Jaligot E., Beulé T., Rival A.
UMR 1098 Biologie du Développement des Plantes Pérennes, CIRAD-CP/IRD, Centre IRD, 911 avenue Agropolis, B.P. 5045, 34032 Montpellier Cedex 01, France,
Theor Appl Genet. 2002 Jun;104(8):1263-1269. doi: 10.1007/s00122-002-0906-4. Epub 2002 Apr 26.
The occurrence of "mantled" somaclonal variants (approx. 5%), which display alterations in floral organ structure, among populations of somatic embryo-derived oil palms ( Elaeis guineensis Jacq.) currently hampers any scaling-up of clonal plant micropropagation. As a first step towards the identification of abnormality-discriminating markers, we have screened a set of 27 oil palm cDNA probes for methylation-sensitive restriction fragment length polymorphisms (RFLPs) using callus genomic DNA digested with the isoschizomeric enzymes MspI and HpaII. Only two probes (CPHO62 and -63) were found to differentiate reproducibly in two different genotypic backgrounds between nodular compact calli (NCC) and fast-growing calli (FGC), which generate 5% and 100% "mantled" plantlets, respectively. Comparative analyses were then conducted on DNA from inflorescences and leaves of normal and abnormal adult regenerants. With both probes, the observed methylation patterns were strongly clone-dependent and monomorphic with respect to the phenotype of the regenerants, except for the type-specific banding pattern obtained with the CPHO62 probe on material from the LMC3 clonal offspring. The results presented here mirror the higher difference in genomic DNA methylation observed between normal and abnormal embryogenic calli when compared to more differentiated plant material. Moreover, they reinforce the paramount interest of NCC and FGC callus lines as a material of choice in the search for early epigenetic markers of the "mantled" somaclonal variation. The potential use of methylation-sensitive RFLPs for the early detection of somaclonal variation at early stages of the micropropagation process is discussed.
在体细胞胚胎衍生的油棕（Elaeis guineensis Jacq.）群体中出现的“披被状”体细胞克隆变异体（约5%），其花器官结构发生改变，目前阻碍了克隆植物微繁殖的任何扩大规模。作为鉴定异常鉴别标记的第一步，我们使用经同裂酶MspI和HpaII消化的愈伤组织基因组DNA，筛选了一组27个油棕cDNA探针，用于甲基化敏感限制性片段长度多态性（RFLP）分析。仅发现两个探针（CPHO62和 -63）能够在两种不同基因型背景下，在结节状紧密愈伤组织（NCC）和快速生长愈伤组织（FGC）之间可重复地区分，这两种愈伤组织分别产生5%和100%的“披被状”植株。然后对正常和异常成年再生植株的花序和叶片DNA进行了比较分析。对于这两个探针，观察到的甲基化模式强烈依赖克隆，并且对于再生植株的表型是单态的，除了用CPHO62探针在LMC3克隆后代材料上获得的类型特异性条带模式。与更分化的植物材料相比，这里呈现的结果反映了正常和异常胚性愈伤组织之间观察到的基因组DNA甲基化差异更大。此外，它们强化了NCC和FGC愈伤组织系作为寻找“披被状”体细胞克隆变异早期表观遗传标记的首选材料的至关重要性。讨论了甲基化敏感RFLP在微繁殖过程早期阶段体细胞克隆变异早期检测中的潜在用途。
