A Rare Occurrence of 2n Gametes Functioning in Interspecific Crosses Involving Commercial Cultivar of Sugarcane (Co 89029) and Saccharum spontaneum L.

Functioning of n and 2n gametes in sugarcane is a cytogenetic peculiarity with specific crosses involving different species and genera of the Saccharum complex. The 2n + n transmission is predominant in crosses of S. officinarum and S. spontaneum, and this had earlier led to the success of the first evolved variety ‘Co 205’ in 1918. Exceptions of n + n gametes have also been reported later. However, transmission of 2n gametes in the crosses involving commercial varieties and S. spontaneum is a rare occurrence. Transmission of n + n is the major limitation in prebreeding of sugarcane for introgression of S. spontaneum (2n = 40–128) genome into commercial varieties as donor for incorporating pest and disease resistance, wider adaptability, high tillering, etc. The F₁ progenies have to be backcrossed for several generations in varietal developmental programme^1,2. Hence selection of hybrids with female restitution in wide crosses is highly advantageous in nobilization programme.