生物谷报道：美国德克萨斯农业实验站的植物生理学家Lee Tarpley博士与作物生理学教授Don Vietor博士经过研究发现：虽然甜高粱和蔗糖是近亲，但是，这两个物种有着不同的糖类运输方式和储存方式。
研究人员利用与静脉血管相似的系统将蔗糖追踪器植入生长中的植物上，通过这个追踪器，可以监测到蔗糖的运动和分布。研究发现：由于植物的生理作用，甜高粱可以更有效地利用体内储存的糖类供给其它部位生长需要；而甘蔗则利用这种机制在体内累积了大量的蔗糖。
Tarpley表示：目前关于甘蔗的研究较多，其研究结果此前一度被认为可以适用于高粱。而了解这两种作物之间的生理差异对于开发适合生物燃料工业的新品种是至关重要的。他表示：虽然高粱是一年生的植物，但是适合轮种，而在许多地区甘蔗是多年生的植物。为了最大程度地发掘甜高粱作为生物燃料作物的潜力，耕作者需要详细了解它的生理特征，而不能简单地参考甘蔗。
该项研究结果发表在《英国医学委员会植物生物学》杂志上。（教育部科技发展中心）
原文链接：http://www.sciencedaily.com/releases/2007/09/070912154613.htm
原始出处:
BMC Plant Biology 2007, 7:33doi:10.1186/1471-2229-7-33
Published: 20 June 2007
Compartmentation of sucrose during radial transfer in mature sorghum culm
Lee Tarpley1 and Donald M Vietor2
1Texas A&M Agricultural Research and Extension Center, 1509 Aggie Dr., Beaumont, TX 77713, USA
2Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, USA
author email corresponding author email
Background
The sucrose that accumulates in the culm of sorghum (Sorghum bicolor (L.) Moench) and other large tropical andropogonoid grasses can be of commercial value, and can buffer assimilate supply during development. Previous study conducted with intact plants showed that sucrose can be radially transferred to the intracellular compartment of mature ripening sorghum internode without being hydrolysed. In this study, culm-infused radiolabelled sucrose was traced between cellular compartments and among related metabolites to determine if the compartmental path of sucrose during radial transfer in culm tissue was symplasmic or included an apoplasmic step. This transfer path was evaluated for elongating and ripening culm tissue of intact plants of two semidwarf grain sorghums. The metabolic path in elongating internode tissue was also evaluated.
Results
On the day after culm infusion of the tracer sucrose, the specific radioactivity of sucrose recovered from the intracellular compartment of growing axillary-branch tissue was greater (nearly twice) than that in the free space, indicating that sucrose was preferentially transferred through symplasmic routes. In contrast, the sucrose specific radioactivity in the intracellular compartment of the mature (ripening) culm tissue was probably less (about 3/4's) than that in free space indicating that sucrose was preferentially transferred through routes that included an apoplasmic step. In growing internodes of the axillary branch of sorghum, the tritium label initially provided in the fructose moiety of sucrose molecules was largely (81%) recovered in the fructose moiety, indicating that a large portion of sucrose molecules is not hydrolysed and resynthesized during radial transfer.
Conclusion
During radial transfer of sucrose in ripening internodes of intact sorghum plants, much of the sucrose is transferred intact (without hydrolysis and resynthesis) and primarily through a path that includes an apoplasmic step. In contrast, much of the sucrose is transferred through a symplasmic path in growing internode (axillary branch) tissue. These results contrast with the probable symplasmic path in mature culm of the closely related species, sugarcane. Phylogenetic variability exists in the compartmental path of radial transfer of sucrose in culms of the andropogonoid grasses.
