Submitted to: Plant and Molecular Biology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2011
Publication Date: 4/16/2011
Citation: Tyagi, N., Dahleen, L.S. 2011. Timing of Ethylene Modification Is Critical For Regeneration In Barley. Plant and Molecular Biology and Biotechnology. 4:47-55. Interpretive Summary: Growing plant cells in tissue culture is a common method used for cloning of multiple plants from a single plant, and to insert new genes into plants. These systems require green plant regeneration from these cultured tissues. In barley, most of the varieties of interest do not regenerate many plants. The plant hormone ethylene was shown to affect how many plants were formed. When ethylene production was inhibited for one week during certain times of tissue culture, the number of plants regenerated was increased in one barley variety but not in a second variety. When ethylene production was increased in the first variety, plant regeneration decreased. Identifying the times when ethylene production needs to be reduced can be used to improve green plant regeneration from specific barley varieties, making those varieties useable for experiments that require tissue culture.
Technical Abstract: : The plant hormone ethylene is important for higher rates of callus formation and green plant regeneration. Ethylene can have positive or negative effects on these traits depending on the genotype, type of explant and stage of application. Therefore, the effects of both ethylene precursors and inhibitors have been tested. l-aminocyclopropane-l-carboxylic acid (ACC) and aminoethoxyvinyl-glycine (AVG) were used to determine the optimal timing of application for ethylene control to improve regeneration in barley (Hordeum vulgare L.) cultivars Golden Promise and Morex. One-week AVG (5 µM) and ACC (100 µM) treatments were applied in two phases covering maintenance and regeneration (wks 5-14) of a well defined protocol. Only the AVG treatments were studied in Golden Promise. Ten-week AVG treatments (5 µM) were also tested in wks 5-14 to determine the effect of total inhibition of ethylene synthesis in both cultivars. The 10-week treatment generally reduced ethylene production in both cultivars but had limited and insignificant effects on regeneration in both cultivars. One-week AVG treatments significantly reduced ethylene production in both cultivars and significantly improved green plant regeneration in Morex, when applied in wks 11-13. In Golden Promise, the AVG treatments did not show significant increase in regeneration. ACC treatment in Morex led to a significant increase in the amount of ethylene produced but did not significantly affect the regeneration rates. The regeneration rates were strongly affected by the environment of the donor plant. These results indicate that the timing of application of chemicals is critical for controlling ethylene synthesis in barley tissue cultures and depends on the physiological stage of the explants. Manipulation of ethylene production at the appropriate times can induce significant increases in regeneration from recalcitrant barley cultivars.