Induction and evaluation of colchitetraploids of two species of Tinospora Miers, 1851.

Rakesh Kr Thakur,Satyawada Rama Rao,Vijay Rani Rajpal,Soom Nath Raina,Apekshita Singh,Pankaj Kaushal,Lata Joshi

doi:10.3897/compcytogen.v14i2.33394

Abstract

Autotetraploidy, both natural and/or induced, has potential for genetic improvement of various crop species including that of medicinal importance. Tinospora cordifolia (Willdenow, 1806) Miers, 1851 ex Hooker et Thomson, 1855 and T. sinensis (Loureiro, 1790) Merrill, 1934 are two diploid species, which are dioecious, deciduous and climbing shrubs with high medicinal importance. Among the three methods used for induction of polyploidy by colchicine treatment, it was cotton swab method which successfully induced the polyploidy in both species. The morphological and cytogenetical features of the synthetic tetraploids were compared with their diploid counterparts. The tetraploids were morphologically distinct from diploid plants. They exhibited larger organs, such as stem, leaves, inflorescence, fruits, flowers and seeds. The tetraploids were characterized by the presence of low quadrivalent frequency and high bivalent average. Unequal distribution of chromosomes at anaphase I was found in 60% cells. The present study provides important information on the superiority of autotetraploids as compared to diploid counterparts in both species.

Highlights

Polyploidy, the presence of more than two sets of chromosomes, has played a pivotal role in the diversity, evolution, genetic improvement and speciation of both wild and cultivated plants (Sattler et al 2016)
Thirteen hundred seeds/seedlings/vegetative buds each of T. cordifolia and T. sinensis were treated with three different concentrations (0.1, 0.15 and 0.2%) of aqueous colchicine for 6 or 12 h each for 2, 3, 4 or 5 days (Table 1)
Out of 700 seedlings each in T. cordifolia and T. sinensis treated by cotton swab method, 349 and 284 seedlings survived (Table 1) and out of these, based on flow cytometry and male meiosis, 14(~4%) and 8(~2.8%) were found to be colchitetraploid plants, respectively

Summary

Introduction

Polyploidy, the presence of more than two sets of chromosomes, has played a pivotal role in the diversity, evolution, genetic improvement and speciation of both wild and cultivated plants (Sattler et al 2016). Due to aberrant meiosis and resultant low seed set, induced autopolyploidy has been considered relatively more rewarding in such plants where vegetative or floral parts have commercial value and the plant propagates by vegetative means (Lavania 2005). Induced polyploidy may lead to enhanced production and qualitative changes in secondary metabolites due to perceived increase in number of gene copies and probably the enzyme content of polyploids (Dhawan and Lavania 1996, Sattler et al 2016)

Methods

Results

Discussion

Conclusion