GROWTH AND OSMOTIC ADJUSTMENT OF CULTURED SUSPENSION CELLS FROM ALTERNANTHERA-PHILOXEROIDES (MART) GRISEB AFTER AN ABRUPT INCREASE IN SALINITY

We have developed a cell suspension culture from alligator weed (Alternanthera philoxeroides [Mart.] Griseb), a C3 member of the Amaranthaceae. Intact plants of alligator weed can grow at 400 mol m-3 NaCl. Growth of alligator weed suspensions was compared to growth of tobacco (Nicotiana tabacum L. cv. Wisconsin 38) suspensions after subculture to 200 mol m-3 NaCl. Fresh weight and cell density of salt-treated alligator weed suspensions more than doubled by 7 d after subculture, but the fresh weight of salt-treated tobacco suspensions did not double during the 21 d experiment. Correspondingly, cell viability dropped from about 90% to 77% in alligator weed and to 41% in tobacco, at 1 d after subculture to 200 mol m-3 NaCl. The symplastic volume of alligator weed cells declined 36% by 2 h after subculture to 200 mol m-3 NaCl, but cell contents became iso-osmotic with the media at this point. Between 2 h and 6 h there was a further decrease in osmotic potential, an increase in turgor potential and a partial recovery of symplastic volume. Turgor potential was similar to that in control cells by 24 h, indicating significant osmotic adjustment. Turgor potentials remained similar in both treatments from 24 h through 21 d but the average symplastic volume of salt-treated cells was 11% less than in control cells. Therefore, alligator weed suspension cells exhibit a rapid recovery of water balance and cell growth after an abrupt and substantial increase in salinity.