RESUMEN
Somaclonal variation arises in plants and animals when differentiated somatic cells are induced into a pluripotent state, but the resulting clones differ from each other and from their parents. In agriculture, somaclonal variation has hindered the micropropagation of elite hybrids and genetically modified crops, but the mechanism responsible remains unknown. The oil palm fruit 'mantled' abnormality is a somaclonal variant arising from tissue culture that drastically reduces yield, and has largely halted efforts to clone elite hybrids for oil production. Widely regarded as an epigenetic phenomenon, 'mantling' has defied explanation, but here we identify the MANTLED locus using epigenome-wide association studies of the African oil palm Elaeis guineensis. DNA hypomethylation of a LINE retrotransposon related to rice Karma, in the intron of the homeotic gene DEFICIENS, is common to all mantled clones and is associated with alternative splicing and premature termination. Dense methylation near the Karma splice site (termed the Good Karma epiallele) predicts normal fruit set, whereas hypomethylation (the Bad Karma epiallele) predicts homeotic transformation, parthenocarpy and marked loss of yield. Loss of Karma methylation and of small RNA in tissue culture contributes to the origin of mantled, while restoration in spontaneous revertants accounts for non-Mendelian inheritance. The ability to predict and cull mantling at the plantlet stage will facilitate the introduction of higher performing clones and optimize environmentally sensitive land resources.
Asunto(s)
Arecaceae/genética , Metilación de ADN , Epigénesis Genética/genética , Epigenómica , Genoma de Planta/genética , Fenotipo , Retroelementos/genética , Alelos , Empalme Alternativo/genética , Arecaceae/metabolismo , Frutas/genética , Genes Homeobox/genética , Estudios de Asociación Genética , Intrones/genética , Datos de Secuencia Molecular , Aceite de Palma , Aceites de Plantas/análisis , Aceites de Plantas/metabolismo , Sitios de Empalme de ARN/genética , ARN Interferente Pequeño/genéticaRESUMEN
We report the successful culture of oil palm (Elaeis guineensis Jacq.) suspension cells in a bioreactor. In vitro propagation of this perennial monocotyledonous tree is an important part of the oil palm industry's approach to clonal propagation of high-yielding accessions. During culture of oil palm cells in a batch bioreactor, nutrients and extracellular metabolites were monitored, and kinetic parameters and nutrient-to-biomass conversion yields were calculated. The biomass increased approximately 3.5-fold per month, consistent with values reported for shake flask cultures. Although the carbon source was completely depleted by the end of the run, nitrogen sources remained in large excess and the sugar-to-biomass conversion yield remained low. Linear growth indicated that the cells were limited. The results obtained from the bioreactor runs indicated that we should be able to improve biomass production by carrying out optimization studies. Therefore, we initiated multi-factorial analyses using response surface experimental designs to investigate the effects of different nitrogen sources, as well as inoculum size and conditioned medium, on biomass production in flask cultures. Whereas glutamine does not have a significant effect on biomass production, ammonia has a positive effect up to an optimum concentration. Both inoculum density and conditioned medium have positive, synergistic effects on biomass production.
