The role of auxin and ethylene in adventitious root formation in Arabidopsis and tomato

Adventitious roots emerge from aerial plant tissues. Although important for clonal propagation of commercially important crop species, few studies have explored the mechanisms driving the development of these roots. This thesis research explored the hormonal controls and molecular mechanisms of adventitious root formation in Arabidopsis thaliana (Arabidopsis) and Solanum lycopersicum (tomato). Removal of the hypocotyl base and root from Arabidopsis seedlings enhanced the frequency of adventitious root formation. ACC treatment and mutations that cause enhanced ethylene synthesis reduced adventitious root formation in Arabidopsis, but enhanced adventitious root formation in tomato, with opposite effects found in ethylene insensitive mutations. These results are consistent with ethylene oppositely regulating adventitious root formation in these two species, while auxin has a similar stimulatory effect on adventitious root formation in both. Root excision increases both adventitious root formation and auxin transport. Additionally, local increases in auxin induced reporter expression after excision precede adventitious root formation and predict the position of root formation. These results indicate that local auxin accumulation due to changing transport may drive adventitious root formation. Moreover, the auxin transport proteins ABCB19 and PIN1, are required for efficient adventitious root formation. Transcript levels of PIN1 increased with root excision in hypocotyls, while neither ABCB19 transcripts nor pABCB19:GFP fluorescence was found to change. In contrast, pABCB19

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2010

Author dc:creator

• Sukumar, Poornima

• Auxin

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10339/14894

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/14894