Pollen grain expression of a gene controlling differences in osmoregulation in wheat leaves: a simple breeding method

The possibility that a gene conditioning differences in osmoregulation in wheat leaves ( or ) is also expressed in pollen grains was investigated in order to differentiate heterozygous and homozygous lines for use in backcross breeding. The difference in osmoregulation in leaves was expressed as a difference in solute accumulation which was calculated from responses of osmotic potential and relative water content to reductions in water potential caused by droughting plants in pots. A corresponding allelic difference was found in pollen grains. It was demonstrated by a difference in relative size, and solute accumulation, after stressing using polyethelene glycol solution. The response occurred only after addition of a small quantity of potassium chloride, and the maximum response occurred at concentrations of approximately =0.2 mM (at least to 10 mM). This suggests that or may condition high affinity potassium transport. Single-gene control was confirmed using pollen responses, and pollen grain expression was further demonstrated by the use of pollen responses, to identify alleles and thus manipulate leaf responses in a backcross breeding study. Because the differences in pollen grain size may be readily observed without measurement using a microscope with relatively low magnification, and because the pollen grains are easily sampled at flowering, the pollen response is suitable as a routine test in plant breeding involving pedigree or backcross methods.