SOMATIC HYBRIDIZATION WITH APHOTOTROPIC MUTANTS OF THE MOSS CERATODONPURPUREUS - GENOME SIZE, PHYTOCHROME PHOTOREVERSIBILITY, TIP-CELL PHOTOTROPISM AND CHLOROPHYLL REGULATION
T. Lamparter et al., SOMATIC HYBRIDIZATION WITH APHOTOTROPIC MUTANTS OF THE MOSS CERATODONPURPUREUS - GENOME SIZE, PHYTOCHROME PHOTOREVERSIBILITY, TIP-CELL PHOTOTROPISM AND CHLOROPHYLL REGULATION, Journal of plant physiology, 153(3-4), 1998, pp. 394-400
This paper describes somatic fusion of protoplasts in the moss Ceratod
on purpureus, specifically of the phototropic mutants ptr103 and ptr11
6. Phototropism of Ceratodon filaments is phytochrome mediated. The pt
r116 mutant is thought to carry a lesion in the biosynthetic pathway o
f the phytochrome chromophore; this mutant grows negatively gravitropi
cally in continuous unilateral red light. The ptr103 mutation is thoug
ht to effect phytochrome signal transduction: the phenotype of this mu
tant is clearly distinguishable from wildtype and ptr116 because filam
ents grow in random directions in continuous unilateral red. Following
protoplasting and PEG-mediated protoplast fusion with ptr103 and ptr1
16, lines with a wildtype-like phenotype were identified, propagated a
nd tested for genome size and phytochrome physiology. The 1C genome si
ze of Ceratodon is estimated to lie between 240 and 270 Mbp, based on
comparisons with Arabidopsis thaliana (genome size 100 Mbp). The genom
e size of one line that arose from a fusion experiment, Ptr103(+)ptr11
6, was shown by flow cytometry to be ca. twice that of the wildtype. W
ith respect to phytochrome spectral activity, phototropism and regulat
ion of chlorophyll synthesis, ptr103(+)ptr116 was similar to the wildt
ype. These data are consistent with ptr103(+)ptr116 being a bona fide
somatic fusion product in which each mutant parent complements a reces
sive genetic lesion of the other.