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In this article we will discuss about the antisense RNA in cut flower industry.
Presently, cut flower industry is billion dollar business worldwide and extends trade of worth over 25 billion US dollar per annum. Several major countries particularly Germany, Netherland, TTS share a major chunk of cut flower business and their market turnover reaches 3-5 billion US dollar.
The asthetic beauty of several flowers like tulip, lily, rose, carnation, gerbera provides good access to export business in the international market. Economy of consumers like Thailand, Malaysia and Singapore depending on orchid cut flower business.
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Country – Export value (US $ million)
Holland – 1590
Columbia – 430
Israel – 170
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Thailand – 70
Kenya – 70
Italy – 50
Note:
Value in US $ million
Florigene, an Australian-based industry is one of the pioneers in cut flower business. The company was established in 1986 and adopted gene technology to add value to cut flowers particularly to two of the most popular flowers rose and carnations. The company has acquired or pending more than 50 patents to its credit for introducing gene into these crops.
Extending Vase Life of Cut Flowers:
Post-harvesting of flower generally show senescence process after particular period of time. Senescence in physiological process which results in the fading of the cut flowers. Sometime lifespan of many flowers is limited by premature petal senescence.
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Several types of flower show increase in the production of ethylene hormone which in turn triggers senescence process leading to drying of flowers. Increase of vase life of flower is a major goal in cut flower industry. Antisense RNA has played a major role in cut flower industries particularly adding the value of vase life.
Control of Ethylene Production:
The vase life of flower can be increased by interfering with the biosynthesis of ethylene. The enzyme ACC synthase and ACC oxidase are key enzymes are responsible for senescence. Several example of transgenic ornamental like carnation expressing antisense ACC oxidase and producing flowers with feeble amount of ethylene and a marked delay in petal senescence.
Transgenic experiment proved that extended vase-life was confirmed upto 200%. Carnation was the only engineered ornamental released for commercialization. Approval has been granted to Australia for carnation transferred with sense ACC synthase gene.
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Ethylene Insensitive Petunias:
There have been reports that transgenic plants producing very less amount of ethylene, but continue to ripen in fruits and senescence as in case of cut flowers. The excess reduction can be correlated to the presence of ethylene receptors. Ethylene binds to the receptors ETR1 and ETR2 and initiates progression of ripening. A mutant gene for ethylene receptor has been identified in Arabidopsis thaliana, which is insensitive to ethylene binding.
Mutant gene of ETR1 and ETR2 from Arabidopsis was transferred to petunia. Transgenic plants with antisense ACS and ACO transgene sensitive to exogenous ethylene. However, transgenic plants are with mutants of expressing genes ETR1 and ETR2 are completely insensitive to exogenous ethylene and producing long-lasting flower.
In addition to above, several other strategies have been enforced to increase vase life of flowers includes overexpression of SAM hydrolases and ACC deaminase gene to block ethylene production. Expression of isopentanyl transferase gene and the control of strong promoter results in higher level of cytokinin, which normally prevents senescence process.
