Bleached protoplasts can be used in protoplast fusion experiments to label one of the partners so that heterokaryons can be identified. Protoplasts isolated from plants which were white because they were grown in low concentrations of Sandoz herbicides have been regenerated to plants (Puite et al., 1986; Uhrig, 1981).
Tomato seeds were surface sterilized and planted in Magenta GA7 boxes containing TM-1 (Shahin, 1985). The boxes were kept in the dark until the seeds had germinated. Seedlings were grown in 150 uEm^-2^sec^-1 from cool-white bulbs at 24 deg. C for 8 days. Shoots were removed and transferred to 10 mls TM-1 with the indicated concentration of herbicide in 15 x 150 mm glass tubes. After 21 days, rooted cuttings were harvested and the white leaf material was weighed. Norflurizon, 80% a.i., (Solicam), or Sandoz 9789 can be used with equal effect. When using the 80% material, we found that 2.5 ppm produced the largest amount of white leaf material (Table 1). The 2.0 rate is recommended because the leaves appeared to be more vigorous. Protoplasts could be isolated from bleached leaf material according to the procedure of Shahin (1985).
Table 1: Yields of white leaf material from rooted tomato cuttings grown in norflurazon
_______________________________________ Norflurazon Mean leaf SE concentration, material mean ppm a.i. gm _______________________________________ 1.0 0.041 0.0060 1.5 0.073 0.0096 2.0 0.135 0.0196 2.5 0.136 0.1711 3.0 0.096 0.0072 0 0.341* 0.242 _______________________________________a.i.: active ingredients
* green leaf material from control
Literature cited:
Puite, K.J., S. Roest, and L.P. Pijnacker. 1986. Somatic hybrid potato plants after electrofusion of diploid Solanum tuberosum and Solanum phureja. Plant Cell Reports 5:262-265
Shahin, E. A. 1985. Totipotency of tomato protoplasts. Theor. Appl. Genet. 69:235-240.
Uhrig, H. 1981. Regeneration of protoplasts of dihaploid potato plants bleached by a herbicide (SAN 6706). Mol. Gen. Genet. 181:403-405.