Ethylene Induced Flower Opening, Expression of Receptor Genes, and Antioxidant Defensive Responses in Cut Roses

Abstract

The present research aimed to investigate the effect of ethylene on the physiological and molecular responses of the cut roses, Rosa hybrida L. Two cut rose cultivars (‘Amada +’ and ‘Brillante’) with different ethylene sensitivity were treated by 10 ppm exogenous ethylene for 24 h under identical vase life room conditions at partially open stage. The cultivars were then examined at both partially and fully open stage by gas chromatography, UV/Vis spectroscopy, and qRT-PCR. The cultivar with high sensitivity had lower total protein contents and showed higher ethylene production and antioxidant activity. Either exogenously applied ethylene or endogenously produced one resulted in increased antioxidant activity and decreased total protein contents. This observation is possibly because of enhanced free radical generation and protease activation with ethylene-induced flower opening and senescence. The qRT-PCR analysis showed a significant increase in the expression of ethylene signal transduction genes (RhETR1,3 and RhCTR1,2) of the treated cultivars with high sensitivity at commercial stage. However, there was a significant up-regulation of the RhETR1,3 genes in the cultivars with low sensitivity at fully-open stage. The ethylene induced responses were found highly dependent on the cultivar ability in both ethylene synthesis and perception.