Sweet versus grain sorghum: Differential sugar transport and accumulation are linked with vascular bundle architecture

•Sugar accumulation in sweet sorghum was significantly increased after flowering.•Sugar accumulation correlates with phloem to xylem cross areas in internodes.•Accumulation SbSUT transcripts cannot account for differential accumulation of sugar in stem between sweet and grain sorghum.•The response of SbSUT transcripts to salt stress differs between sweet and grain sorghum.•Sweet sorghum exhibited an enhanced response to salt stress compared with grain sorghum.