 1307-1313
The development of endo-beta-mannanase activity and the changes in the enzy
me content were followed during and after germination of lettuce seeds. End
o-beta-mannanase activity was not detected before germination. It began to
develop immediately after radicle protrusion. The development of the enzyme
activity occurred specifically in the endosperm tissue and activity staini
ng of native-PAGE gels revealed that three isoforms of the enzyme are prese
nt. SDS-denatured polypeptides of these isoforms were all recognized by ant
i-tomato-endo-beta-mannanase antibodies. Molecular masses of these polypept
ides seemed to be very close to each other and were estimated to be about 3
9 kDa. The pattern of changes in the activity of endo-beta-mannanase in the
endosperm during seedling growth was parallel to that of changes in the co
ntent of the enzyme protein, indicating that the increase in enzyme activit
y is due to the accumulation of the enzyme protein. Tissue prints showed th
at the activity initially developed in the endosperm region near the embryo
nic axis and then spread over the endosperm tissue. These results indicate
that endo-beta-mannanase production in lettuce endosperm is carried out in
a spatially and temporally regulated manner.