Xue Xueyi, Beuchat Gabriel, Wang Jiang, Yu Ya-Chi, Moose Stephen, Chen Jin, Chen Li-Qing
Department of Energy (DOE) Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Institute for Sustainability, Energy, and Environment, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Front Plant Sci. 2023 Sep 11;14:1233813. doi: 10.3389/fpls.2023.1233813. eCollection 2023.
Sweet sorghum has emerged as a promising source of bioenergy mainly due to its high biomass and high soluble sugar yield in stems. Studies have shown that loss-of-function locus alleles have been selected during sweet sorghum domestication, and decapitation can further boost sugar accumulation in sweet sorghum, indicating that the potential for improving sugar yields is yet to be fully realized. To maximize sugar accumulation, it is essential to gain a better understanding of the mechanism underlying the massive accumulation of soluble sugars in sweet sorghum stems in addition to the locus. We performed a transcriptomic analysis upon decapitation of near-isogenic lines for mutant (, juicy stems, and green leaf midrib) and functional (, dry stems and white leaf midrib) alleles at the locus. Our analysis revealed that decapitation suppressed photosynthesis in leaves, but accelerated starch metabolic processes in stems. negatively correlates with sugar levels supported by genotypes ( vs. ), treatments (control vs. decapitation), and developmental stages post anthesis (3d vs.10d). locus gene and other programmed cell death-related genes were downregulated by decapitation, while sugar transporter-encoding gene was induced. Both and were detected in phloem companion cells by RNA assay. Loss of the homolog, in led to a sugar accumulation increase. This study provides new insights into sugar accumulation enhancement in bioenergy crops, which can be potentially achieved by reducing reproductive sink strength and enhancing phloem unloading.
甜高粱已成为一种有前景的生物能源来源，主要是因为其生物量高且茎中可溶性糖产量高。研究表明，在甜高粱驯化过程中选择了功能缺失位点等位基因，去头处理可进一步提高甜高粱中的糖分积累，这表明提高糖分产量的潜力尚未完全实现。为了使糖分积累最大化，除了该位点外，深入了解甜高粱茎中可溶性糖大量积累的潜在机制至关重要。我们对该位点突变型（多汁茎和绿叶中脉）和功能型（干茎和白叶中脉）等位基因的近等基因系进行去头处理后进行了转录组分析。我们的分析表明，去头处理抑制了叶片中的光合作用，但加速了茎中的淀粉代谢过程。该位点与基因型（突变型与功能型）、处理（对照与去头）以及花后发育阶段（3天与10天）所支持的糖水平呈负相关。该位点基因及其他程序性细胞死亡相关基因在去头处理后下调，而糖转运蛋白编码基因被诱导。通过RNA原位杂交检测发现两者均存在于韧皮部伴细胞中。该同源物在突变体中的缺失导致糖分积累增加。本研究为生物能源作物中糖分积累增强提供了新见解，这可能通过降低生殖库强度和增强韧皮部卸载来实现。
