Identification of molecular markers for developing breeding strategies in rose

Abstract

Rose, one of the most important flowering ornamentals is a favourite for landscaping and an important commercial cut flower. Breeders are always looking for new and novel varieties to meet the ever increasing demand of consumers. However, many years are required to develop a new variety through conventional methods.

Many desirable roses are female sterile and hence pose a real limitation to breeding. Developing a molecular marker that can readily identify a female parent can go a long way to avoid unproductive hybrids. Premature abortion of developing embryos resulting in few or no viable seeds is another major set back.

The present investigation entitled ‘Identification of molecular markers for developing breeding strategies in rose’ was held out at this context at the Centre of Plant Biotechnology and Molecular Biology (CPBMB) with the aim of determining a molecular marker and attempting embryo rescue of rose.

Fifty rose varieties were selected based on morphological characters viz., seed setting ability. Variations in foliar characters of plants were recorded. Genomic DNA extraction from tender leaves of rose plants using Roger and Bendich’s method (1994) with slight modification was found to be the best.

Out of fifty-one primers screened four primers belonging to OPAA 2 , C 4, C 15 and C19 were identified as the best. Molecular characterization by RAPD assay generated a total of 331 amplification products. Some bands were specific or prominent to the group. The clustering of sterile and fertile varieties mostly into two separate clusters indicated their similarity at the genetic level. Further studies have to be conducted by increasing the number of primers used, for identification of fertility status of more varieties.

In view of the problems faced by breeders regarding unproductive hybrids, an attempt was made for embryo rescue. Surface sterilization of hips with 0.1 per cent mercuric chloride was standardized. The pollen fertility was assessed by acetocarmine staining and mean fertility was observed to be 74.6 per cent. The poor response of germination observed for achenes was due to both physical and chemical restriction on the embryo. Effect of media type and combination of growth regulators were assessed. A high germination rate was observed in cultures incubated for two weeks in dark and subsequently transferred to light. Inoculation media with BA and IAA and subculturing media with BA and NAA combined with low salt concentration (half MS) was found to give maximum response. Further trials can lead to the identification of a definite protocol for regeneration.