Effect of a pretreatment of seed coats with a low-osmolality solution on subsequent [14C] sucrose transport into attached empty ovules of pea

This paper discusses the question as to whether or not the seed coat tissues can‘adapt’to a treatment with a solution containing a low osmoticum concentration, representing an environment which is sub-optimal for assimilate transport into attached surgically modified ovules. Before the start of a pulse-labelling procedure, in experiments on [¹⁴C] sucrose transport into fruits of pea (Pisum sativum) with four empty ovules, two empty ovules were filled with a low-osmolality solution (a 200 mol m^?3 mannitol medium or a solution without mannitol) and the other two ovules were filled with a 400 mol m^?3 mannitol medium. Pretreatment with a low-osmolality medium, during a period of 2–3 h, enhanced subsequent transport of [¹⁴C] sucrose into empty ovules filled with a low-osmolality medium, in comparison with [¹⁴C] sucrose transport into empty ovules filled with a 400mol m^?3 mannitol medium during the pretreatment period. This partial recovery of sink strength of attached empty ovules can be explained as the result of a stimulation of solute efflux from seed coat cells at high cell turgor.