K. Dorffling et al., HERITABLE IMPROVEMENT OF FROST TOLERANCE IN WINTER-WHEAT BY IN-VITRO SELECTION OF HYDROXYPROLINE-RESISTANT PROLINE OVERPRODUCING MUTANTS, Euphytica, 93(1), 1997, pp. 1-10
In a previous study (Dorffling et al., J. Plant Physiol. 142, 222-225,
1993) in vitro-selection and regeneration of hydroxyproline (Hyp)-res
istant lines of winter wheat (Triticum aestivum cv. Jo 3063) with incr
eased frost tolerance and increased proline contents was reported. In
this study the heritability of these traits was investigated. The F-1
progenies derived from the pollination of regenerated plants with poll
en from wild type plants developed higher mean frost tolerance (lower
LT(50) values) and higher proline levels compared with in vitro-contro
ls and wild type plants. In the F-2 generation, which was obtained by
self-pollination, segregation of the Hyp-lines in a 3:1 phenotypic rat
io with regard to the traits frost tolerance and proline content was o
bserved. Subsequent selection of extremes in the F-2 yielded homozygou
s plants in the F-3 generation. Lower LT(50) values and increased prol
ine contents in those F-3 plants were significantly correlated. Furthe
rmore, improved frost tolerance of one of the selected mutants was als
o observed in studies with whole plants in the F-4 generation. These r
esults, which are similar to results of parallel studies on winter bar
ley, provide strong evidence for the heritability of the traits 'incre
ased frost tolerance' and 'increased proline content' obtained by this
in vitro-selection procedure. The mutation seems to be due to a singl
e incompletely dominant gene. A comparison of frost tolerance values f
rom F-3 Hyp-progenies with those of seven standard varieties differing
in frost tolerance indicates a considerable improvement of frost tole
rance by the described in vitro-selection method.