Self-fertile cybrids nicotiana tabacum (+hyoscyamus aureus) with a nucleo-plastome incompatibility

Cytoplasmic hybrids (cybrids) in a novel inter-generic combination, Nicotiana tabacum (+Hyoscyamus aureus), were generated by fusion of protoplasts from a plastome tobacco albino mutant (line R100a1) and %-irradiated green protoplasts of H. aureus. Cybrids possessed a plastome of H. aureus and a rearranged mitochondrial DNA. The cybrids displayed a syndrome of nucleo-plastome incompatibility expressed as a partial chlorophyll-deficiency of cotyledonary and true leaves at the early stage of vegetative development of plants grown from seeds in soil. During later development, the plants restored a normal green coloration. This character is phenotypically indistinguishable from the same syndrome in previously generated cybrids N. tabacum (+H. nigrum). In contrast to the cybrids N. tabacum (+H. nigrum), cybrids N. tabacum (+H. aureus) were self-fertile, and did not manifest other features that were interpreted as nucleo-mitochondrial incompatibilities in N. tabacum (+H. nigrum) plants. Therefore, the cybrids N. tabacum (+H. aureus) present a self-propagating system of Nicotiana (+Hyoscyamus) nucleo-plastome incompatibility in its pure form

New CMS-associated phenotypes in cybrids nicotiana tabacum L. (+Hyoscyamus niger L.).

Morphological characteristics were studied in cytoplasmic male sterile (CMS) cybrids possessing the tobacco nuclear genome, Hyoscyamus niger plastome and recombinant mitochondria. After backcrosses with tobacco, new flower modifications were found, including: conversions of stamens into branched filamentous structures; alterations in the shape of petals and the corolla limb; and high degrees of reduction in most flower organs. Vegetative alterations (leaf elongation and stem branching) occurred in some cybrids. Results confirmed that a protoplast fusion-based alloplasmic cytoplasm transfer, followed by conventional backcrosses, is a useful tool for generating alternative CMS sources with novel nucleo-cytoplasmic compositions. These alterations in the genetic status were accompanied by modified floral and vegetative phenotypes

Extensive developmental and metabolic alterations in cybrids nicotiana tabacum (+ hyoscyamus niger) are caused by complex nucleo-cytoplasmic incompatibility

The genetic basis of multiple phenotypic alterations was studied in cell-engineered cybrids Nicotiana tabacum (+ Hyoscyamus niger) combining the nuclear genome of N. tabacum, plastome of H. niger and recombinant mitochondria. The plants possess a complex, maternally inheritable syndrome of nucleo-cytoplasmic incompatibility, severely affecting growth, metabolism and development. In vivo, the syndrome was manifested as: late germination of seeds; dramatic decrease of chlorophyll and carotenoids in cotyledons and leaves; altered morphology of cotyledons, leaves and flowers; and dwarfism. The leaf phenotype depended on light intensity. In 'green flowers' (an extreme phenotype), homeotic function B was downregulated. In vitro, the incompatibility syndrome was restricted to the pigment deficiency of cotyledons. Electron microscopy revealed perturbations in the differentiation of chloroplasts and palisade parenchyma cells in bleached leaves. The pigment deficiency accompanied by retarded growth is discussed as a result of plastome–genome incompatibility, whereas other features are likely to be due to nucleo-mitochondrial incompatibilities