Liu Bailin, Zhang Guodong, Murphy Agnes, De Koeyer David, Tai Helen, Bizimungu Benoit, Si Huaijun, Li Xiu-Qing
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University , Yangling, Shaanxi 712100, People's Republic of China.
Potato Research Centre, Agriculture and Agri-Food Canada , 850 Lincoln Road, Post Office Box 20280, Fredericton, New Brunswick E3B 4Z7, Canada.
J Agric Food Chem. 2016 Feb 10;64(5):1176-84. doi: 10.1021/acs.jafc.5b05238. Epub 2016 Jan 29.
Potatoes usually have the tuber bud end dominance in growth during tuber bulking and in tuber sprouting, likely using carbohydrates from the tuber stem end. We hypothesized that the tuber bud end and tuber stem end coordination in carbohydrate metabolism gene expression is different between the bulking dominance and sprouting dominance of the tuber bud end. After comparing the growing tubers at harvest from a green vine and the stage that sprouts just started to emerge after storage of tubers at room temperature, we found the following: (1) Dry matter content was higher in the tuber stem end than the tuber bud end at both stages. (2) The starch granule size was larger in the tuber bud end than in the tuber stem end. (3) The tuber bud end had higher gene expression for starch synthesis but a lower gene expression of sucrose transporters than the tuber stem end during tuber growing. (4) The tuber stem end at the sprouting stage showed more active gene expression in both starch degradation and resynthesis, suggesting more active export of carbohydrates, than the tuber bud end. The results indicate that the starch accumulation mechanism in the tuber bud end was different between field growing and post-harvest sprouting tubers and that tubers already increased dry matter and average starch granule sizes in the tuber bud end prior to the rapid growth of sprouts.
在块茎膨大期和块茎发芽期，马铃薯通常在生长过程中表现出块茎芽端优势，可能利用来自块茎茎端的碳水化合物。我们推测，在块茎芽端的膨大优势和发芽优势之间，碳水化合物代谢基因表达中块茎芽端和块茎茎端的协调性是不同的。在比较了从绿蔓上收获的正在生长的块茎以及在室温下储存块茎后刚开始发芽的阶段后，我们发现了以下情况：(1) 在两个阶段，块茎茎端的干物质含量均高于块茎芽端。(2) 块茎芽端的淀粉颗粒尺寸大于块茎茎端。(3) 在块茎生长期间，块茎芽端淀粉合成的基因表达较高，但蔗糖转运蛋白的基因表达低于块茎茎端。(4) 在发芽阶段，块茎茎端在淀粉降解和再合成方面均表现出更活跃的基因表达，表明碳水化合物的输出比块茎芽端更活跃。结果表明，田间生长的块茎和收获后发芽的块茎在块茎芽端的淀粉积累机制不同，并且在芽快速生长之前，块茎芽端的干物质和平均淀粉颗粒尺寸已经增加。
