生物谷報道：美國德克薩斯農(nóng)業(yè)實驗站的植物生理學(xué)家Lee Tarpley博士與作物生理學(xué)教授Don Vietor博士經(jīng)過研究發(fā)現(xiàn)：雖然甜高粱和蔗糖是近親,，但是,，這兩個物種有著不同的糖類運輸方式和儲存方式。
研究人員利用與靜脈血管相似的系統(tǒng)將蔗糖追蹤器植入生長中的植物上,，通過這個追蹤器,，可以監(jiān)測到蔗糖的運動和分布。研究發(fā)現(xiàn)：由于植物的生理作用,，甜高粱可以更有效地利用體內(nèi)儲存的糖類供給其它部位生長需要,；而甘蔗則利用這種機制在體內(nèi)累積了大量的蔗糖。
Tarpley表示：目前關(guān)于甘蔗的研究較多,，其研究結(jié)果此前一度被認(rèn)為可以適用于高粱,。而了解這兩種作物之間的生理差異對于開發(fā)適合生物燃料工業(yè)的新品種是至關(guān)重要的。他表示：雖然高粱是一年生的植物,，但是適合輪種,，而在許多地區(qū)甘蔗是多年生的植物。為了最大程度地發(fā)掘甜高粱作為生物燃料作物的潛力,，耕作者需要詳細(xì)了解它的生理特征,，而不能簡單地參考甘蔗,。
該項研究結(jié)果發(fā)表在《英國醫(yī)學(xué)委員會植物生物學(xué)》雜志上。（教育部科技發(fā)展中心）
原文鏈接：http://www.sciencedaily.com/releases/2007/09/070912154613.htm
原始出處:
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.
