Zhu Lin, Zhang Jisen, Chen Youqiang, Pan Hongyu, Ming Ray
College of Plant Science, Jilin University, Changchun, Jilin, 130062, China.
Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Funct Plant Biol. 2013 May;40(4):369-378. doi: 10.1071/FP12182.
Sugarcane contributes ~80% of sugar production in the world and is an established biofuel crop. In working towards understanding the molecular basis of high sucrose accumulation, we have annotated and analysed the ATP-dependent phosphofructokinase (PFK) gene family that catalyses the phosphorylation of D-fructose 6-phosphate to D-fructose 1,6-bisphosphate. PFKs play an essential role in sucrose metabolism in plants and their expression patterns are unknown in sugarcane. In this study, based on the sorghum genome and sugarcane EST database, 10 PFK gene members were annotated and further verified by PCR using sugarcane genomic DNA. An unrooted phylogenetic tree was constructed with the deduced protein sequences of PFKs that were from the assembly of cDNA library of sugarcane and other plants. The results showed that gene duplication events and the retention rate after genome wide or segmental duplications occurred in higher frequency in monocots than in dicots and the genes in subgroup II of group III were likely originated from recent duplication events. Quantitative RT-PCR was performed to investigate the gene expression of 10 PFK genes in five tissues of three Saccharum species, including two developmental stages in leaves and three in culms. Of the PFK family members in sugarcane, ScPFK6, 7 and 8 appeared to be the primary isoforms based on the highly abundant expression of these three genes. ScPFK7 showed high expression level in the leaves, suggesting a potential role in sucrose metabolism. ScPFK8 had lower expression level in Saccharum officinarum L. than in the other two species, suggesting negative regulation of sucrose metabolism, which might have contributed to the high sugar content of S. officinarum. The genes in monocot specific subgroup II of group III, PFK7, 8 and 9, showed variation among the three Saccharum species, suggesting potential functional redundancy. Our results provide detailed annotation and analysis of the PFK gene family in sugarcane. Further elucidation of the role of ScPFK8 in the domestication process of sugarcane would be useful.
甘蔗贡献了全球约80%的食糖产量，是一种成熟的生物燃料作物。为了深入了解高蔗糖积累的分子基础，我们对ATP依赖性磷酸果糖激酶（PFK）基因家族进行了注释和分析，该基因家族催化D-果糖6-磷酸磷酸化为D-果糖1,6-二磷酸。PFK在植物蔗糖代谢中起着至关重要的作用，其在甘蔗中的表达模式尚不清楚。在本研究中，基于高粱基因组和甘蔗EST数据库，注释了10个PFK基因成员，并使用甘蔗基因组DNA通过PCR进一步验证。利用甘蔗和其他植物cDNA文库组装得到的PFK推导蛋白序列构建了无根系统发育树。结果表明，单子叶植物中全基因组或片段重复后的基因重复事件和保留率高于双子叶植物，且第三组第二亚组中的基因可能起源于近期的重复事件。进行了定量RT-PCR以研究10个PFK基因在三种甘蔗品种的五个组织中的基因表达，包括叶片的两个发育阶段和茎秆的三个发育阶段。在甘蔗的PFK家族成员中，基于这三个基因的高丰度表达，ScPFK6、7和8似乎是主要的同工型。ScPFK7在叶片中表达水平较高，表明其在蔗糖代谢中可能发挥作用。ScPFK8在甘蔗中表达水平低于其他两个品种，表明其对蔗糖代谢有负调控作用，这可能是甘蔗高糖含量的原因之一。第三组单子叶植物特异性第二亚组中的基因PFK7、8和9在三种甘蔗品种中表现出差异，表明可能存在功能冗余。我们的结果提供了甘蔗中PFK基因家族的详细注释和分析。进一步阐明ScPFK8在甘蔗驯化过程中的作用将很有帮助。
