Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Leiden, Netherlands.
Sanquin Plasma Products B.V., Amsterdam, Netherlands.
Nat Commun. 2021 May 4;12(1):2508. doi: 10.1038/s41467-021-22815-8.
Plant somatic cells can be reprogrammed into totipotent embryonic cells that are able to form differentiated embryos in a process called somatic embryogenesis (SE), by hormone treatment or through overexpression of certain transcription factor genes, such as BABY BOOM (BBM). Here we show that overexpression of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED 15 (AHL15) gene induces formation of somatic embryos on Arabidopsis thaliana seedlings in the absence of hormone treatment. During zygotic embryogenesis, AHL15 expression starts early in embryo development, and AH15 and other AHL genes are required for proper embryo patterning and development beyond the globular stage. Moreover, AHL15 and several of its homologs are upregulated and required for SE induction upon hormone treatment, and they are required for efficient BBM-induced SE as downstream targets of BBM. A significant number of plants derived from AHL15 overexpression-induced somatic embryos are polyploid. Polyploidisation occurs by endomitosis specifically during the initiation of SE, and is caused by strong heterochromatin decondensation induced by AHL15 overexpression.
植物体细胞可以通过激素处理或过表达某些转录因子基因（如 BABY BOOM [BBM]）被重编程为全能胚胎细胞，从而在体细胞胚胎发生（SE）过程中形成分化的胚胎。在这里，我们表明，过表达 AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED 15（AHL15）基因可以在没有激素处理的情况下诱导拟南芥幼苗形成体细胞胚胎。在合子胚胎发生过程中，AHL15 的表达在胚胎发育的早期开始，并且 AH15 和其他 AHL 基因对于适当的胚胎模式形成和超过球形阶段的发育是必需的。此外，AHL15 和其几个同源物在激素处理时被上调并被需要用于 SE 的诱导，并且它们作为 BBM 的下游靶标对于有效的 BBM 诱导的 SE 是必需的。许多源自 AHL15 过表达诱导的体细胞胚胎的植物是多倍体。多倍体化通过有丝分裂发生，特别是在 SE 的起始时，并且是由 AHL15 过表达诱导的强烈异染色质去凝聚引起的。
