| Ethylene is involved in many different physiological processes in plants, including flower initiation, as well as flower senescence. The role of ethylene in flower senescence, a problem for the cut flower industry, is of interest in snapdragon. Ethylene tolerance has been induced in such plants as Arabidopsis, cut carnations, petunia and tomato with the use of chemical mutagens. In order to investigate this approach in snapdragon, 2,000 seeds of a proprietary line OAK564 were treated with 0.50, 0.75, or 1.0% EMS for 10 h and allowed to germinate. M1 plants were self-pollinated to generate M2 seeds that were screened for seedling ethylene insensitivity.; A tissue culture screen for ethylene tolerance utilizing ACC was optimized for a snapdragon inbred line, OAK564. Moreover, 40,000 EMS mutagenized snapdragon seeds were also screened for ethylene insensitivity. From this, a total of 231 putative ethylene mutants were recovered. Putative ethylene tolerant M 2 plants were grown, and selfed seeds were collected. These M3 seeds were screened with ACC to reassess their tolerance to ethylene. Responses varied from complete ethylene tolerance to ethylene sensitivity. Characterization of mutant lines included investigation of developmental regulation of vegetative and floral tissues in using five ACS and two ETR genes. Gene expression patterns were also investigated when floral spikes were exposed to 250 muM ACC either with or without pre-treatment with 1-MCP. Additional characterization included characteristics of rooting, gravitropism, ethylene tolerance, and vase-life studies using putative ethylene mutants. Ethylene mutants displayed varied responses for all evaluations, with some lines exhibiting enhanced rooting, gravitropism, floral fitness, ethylene tolerance, and vase-life when compared to the inbred OAK564. Overall, a mutagenesis approach to increase ethylene tolerance in cut snapdragon flowers was successful in generating mutants altered at different genetic loci and exhibiting enhanced traits including, vase-life, gravitropism, and rooting ability. |
