寡肽是一类由几个氨酸酸缩合成的短肽，寡肽不仅可以作为生物体物质能量代谢所必需的碳源或氮源，它本身也可以作为信号分子发挥多种生物学功能，而寡肽转运体的主要功就是高效地将寡肽从胞外转运到胞内。寡肽转运体的研究相比集中在细菌与动物方面，植物寡肽转运体的相关研究相对较少。
OPT家族基因研究
中国科学院昆明植物研究所、青藏高原研究所昆明部杨永平研究组与胡向阳研究组，联合美国东卡罗来纳大学的黄锦岭教授与江苏大学的曹军博士，对于杨树与葡萄中的寡肽转运体基因家族展开基因组学方面的研究。进化树分析表明，杨树与葡萄中的OPT家族基因明显呈现出两个分枝，进一步可以细化成十个分枝；OPT家族基因在染色体中呈现非随机的串联重复方式分布，暗示基因重复在杨树与葡萄中适应性进化中的重要作用；基因芯片结果表明，杨树与葡萄中的OPT家族基因参与了生长发育及多种逆境响应过程；正选择分析表明，整个OPT基因家族受到强烈的负选择，但是针对某些特定的位点，进化压力依旧表现出正选择，并且这些位点都是膜外或膜内，表明这种选择与环境适应之间的相关性。
这些结果有助于人们进一步理解植物OPT基因家族的进化与功能适应。（来源：中国科学院）
相关英文论文摘要：
Analyses of the oligopeptide transporter gene family in poplar and grape
Background
Oligopeptide transporters (OPTs) are a group of membrane-localized proteins that have a broad range of substrate transport capabilities and that are thought to contribute to many biological processes. The OPT proteins belong to a small gene family in plants, which includes about 25 members in Arabidopsis and rice. However, no comprehensive study incorporating phylogeny, chromosomal location, gene structure, expression profiling, functional divergence and selective pressure analysis has been reported thus far for Populus and Vitis.
Results
In the present study, a comprehensive analysis of the OPT gene family in Populus (P. trichocarpa) and Vitis (V. vinifera) was performed. A total of 20 and 18 full-length OPT genes have been identified in Populus and Vitis, respectively. Phylogenetic analyses indicate that these OPT genes consist of two classes that can be further subdivided into 11 groups. Gene structures are considerably conserved among the groups. The distribution of OPT genes was found to be non-random across chromosomes. A high proportion of the genes are preferentially clustered, indicating that tandem duplications may have contributed significantly to the expansion of the OPT gene family. Expression patterns based on our analyses of microarray data suggest that many OPT genes may be important in stress response and functional development of plants. Further analyses of functional divergence and adaptive evolution show that, while purifying selection may have been the main force driving the evolution of the OPTs, some of critical sites responsible for the functional divergence may have been under positive selection.
Conclusions
Overall, the data obtained from our investigation contribute to a better understanding of the complexity of the Populus and Vitis OPT gene family and of the function and evolution of the OPT gene family in higher plants.
