Sugar Metabolism during Growth and Development in Sugarcane Internodes

Abstract

Development of sugarcane (Saccharum spp. hybrids) genotypes with higher sucrose concentrations is desirable. Activities of sucrosemetabolizing enzymes during development of internodal storage tissue may determine the rate of total sugar accumulation and final sucrose concentration. Internodes of seven commercial cultivars were tagged prior to elongation and sampled at intervals from July until December during two growing seasons. Internode elongation was completed by about 380°C d (base temperature 18°C). Dry matter accumulated until about 800°C d. Water content decreased from about 920 to about 720 g kg−1 fresh weight (FW). Soluble acid invertase and sucrose synthase (sucrose cleavage direction) had peaks of activity during elongation, then declined to lower levels. Neutral invertase and sucrose‐phosphate synthase activities increased during development. Sugar accumulated, and the sucrose to total sugar ratio approached 1.0 as internodes developed, although the combined sucrose cleavage activity of the invertases and sucrose synthase in most internodes was greater than the synthetic activity of sucrose‐phosphate synthase. Sugar accumulation rate was not consistently correlated with activity of any enzyme assayed. Sucrose content during internode development was correlated with sucrose‐phosphate synthase activity and the difference between sucrose‐phosphate synthase and acid invertase activities. Sucrose content of mature internodes was not correlated with any enzyme activity. The data do not support the hypothesis that sucrose synthase activity is related to the rate of sugar accumulation, but do support the hypothesis that sucrose‐phosphate synthase and acid invertase play key roles in determining sucrose concentration during maturation in sugarcane internodes.

Plant regulators and invertase activity in sugarcane at the beginning of the harvest season

“…With regard to the acid isozyme, high acid isozyme levels, as evidenced by some research results, may be associated with the function of this enzyme in the regulation of growth in immature tissues; a positive correlation can be established between acid invertase activity and elongation rate LINGLE, 1999). JOSHI et al (2013) observed reduced SAI activity 12 months after planting (MAP) in all portions of the cane but after 13 MAP was noticed a slight increase at top and bottom internodes.…”

“…According to GAYLER &GLASZIOU (1972) andLINGLE (1999), SAI activity is responsiblefor the variations in sugar contents during growth, since it seems to be closely and inversely related to sucrose and total sugars contents. There have been reports of correlation between low acid isozyme levels under low temperature conditions (winter) and an increase in sucrose content during the sugarcane ripening process (ZHU et al, 1997;TERAUCHI et al, 2000); however, ROSE & BOTHA (2000) demonstrated a significant correlation between sucrose content and NI level.…”

“…This enzyme, together with low acid invertase levels in the cell wall, governs active sucrose accumulation in the vacuole. Later, in more mature tissues, which have sucrose content around 15 to 20%, sucrose storage will occur in the intercellular spaces (LINGLE, 1999). According to CHANDRA et al (2012), in storage sinks, invertase activity isimportant for creating a sucrose concentration gradientfrom the phloem to the sink tissue, and then maintainingthe storage sink for promoting phloemunloading.…”

Atividade das enzimas invertases e acúmulo de sacarose em cana-de-açúcar sob efeito do nitrato de potássio, etefon e etil-trinexapac

“…As flutuações nos teores de açúcar durante o crescimento vegetal, conforme Lingle (1999), é consequência do nível da enzima SAI, tendo em vista que a SAI apresenta relação estreita e inversa com o conteúdo de sacarose e açúcares totais. Outras pesquisas enfatizaram redução na atividade desta enzima sob condições de baixas temperaturas e com a ocorrência do processo de maturação da cana-de-açúcar, correlacionando-a com o aumento na concentração de sacarose (ZHU et al, 1997;ECHEVERRIA, 1998;TERAUCHI et al, 2000).…”

“…Diversos resultados de pesquisas têm enfatizado a correlação inversa entre o nível de atividade da SAI e o conteúdo de sacarose em colmos de cana-de-açúcar ( HAWKER, 1985;ZHU et al, 1997;LINGLE, 1999;TERAUCHI et al, 2000;GUIMARÃES et al, 2005). Por outro lado, há relatos na literatura enfatizando que elevados níveis da NI em relação a SAI pode refletir na capacidade efetiva de armazenamento de sacarose (HATCH; GLASZIOU, 1963;SOVIA, 1974;ROSE;BOTHA, 2000).…”