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Development of somatic embryos from morphogenetic cells of the interspecific hybrid Helianthus annuus x Helianthus tuberosus
No full textAcquisition of high embryogenic potential in regenerated plants of Helianthus annuus x H. tuberosus
No full textmesophyll cell defective1, a mutation that disrupts leaf mesophyll differentiation in sunflower
No full textMutants with altered leaf morphology are useful as markers for the study of genetic systems and for probing the leaf
differentiation process. One such mutant with deficient greening and altered development of the leaf mesophyll appeared
in an inbred line of sunflower (Helianthus annuus L.). The objectives of the present study were to determine the
inheritance of the mutant leaf trait and its morphological characterisation. The mutation, named mesophyll cell defective1
(mcd1), has pleiotropic effects and it is inherited as a monogenic recessive. The structure and tissue organization of mcd1
leaves are disrupted. In mcd1 leaves, the mesophyll has prominent intercellular spaces, and palisade and spongy tissues
are not properly shaped. The mutant palisade cells also appear to be more vacuolated and with a reduced number of
chloroplasts than the wild type leaves of equivalent developmental stage. The lamina thickness of mcd1 leaves is greatly
variable and in some areas no mesophyll cells are present between the adaxial and abaxial epidermis. The leaf area of the
mcd1 mutant is extremely reduced as well as the stem height. A deficient accumulation of photosynthetic pigments
characterizes both cotyledons and leaves of the mutant. In mcd1 leaves, chlorophyll (Chl) fluorescence imaging
evidences a spatial heterogeneity of leaf photosynthetic performance. Little black points, which correspond to photosystem
II (PSII) maximum efficiency (Fv/Fm) values close to zero, characterize the mcd1 leaves. Similarly, the lightadapted
quantum efficiency (ΦPSII) values show a homogeneous distribution over wild type leaf lamina, while the
damaged areas in mcd1 leaves, represented by yellow zones, are prominent. In conclusion, the loss of function of the
MCD1 gene in Helianthus annuus is correlated with a variegated leaf phenotype characterized by a localized destruction
of mesophyll morphogenesis and defeat of PSII activity
Epiphylly in a variant of Helianthus annuus x H. tuberosus induced by in vitro tissue culture
No full textOrigin and development in vitro of shoot buds and somatic embryos from intact roots of Helianthus annuus x H. tuberosus
No full textWhite and UV light effects on cell nuclei in the aurea genotype of Lycopersicum esculentum L
No full textA histological study of light-dependent shoot regeneration in hypocotyl explants of tomato cultured in vitro
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