Transition from somatic embryo to friable embryogenic callus in cassava: dynamic changes in cellular structure, physiological status, and gene expression profiles.
Transition from somatic embryo to friable embryogenic callus in cassava: dynamic changes in cellular structure, physiological status, and gene expression profiles.
复制标题
木薯从体细胞胚胎到脆性胚性愈伤组织的转变：细胞结构、生理状态和基因表达谱的动态变化。
DOI：
10.3389/fpls.2015.00824
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发表时间：
2015
影响因子：
5.6
通讯作者：
Zhang P
中科院分区：
文献类型：
--
作者：
Ma Q;Zhou W;Zhang P
脆性胚性愈伤组织是木薯高效遗传转化的最佳材料。FEC诱导的严重基因型依赖性和对体细胞克隆变异的顺从性限制了可靠FEC的产生和维持。识别从体细胞胚胎（SE）到FEC的不同阶段的生物过程中所涉及的关键元素为FEC的改进提供了关键的见解。细胞学观察显示，SE、新鲜FEC（FFEC）和陈旧FEC（OFEC）的亚细胞结构发生了显著变化。OFEC中蔗糖含量减少，果糖和葡萄糖含量增加。通过RNA-seq从SE、FFEC和OFEC中鉴定出总共6871个差异表达基因（DEG）。DEG分析表明，FEC诱导伴随着去分化过程，而表观遗传修饰发生在连续传代过程中。细胞结构被重构，主要包括GO术语“细胞外围”和“外部封装结构”;同时，内部机制也相应发生变化，包括糖酵解的生物学过程和丙氨酸、天冬氨酸和谷氨酸的代谢。OFEC中基因组DNA甲基化的显著降低表明通过染色质修饰改变了基因表达。这些结果表明，FEC的诱导和长期传代是一个复杂的生物学过程，涉及基因组修饰，基因表达和亚细胞重建的变化。本研究结果将有助于提高从农民喜爱的木薯品种木薯到遗传转化的FEC诱导和维持，从而通过基因工程改良木薯。
Friable embryogenic callus (FEC) is considered as the most suitable material for efficient genetic transformation of cassava. Heavy genotype dependence of FEC induction and amenability to somaclonal variation limits the production and maintenance of reliable FEC. Identifying key elements involved in biological processes from somatic embryos (SEs) to FEC at different stages provides critical insights for FEC improvement. Cytological observation showed a dramatic change of subcellular structures among SEs, fresh FEC (FFEC), and old FEC (OFEC). Decrease of sucrose and increase of fructose and glucose were detected in OFEC. A total of 6871 differentially expressed genes (DEGs) were identified from SEs, FFEC, and OFEC by RNA-seq. Analysis of the DEGs showed that FEC induction was accompanied by the process of dedifferentiation, whereas the epigenetics modification occurred during the continuous subculturing process. The cell structure was reconstructed, mainly including the GO terms of “cell periphery” and “external encapsulating structure”; in parallel, the internal mechanisms changed correspondingly, including the biological process of glycolysis and metabolisms of alanine, aspartate, and glutamate. The significant reduction of genomic DNA methylation in OFEC indicated altered gene expression via chromatin modification. These results indicate that the induction and long-term subculture of FEC is a complicated biological process involving changes of genome modification, gene expression, and subcellular reconstruction. The findings will be useful for improving FEC induction and maintenance from farmer-preferred cassava cultivars recalcitrant to genetic transformation, hence improving cassava through genetic engineering.