ABSTRACT. Sugarcane breeding under climatic conditions of Pakistan is very difficult due to unavailability of viable fuzz (seed). Somaclonal variation can provide an alternative for improvement of existing genotypes. Six hundred and twenty-seven somaclones were developed from sugarcane genotype S97US297, and protocols for callogenesis and organogenesis were developed using Murashige and Skoog medium. Two types of explants, leaf and pith, and two auxins, 2,4-dichlorophenoxy acetic acid and indole-3-acetic acid, were tested to optimize callogenesis for root establishment. Leaves as explants with 3.0 mg/L 2,4-dichlorophenoxy acetic acid gave the best results, both for callus induction and proliferation. Half-strength Murashige and Skoog medium with 1.5 mg/L indole-3-butyric acid proved to be the best for rooting. Red rot-resistant somaclones of the R 2 generation along with the parent were assessed for genetic variability at the molecular level using RAPD and SSR markers. Polymorphism based on RAPD and SSR was 32 and 67%, respectively. Polymorphic information content ranged from 0.06-0.45 for RAPD and 0.06-0.47 for SSR. We conclude that somaclonal variation of sugarcane varieties is sufficient to allow selection.

Worldwide, sugarcane (Saccharum officinarum L) is the major source of commercial sugar along with many other value added products. In Pakistan, during the year 2008 to 2009, there was a production of 50.05 million tonnes. Sugarcane genotype BF-162 was released for general use in the Punjab province during 1990, and it became susceptible to red rot. As environmental conditions are not conducive for flowering, so the red rot rectification was tried through somaclonal variation. Protocol for callogenesis and organogenesis was standardized. Leaf when used as explant source and 2,4dichlorophenoxyacetic acid (2,4-D) as auxin at 3mg/l performed better in callogenesis. It was observed that lower doses of Kinetin regenerated more numbers of shoots, while indole-3-butyric acid (IBA) developed more numbers of roots. Red rot resistance somaclones were isolated and assessed for the presence of variability through random amplified polymorphic DNA (RAPD) and simple sequence repeats (SSR) markers. Polymorphism captured by RAPD was 33.73% and by SSR was 64%. Polymorphic information content (PIC) value ranged between 0.02 and 0.45 for RAPD and 0.12 and 0.49 for SSR. Cluster and sub cluster formation further verified the presence of variability in the red rot resistant somaclones with respect to the parent.

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