Overproduction of Cytokinins in Petunia Flowers Transformed with PSAG12-IPT Delays Corolla Senescence and Decreases Sensitivity to Ethylene

Overproduction of Cytokinins in Petunia Flowers Transformed with PSAG12-IPT Delays Corolla... Plant senescence is regulated by a coordinated genetic program mediated in part by changes in ethylene, abscisic acid (ABA), and cytokinin content. Transgenic plants with delayed senescence are useful for studying interactions between these signaling mechanisms. Expression of ipt , a cytokinin biosynthetic gene from Agrobacterium tumefaciens , under the control of the promoter from a senescence-associated gene (SAG12) has been one approach used to delay senescence. We transformed petunia ( Petunia x hybrida cv V26) with P SAG12 -IPT. Two independently transformed lines with extended flower longevity (I-1-7-22 and I-3-18-34) were used to study the effects of elevated cytokinin content on ethylene synthesis and sensitivity and ABA accumulation in petunia corollas. Floral senescence in these lines was delayed 6 to 10 d relative to wild-type (WT) flowers. Ipt transcripts increased in abundance after pollination and were accompanied by increased cytokinin accumulation. Endogenous ethylene production was induced by pollination in both WT and IPT corollas, but this increase was delayed in IPT flowers. Flowers from IPT plants were less sensitive to exogenous ethylene and required longer treatment times to induce endogenous ethylene production, corolla senescence, and up-regulation of the senescence-related Cys protease phcp1 . Accumulation of ABA, another hormone regulating flower senescence, was significantly greater in WT corollas, confirming that floral senescence was delayed in IPT plants. These results extend our understanding of the hormone interactions that regulate flower senescence and provide a means of increasing flower longevity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

Overproduction of Cytokinins in Petunia Flowers Transformed with PSAG12-IPT Delays Corolla Senescence and Decreases Sensitivity to Ethylene

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Publisher
American Society of Plant Biologist
Copyright
Copyright © 2015 by the American Society of Plant Biologists
ISSN
1532-2548
eISSN
0032-0889
D.O.I.
10.1104/pp.103.023945
Publisher site
See Article on Publisher Site

Abstract

Plant senescence is regulated by a coordinated genetic program mediated in part by changes in ethylene, abscisic acid (ABA), and cytokinin content. Transgenic plants with delayed senescence are useful for studying interactions between these signaling mechanisms. Expression of ipt , a cytokinin biosynthetic gene from Agrobacterium tumefaciens , under the control of the promoter from a senescence-associated gene (SAG12) has been one approach used to delay senescence. We transformed petunia ( Petunia x hybrida cv V26) with P SAG12 -IPT. Two independently transformed lines with extended flower longevity (I-1-7-22 and I-3-18-34) were used to study the effects of elevated cytokinin content on ethylene synthesis and sensitivity and ABA accumulation in petunia corollas. Floral senescence in these lines was delayed 6 to 10 d relative to wild-type (WT) flowers. Ipt transcripts increased in abundance after pollination and were accompanied by increased cytokinin accumulation. Endogenous ethylene production was induced by pollination in both WT and IPT corollas, but this increase was delayed in IPT flowers. Flowers from IPT plants were less sensitive to exogenous ethylene and required longer treatment times to induce endogenous ethylene production, corolla senescence, and up-regulation of the senescence-related Cys protease phcp1 . Accumulation of ABA, another hormone regulating flower senescence, was significantly greater in WT corollas, confirming that floral senescence was delayed in IPT plants. These results extend our understanding of the hormone interactions that regulate flower senescence and provide a means of increasing flower longevity.

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