27 research outputs found
Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates.
Vegetative segregation of a mixed plastid population
in protoplast fusion-derived cell lines can be directed
by a selection favouring the multiplication of one
of the parental plastid types. This report defines some of
the critical conditions leading to a homogeneous plastid
population in cybrid plants generated by protoplast fusion
between Nicotiana plumbaginifolia and an albino
and streptomycin-resistant N. tabacum plastid mutant.
Light (1,500 Ix) conferred a strong selective advantage to
chloroplasts versus albino plastids, while the lack of this
effect in dim light (300 Ix) indicated that a sufficient light
intensity is essential to the phenomenon. Selection on
streptomycin-containing medium in the dark, however,
led to the preferential multiplication of resistant plastids.
Streptomycin selection of resistant chloroplasts in the
light, consequently, results in a plastid selection of doubled
stringency. In another experiment a definite, but leaky,
selection for chloroplast recombination (selection for
greening on streptomycin-containing medium in dim
light) was used to reveal various recombination products.
Protoplast fusion in fact resulted in cybrid plants showing
only simple chimeric segregation of unchanged
parental plastids. These results demonstrate the essential
requirement for stringent plastid selection, as defined by
cell culture conditions, to precede the formation of
shoots expected to possess the desired plastid genetic
composition
Gene trapping with firefly luciferase in Arabidopsis. Tagging of stress-responsive genes
Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates.
Vegetative segregation of a mixed plastid population
in protoplast fusion-derived cell lines can be directed
by a selection favouring the multiplication of one
of the parental plastid types. This report defines some of
the critical conditions leading to a homogeneous plastid
population in cybrid plants generated by protoplast fusion
between Nicotiana plumbaginifolia and an albino
and streptomycin-resistant N. tabacum plastid mutant.
Light (1,500 Ix) conferred a strong selective advantage to
chloroplasts versus albino plastids, while the lack of this
effect in dim light (300 Ix) indicated that a sufficient light
intensity is essential to the phenomenon. Selection on
streptomycin-containing medium in the dark, however,
led to the preferential multiplication of resistant plastids.
Streptomycin selection of resistant chloroplasts in the
light, consequently, results in a plastid selection of doubled
stringency. In another experiment a definite, but leaky,
selection for chloroplast recombination (selection for
greening on streptomycin-containing medium in dim
light) was used to reveal various recombination products.
Protoplast fusion in fact resulted in cybrid plants showing
only simple chimeric segregation of unchanged
parental plastids. These results demonstrate the essential
requirement for stringent plastid selection, as defined by
cell culture conditions, to precede the formation of
shoots expected to possess the desired plastid genetic
composition
Impact of the stringency of cell selection on plastid segregation in protoplast fusion-derived Nicotiana regenerates.
Vegetative segregation of a mixed plastid population
in protoplast fusion-derived cell lines can be directed
by a selection favouring the multiplication of one
of the parental plastid types. This report defines some of
the critical conditions leading to a homogeneous plastid
population in cybrid plants generated by protoplast fusion
between Nicotiana plumbaginifolia and an albino
and streptomycin-resistant N. tabacum plastid mutant.
Light (1,500 Ix) conferred a strong selective advantage to
chloroplasts versus albino plastids, while the lack of this
effect in dim light (300 Ix) indicated that a sufficient light
intensity is essential to the phenomenon. Selection on
streptomycin-containing medium in the dark, however,
led to the preferential multiplication of resistant plastids.
Streptomycin selection of resistant chloroplasts in the
light, consequently, results in a plastid selection of doubled
stringency. In another experiment a definite, but leaky,
selection for chloroplast recombination (selection for
greening on streptomycin-containing medium in dim
light) was used to reveal various recombination products.
Protoplast fusion in fact resulted in cybrid plants showing
only simple chimeric segregation of unchanged
parental plastids. These results demonstrate the essential
requirement for stringent plastid selection, as defined by
cell culture conditions, to precede the formation of
shoots expected to possess the desired plastid genetic
composition
A mutant of Nicotiana sylvestris deficient in serine glyoxylate aminotransferase activity
Inactivation of Plasma Membrane-Localized CDPK-RELATED KINASE5 Decelerates PIN2 Exocytosis and Root Gravitropic Response in Arabidopsis.
CRK5 is a member of the Arabidopsis thaliana Ca2+/calmodulin-dependent kinase-related kinase family. Here, we show that inactivation of CRK5 inhibits primary root elongation and delays gravitropic bending of shoots and roots. Reduced activity of the auxin-induced DR5-green fluorescent protein reporter suggests that auxin is depleted from crk5 root tips. However, no tip collapse is observed and the transcription of genes for auxin biosynthesis, AUXIN TRANSPORTER/AUXIN TRANSPORTER-LIKE PROTEIN (AUX/LAX) auxin influx, and PIN-FORMED (PIN) efflux carriers is unaffected by the crk5 mutation. Whereas AUX1, PIN1, PIN3, PIN4, and PIN7 display normal localization, PIN2 is depleted from apical membranes of epidermal cells and shows basal to apical relocalization in the cortex of the crk5 root transition zone. This, together with an increase in the number of crk5 lateral root primordia, suggests facilitated auxin efflux through the cortex toward the elongation zone. CRK5 is a plasma membrane-associated kinase that forms U-shaped patterns facing outer lateral walls of epidermis and cortex cells. Brefeldin inhibition of exocytosis stimulates CRK5 internalization into brefeldin bodies. CRK5 phosphorylates the hydrophilic loop of PIN2 in vitro, and PIN2 shows accelerated accumulation in brefeldin bodies in the crk5 mutant. Delayed gravitropic response of the crk5 mutant thus likely reflects defective phosphorylation of PIN2 and deceleration of its brefeldin-sensitive membrane recycling