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 greater than or equal to 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.