ARS | Publication request: The effects of benzyladenine and meta-topolin on in vitro shoot regeneration of sweet orange.

Submitted to: ARPN Journal of Agricultural and Biological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 30, 2010
Publication Date: April 13, 2011
Citation: Niedz, R.P., Evens, T.J. 2011. The effects of benzyladenine and meta-topolin on in vitro shoot regeneration of sweet orange. ARPN Journal of Agricultural and Biological Science. 6:64-73.

Interpretive Summary: Plant tissue culture is essential for applying certain techniques to enhance plant variety development. One type of tissue culture is the regeneration of shoots from stem pieces, an important method required to genetically engineer a plant. In this study, we compared the effects of the two plant growth regulators benzyladenine purine (BA) and meta-topolin (mT) on shoot regeneration from stem pieces of Hamlin sweet orange, the most widely grown commercial sweet orange of Florida. BA is the standard plant growth regulator used in citrus tissue culture. mT is a closely related molecule isolated from poplar. Because small alterations in chemical structures can sometimes have large effects, we compared the ability of these two growth regulators to produce shoots from isolated stem pieces. We found out two things about how these two compounds affect shoot regeneration in citrus; first, the two compounds act independently and do not interact; and, two, the amount of BA in the medium is the primary factor that affects shoot regeneration in Hamlin.

Technical Abstract: The effects of 6-benzyladeninepurine (BA) and meta-topolin (mT) on shoot quality, numbers of epicotyl explants producing buds and/or shoots, and the number of shoots greater than 2 mm from Hamlin sweet orange (Citrus sinensis (L.) Osbeck) epicotyl explants were determined. The experiment was designed as a mixture-amount. The two mixture components, BA and mT were varied proportionally from 0 BA:1 mT to 1 BA:0 mT and the amount of total cytokinin varied from 1 to 50 µM. The polynomial response models developed for each of the three measured responses were highly significant (p < 0.0001) and allowed for the accurate determination of the proportional and amount effects of these two cytokinins on the measured responses including, 1) proportional effects were either not detected (number of explants w/ shoots/buds and number shoots > 2 mm) or were statistically significant but had minimal biological effect (overall quality) and, 2) the amount of cytokinin (BA or mT) in the medium was the primary determinant for all three responses.