Common metabolic networks contribute to carbon sink strength of sorghum internodes: implications for bioenergy improvement

Abstract

BackgroundSorghum bicolor (L.) is an important bioenergy source. The stems of sweet sorghum function as carbon sinks and accumulate large amounts of sugars and lignocellulosic biomass and considerable amounts of starch, therefore providing a model of carbon allocation and accumulation for other bioenergy crops. While omics data sets for sugar accumulation have been reported in different genotypes, the common features of primary metabolism in sweet genotypes remain unclear. To obtain a cohesive and comparative picture of carbohydrate metabolism between sorghum genotypes, we compared the phenotypes and transcriptome dynamics of sugar-accumulating internodes among three different sweet genotypes (Della, Rio, and SIL-05) and two non-sweet genotypes (BTx406 and R9188).ResultsField experiments showed that Della and Rio had similar dynamics and internode patterns of sugar concentration, albeit distinct other phenotypes. Interestingly, cellulose synthases for primary cell wall and key genes in starch synthesis and degradation were coordinately upregulated in sweet genotypes. Sweet sorghums maintained active monolignol biosynthesis compared to the non-sweet genotypes. Comparative RNA-seq results support the role of candidate Tonoplast Sugar Transporter gene (TST), but not the Sugars Will Eventually be Exported Transporter genes (SWEETs) in the different sugar accumulations between sweet and non-sweet genotypes.ConclusionsComparisons of the expression dynamics of carbon metabolic genes across the RNA-seq data sets identify several candidate genes with contrasting expression patterns between sweet and non-sweet sorghum lines, including genes required for cellulose and monolignol synthesis (CesA, PTAL, and CCR), starch metabolism (AGPase, SS, SBE, and G6P-translocator SbGPT2), and sucrose metabolism and transport (TPP and TST2). The common transcriptome features of primary metabolism identified here suggest the metabolic networks contributing to carbon sink strength in sorghum internodes, prioritize the candidate genes for manipulating carbon allocation with bioenergy purposes, and provide a comparative and cohesive picture of the complexity of carbon sink strength in sorghum stem.

Mining Sorghum Biodiversity—Potential of Dual-Purpose Hybrids for Bio-Economy

“…This result is consistent with earlier observations showing that it was the central internodes in sorghum stems that displayed the highest • Brix [27,51,59]. The sweet sorghum cultivars Della and Rio showed similarities in the internode sugar concentration dynamics, whereas in both genotypes, the total sugar concentration was remarkably increased after anthesis and the upper and lower internodes had lower sugar concentrations compared to the middle internodes [60].…”

Editorial: Advances in crop biomass production based on multi-omics approach

“…Sugarcane is one of the key biomass and bioenergy crops, providing about 80% of global sugar production and 40% of ethanol production (Zhang et al, 2018). Efforts have been made to investigate the molecular mechanisms of sugar accumulation in sugarcane and in the comparable species sweet sorghum (Li et al, 2018;Li et al, 2019a;Li et al, 2019b), from sugar transportation and physiology to transcriptome and quantitative trait loci mapping (Babu et al, 2009;Moore, 2005;Aitken et al, 2006;Casu et al, 2007;Zhang et al, 2021). Yuan et al performed transcriptomic and metabolomic studies on two sugarcane varieties and revealed candidate genes for sucrose metabolism, stem texture, and rind color.…”

Correction to: Common metabolic networks contribute to carbon sink strength of sorghum internodes: implications for bioenergy improvement

“…The original version of the article [1] unfortunately contained a mistake in author’s first name. The name of the author has been corrected from Wenqing Wang to Wenqin Wang in this correction article.…”

“…The name of the author has been corrected from Wenqing Wang to Wenqin Wang in this correction article. The original article [1] has been corrected.…”