Somatic Embryogenesis in Sugarcane (Saccharum Species)

Abstract

Sugarcane is the name given to sacchariferous, cultivated species and descendants of interspecific hybrids in the genus Saccharum, fafnily Graminae, tribe Andropogonae. Saccharum species are highly polyploid with no known diploid form. A basic chromosome number has not yet been firmly established, but is estimated in the range of 5–10 (Stevenson 1965). Until the late 1800s, sugarcane varieties belonged mostly to S officinarum (2n = 8x = 80), the “noble” cane originating from New Guinea, and also to S sinense (2n = 106−120) and S. barberi (2n = 80−120). Interspecific crosses between S officinarum and S. spontaneum, followed by two or three backcrossings to the noble cane — a process called nobilization — yielded the first modern commercial varieties(Saccharum ssp.) in the early 1900s in Java and later in India (Daniels and Roach 1987). The original hybrids were, in turn, crossed with each other to produce new commercial varieties. The limited genetic basis of the original hybridizations, which according to Arceneaux (1967) involved no more than 20 noble clones and fewer than 10 S. spontaneum derivatives, led various countries to reinitiate nobilization work in the early 1960s in order to transfer specific, desirable characters, such as disease resistance, from wild germplasm to commercial hybrids (Berding and Roach 1987). Current breeding goals are to develop cultivars with increased sugar yield and resistance to diseases (smut, mosaic, rust, leaf scald) and insects.