Application of Conventional and Mutation Approaches in Genetic Improvement of Tuberose (Polianthes tuberosa L.): A Review on Recent Development and Future Perspectives

In recent days, improved conventional techniques, including division of the bulbs, removal of leaf and flower spikes, standard size of the bulb, and mechanical removal of sprouts, have been used to obtain improved quality planting materials in tuberose. Mutation breeding is also another technique that is used for improvement in tuberose. In mutation breeding, novelty can be created in an already well-established cultivar. Any change in the genes and their expression can be easily measured in the first generation of mutants by selecting desirable characters like flower color, shape, size, fragrance, etc. In the present review, the works carried out on tuberose by various workers worldwide from the last 40 years have witnessed conventional and mutation approaches made in the genetic improvement of tuberose. This review also highlights the role of selection for the identification of desirable traits, self-compatibility, and hybridization approaches made in tuberose species worldwide by several research institutions. Factors that affected mutation efficiency have also been presented and discussed from available data. Overall, the present reviews provide a consolidated account for the application of traditional and mutations approaches and suggest how their implications can be useful for genetic improvement of tuberose.

• Inter-specific hybridization plays an important role in the genetic improvement of tuberose. Inter- specific hybridization with species like P. howardii and P. geminiflora would be very effective to achieve colored cultivars in tuberose.

• Mutation techniques and their implications in breeding programs are efficient and cost-effective tools that can be exploited for genetic improvement in quantitative and qualitative traits like a different color of foliage, number of flowers with various ranges of color, sizes of flowers, and longer spikes.

• There are different types of radiation among the physical mutagens like gamma rays, x-rays, and chemical mutagens like Ethyl Methane Sulphonate (EMS) and Methyl Methane Sulphonate (MMS) are very effective to induce variability in tuberose. Lower concentrations of physical and chemical mutagens can induce variations in foliage and flowering traits of tuberose.