The Evolutionary Significance of Sugar Accumulation in Saccharum

Abstract

SummarySugar levels in the various species of the Saccharum complex suggest an evolutionary increase in sugar content. Under suitable ecological conditions, survival through sucker growth may be dependent on rapid mobilization of stored carbohydrate. Selection pressure for sucrose storage would then oocur if sucrose was more readily remobilized than other storage carbohydrates. It is suggested that this ecological situation occurred in New Guinea, and that natural and not human selection lead to the evolution of S. oJJicinarum.The relationships between total sugars, moisture content, and fibre content indicate that there is an apparent physiological limit to sugar accumulation in the genus Saccharum at about 27% of the fresh weight.

Screen of Genes Linked to High-Sugar Content in Stems by Comparative Genomics

“…In order to identify genes expressed in the stem with a potential role in sugar accumulation and reduced lignocellulose [4], we compared transcript profiles between grain (BTx623) and sweet sorghum (Rio). Such a genome-wide analysis became possible because of the recently designed GeneChip of sugarcane [6].…”

“…For these reasons, it is considered that GDP-mannose 3,5 epimerase could modulate the carbon flux into the vitamin C pathway as well as the demand for GDP-mannose into the cell wall biosynthesis [43]. Indeed, it is known that the stem of highsucrose-accumulating genotypes of sugarcane are high in moisture content and low in fiber, whereas the stem of lowsucrose-accumulating genotypes are low in moisture content, thin, and fibrous [4].…”

“…Interestingly, there is extensive natural intra-species variation for sugar content in sorghum with cultivars that do not accumulate sugars (referred to as grain sorghums) in contrast to those that accumulate large amounts of sugars in their stems [16]. Such intra-species variation can serve as a platform to identify genes linked to increased sugar content and reduced lignocellulose [4]. Moreover, if these genes are conserved by ancestry in related species, one could envision the introduction of such a trait by the import of specific regulatory regions.…”

The potential of the energy cane as the main biomass crop for the cellulosic industry

“…To accomplish that, nature will bring back its essential contribution: the ancestral species and genera that in millions of years led to the development of forms exploited by man should constitute the basis for the divergent selection of the new type of cane, the energetic plant. The potential existing in the Saccharum complex for this new divergent selection can be realized looking at the data from Bull and Glasziou [54] -among others in the literature -as presented in Table 2.…”

Preliminary Evaluation of Some Qualitative Traits of Sugarcane Germplasm of North-Western Nigeria

“…Traits such as biomass and sugar yield are met by different progeny testing stages before the choice of the best progeny clones is suggested for preliminary or advanced yield trials (Gill, 1999). Among environmental factors that have impact on sugarcane breeding are temperature (Bull and Glasziou, 1963), rainfall distribution (Olaoye, 2006), photoperiod, rising atmospheric concentrations of CO2 (Ehara and Takamura, 1994) and pollution levels. For example, intermittent occurences of night temperature below 18 o C, during the period of floral induction reduce flowering intensity and/or delay seedling emergence (Dunckelman and Breaux, 1969).…”