Effects of ethylene, cytokinin, and physical treatments on BoPaO gene expression of harvested broccoli

GÓMEZ LOBATO, MARÍA EUGENIA; CIVELLO, MARCOS; MARTÍNEZ, GUSTAVO

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE

JOHN WILEY & SONS LTD

Año: 2012 vol. 92 p. 151 - 158

0022-5142

Background: Broccoli is a highly perishable vegetable that shows an enhanced postharvest senescence and intense de-greening caused by chlorophyll degradation. One of the key steps of chlorophyll catabolism is the opening of chlorophyll tretrapyrrole catalyzed by Pheophorbide a oxygenase (PaO). In this work, we characterized the expression of a gene encoding a putative PaO under several chemical and physical treatments.Results: We cloned a fragment of a gene encoding a PaO from broccoli (BoPaO). The expression of BoPaO showed an important increment during postharvest senescence, in correlation with chlorophyll degradation. Furthermore, broccoli heads were treated with the hormones cytokinin and ethylene. Cytokinin delayed the increment of BoPaO expression whereas ethylene accelerated the process. Also, several postharvest treatments were applied in order to evaluate their effect on BoPaO expression. Samples treated with modified atmosphere, hot air, UV-C or white lights showed a delay in chlorophyll degradation and degreening. In most cases, the treatments also delayed the increment of BoPaO expression during senescence.Conclusion: A close correlation between chlorophyll degradation and expression of BoPaO was found during broccoli senescence. This relationship was corroborated in samples treated with different hormonal and physical applications.