Wang Bowen, Du Qingzhang, Yang Xiaohui, Zhang Deqiang
National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, P, R, China.
BMC Plant Biol. 2014 Mar 27;14:81. doi: 10.1186/1471-2229-14-81.
The gap between the real and potential photosynthetic rate under field conditions suggests that photosynthesis could potentially be improved. Nuclear genes provide possible targets for improving photosynthetic efficiency. Hence, genome-wide identification and characterization of the nuclear genes affecting photosynthetic traits in woody plants would provide key insights on genetic regulation of photosynthesis and identify candidate processes for improvement of photosynthesis.
Using microarray and bulked segregant analysis strategies, we identified differentially expressed nuclear genes for photosynthesis traits in a segregating population of poplar. We identified 515 differentially expressed genes in this population (FC ≥ 2 or FC ≤ 0.5, P < 0.05), 163 up-regulated and 352 down-regulated. Real-time PCR expression analysis confirmed the microarray data. Singular Enrichment Analysis identified 48 significantly enriched GO terms for molecular functions (28), biological processes (18) and cell components (2). Furthermore, we selected six candidate genes for functional examination by a single-marker association approach, which demonstrated that 20 SNPs in five candidate genes significantly associated with photosynthetic traits, and the phenotypic variance explained by each SNP ranged from 2.3% to 12.6%. This revealed that regulation of photosynthesis by the nuclear genome mainly involves transport, metabolism and response to stimulus functions.
This study provides new genome-scale strategies for the discovery of potential candidate genes affecting photosynthesis in Populus, and for identification of the functions of genes involved in regulation of photosynthesis. This work also suggests that improving photosynthetic efficiency under field conditions will require the consideration of multiple factors, such as stress responses.
田间条件下实际光合速率与潜在光合速率之间的差距表明光合作用有可能得到改善。核基因为提高光合效率提供了可能的靶点。因此，对影响木本植物光合性状的核基因进行全基因组鉴定和表征，将为光合作用的遗传调控提供关键见解，并确定改善光合作用的候选过程。
利用微阵列和混合分离群体分析法，我们在杨树分离群体中鉴定出了与光合性状相关的差异表达核基因。我们在该群体中鉴定出515个差异表达基因（FC≥2或FC≤0.5，P<0.05），其中163个上调，352个下调。实时定量PCR表达分析证实了微阵列数据。单因素富集分析确定了48个在分子功能（28个）、生物学过程（18个）和细胞成分（2个）方面显著富集的GO术语。此外，我们通过单标记关联方法选择了6个候选基因进行功能检测，结果表明5个候选基因中的20个SNP与光合性状显著相关，每个SNP解释的表型变异范围为2.3%至12.6%。这表明核基因组对光合作用的调控主要涉及运输、代谢和对刺激的反应功能。
本研究为发现杨树中影响光合作用的潜在候选基因以及鉴定参与光合作用调控的基因功能提供了新的基因组规模策略。这项工作还表明，在田间条件下提高光合效率需要考虑多种因素，如应激反应。
