Investigation on in vitro bouquets and flower longevity of micropropagated Dianthus chinensis L.

Abstract

The commercial value of ornamental crops is governed by the quality and quantity of flowers it produces. In vitro flowers or test tube bouquets help the researchers to attain the molecular mechanism behind the flower development. In this work, we put forward, how such an ornamental species, Dianthus chinensis can be used as a model system for in vitro flowering studies, and investigate the feasibility of a promising substitute for potted plants. In ornamentals, floral longevity is considered as a leading factor for boosting the market demand. The cytokinin, 6-benzyladenine (BA) showed potential application on in vitro floral initiation and flower longevity. The treatment of ethephon or salicylic acid along with 2.5 μM BA in Murashige and Skoog (MS) medium gave flower initiation, but reduced longevity compared to 2.5 μM BA alone (42 days). However ethylene proved to be the cause of early flowering and senescence. The role of ethylene on in vitro flower senescence in 2.5 μM BA was elucidated using the ethylene biosynthesis gene (ACS1 and ACO1) expression was analyzed in petal samples of different flowering stages. The reduced ACS1 or ACO1 gene expression among the blooming stage may help to maintain the freshness of flowers in culture condition. To retain the reduced ethylene expression after blooming, in vitro raised microshoots with mature bud stage were transferred to MS medium containing different ethylene inhibiting compounds in combination with 2.5 μM BA, where addition of putrescine and silver nitrate showed maximum 54 days longevity in culture room condition and 32 days in normal room temperature. The extended longevity of in vitro produced flowers denotes its prospect in the development of in vitro bouquets, thus improved ornamental value of D. chinensis.