Development of galactomannan‐hydrolyzing activity in the micropylar endosperm tip of tomato seed prior to germination

Development of galactomannan‐hydrolyzing activity, that is involved in the weakening of the mechanical restraint of the endosperm, was followed at pre‐germinative stages in tomato (Lycopersicon esculentum) seed. Prior to germination the activity developed exclusively in the endosperm portion just adjacent to the radicle tip. In other parts of the endosperm, the activity developed only after germination occurred. Under the conditions where germination was suppressed (far‐red light‐ or ABA‐treatment). no activity was detected in the endosperm at the pre‐germinative stages. Under the conditions where the inhibition of germination was alleviated (far‐red + red or ABA + GA3), the activity developed prior to germination in the endosperm part in front of the radicle tip. Thus, a clear parallel relationship was observed between germinability of the seed and the pre‐germinative development of activity in the part of the endosperm portion adjacent to the radicle tip.