Sucrose Metabolism in the Primary Culm of Sweet Sorghum During Development¹

Abstract

Sweet sorghum (Sorghum bicolor (L.) Moench] accumulates large amounts of sugar in culm parenchyma after anthesis, but the biochemical basis of this accumulation is not understood. This study was to identify the enzymes responsible for the pattern of sucrose accumulation in sweet sorghum. Sugars and four enzymes of sucrose metabolism were extracted from whole primary culms and individual internodes of primary culms of ‘Rio’ sweet sorghum at intervals during reproductive development. In whole culms, sucrose concentration increased seven‐fold between the boot and mid‐grain filling stages. This increase was accompanied by a decline in soluble acid invertase (pH optimum 5.0) and sucrose synthase activities. Soluble neutral invertase (pH optimum 7.0) activity was evident throughout, although its activity declined between soft dough and physiological maturity. Very low activity (<13 μmole·kg−1 FW·s−1) of sucrosephosphate synthase was also detected throughout development. At the flag leaf stage, the two uppermost internodes were still elongating. These internodes had the highest activities of acid and neutral invertase and sucrose synthase, and virtually no accumulation of sucrose. In succeeding growth stages, sucrose accumulated most rapidly in internodes below the top two. At anthesis, the top six internodes had similar activities, on a fresh weight basis, of all enzymes assayed. The onset of sucrose accumulation in sweet sorghum was associated with the onset of the reproductive phase of growth and the decrease in acid invertase activity, but sucrose concentration was not correlated with the activity of any enzyme. In this regard, sweet sorghum appears to be biochemically different from sugarcane (Saccharum spp.).

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

“…Sugar accumulation in the stem of grain and sweet sorghum cultivars Previous reports have indicated that in sorghum stems, sugars start to accumulate at flowering stage [16,25]. We compared the accumulation of sugars in the stem between six sweet sorghum lines (Dale, Della, M81-E, Rio, Top76-6, and Simon) and one line from grain sorghum (BTx623).…”

Changes in the sugar content of sweet sorghum stems under natural conditions during winter in saline soil of the Yellow River Delta

“…Previous studies have shown that the enzyme activities involving sucrose metabolism maintain a certain activity at low temperatures (Guy et al, 1992). of different varieties of sweet sorghum straw was not exactly the same (Lingle, 1987). The results of this study showed that the water content, total sugar content and main sugar content such as sucrose, glucose and fructose in the stalks of four sweet sorghum cultivars plants slightly decreased during the winter time from the early November 2016 to the March 2017, the lowest temperature was below 0°C, and the average temperature was near 0°C.…”

Comportamiento agronómico de líneas para la producción de semilla de sorgo

“…Esto explica la alta concentración de azúcares en las líneas A, B de sorgo y por tanto coincide con Lingle (1987) el cual reporta, que la madurez fisiológica del grano es la etapa óptima para la cosecha.…”