School of Biological Sciences and Biotechnology, Minnan Normal University, 36 Xian-Qian-Zhi Street, Zhangzhou, Fujian, 363000, China.
BMC Genomics. 2018 Jan 10;19(1):35. doi: 10.1186/s12864-017-4425-8.
The cytochrome P450 monooxygenases (CYP450, CYP, P450) catalyze numerous monooxygenation/hydroxylation reactions in biochemical pathways. Although CYP superfamily has been systematically studied in a few species, the genome-scale research about it in rice has not been done.
In this study, a total of 355 CYPs encoded by 326 genes were identified in japonica genome. The OsCYP genes are classified into 10 clans including 45 families according to phylogenetic analysis. More than half of the genes are distributed in 53 tandem duplicated gene clusters. Intron-exon structure of OsCYPs exhibits highly conserved and specificity within a family, and divergences of duplicate genes in gene structure result in non-functionalization, neo-functionalization or sub-functionalization. Selection pressure analysis showed that rice CYPs are under purifying selection. The microarray data analysis shows that some genes are tissue-specific expression, such as OsCYP710A5 and OsCYP71X14 in endosperm, OsCYP99A3 and OsCYP78A16 in root and OsCYP93G2 and OsCYP97D7 in leaf. Analysis of RNA-seq data derived from rice leaf developmental gradient indicates that some OsCYPs exhibit zone-specific expression patterns. OsCYP87C2, OsCYP96B5, OsCYP96B8 and OsCYP84A5 were specifically expressed in leaf base and transitional zone. The transcripts of lineages II and IV-1 members were highly abundant in maturing zone. Eighty three OsCYPs are differentially expressed in response to drought stress, of which OsCYP51G3, OsCYP709C9, OsCYP709C5, OsCYP81A6, OsCYP72A18 and OsCYP704A5 are strongly induced and OsCYP78A16, OsCYP89C9 and OsCYP704A5 are down-regulated significantly, and some of the results were validated by qPCR. And 23 up-regulated and 17 down-regulated genes are specific to Osbhlh148 mutation under drought stress. Compared to those in wild type, the changes in transcript levels of several genes are slight in the mutant, such as OsCYP51G3, OsCYP94C2, OsCYP709C9 and OsCYP709C5.
The whole-genomic analysis of rice P450 superfamily provides a clue to understanding biological function of OsCYPs in development regulation and drought stress response, and is helpful to rice molecular breeding.
细胞色素 P450 单加氧酶（CYP450、CYP、P450）在生化途径中催化许多单加氧/羟化反应。尽管 CYP 超家族在少数物种中进行了系统研究，但在水稻中的基因组规模研究尚未进行。
在这项研究中，共鉴定出粳稻基因组中 326 个基因编码的 355 个 CYP。根据系统发育分析，OsCYP 基因分为 10 个族，包括 45 个家族。超过一半的基因分布在 53 个串联重复基因簇中。OsCYP 的内含子-外显子结构在家族内具有高度保守性和特异性，基因结构中重复基因的分歧导致非功能化、新功能化或亚功能化。选择压力分析表明，水稻 CYP 受到纯化选择。微阵列数据分析表明，一些基因在组织中特异性表达，例如胚乳中的 OsCYP710A5 和 OsCYP71X14、根中的 OsCYP99A3 和 OsCYP78A16 以及叶中的 OsCYP93G2 和 OsCYP97D7。来自水稻叶片发育梯度的 RNA-seq 数据分析表明，一些 OsCYPs 表现出区域特异性表达模式。OsCYP87C2、OsCYP96B5、OsCYP96B8 和 OsCYP84A5 在叶片基部和过渡区特异性表达。谱系 II 和 IV-1 成员的转录本在成熟区高度丰富。83 个 OsCYPs 对干旱胁迫表现出差异表达，其中 OsCYP51G3、OsCYP709C9、OsCYP709C5、OsCYP81A6、OsCYP72A18 和 OsCYP704A5 强烈诱导，OsCYP78A16、OsCYP89C9 和 OsCYP704A5 显著下调，部分结果通过 qPCR 验证。在干旱胁迫下，与野生型相比，Osbhlh148 突变体中有 23 个上调和 17 个下调基因特异性表达。与野生型相比，突变体中一些基因的转录水平变化较小，例如 OsCYP51G3、OsCYP94C2、OsCYP709C9 和 OsCYP709C5。
水稻 P450 超家族的全基因组分析为了解 OsCYPs 在发育调控和干旱胁迫响应中的生物学功能提供了线索，有助于水稻的分子育种。
