Physiological activity of free auxins in aneuploid wheat lines

The coleoptile test was used to assess the activities of free auxins at til lering and heading stages in 32 aneuploid wheat (Triticum aestivum L., cv. Chinese Spring) lines, including ditelosomic, tetrasomic, and nullisomic-te trasomic lines in the homoeologous chromosome groups 2-4 and the 2R, 2H, 3R , 4R, and 4H addition lines. The loss of particular chromosome arms and the addition of extra chromosomes affected auxin activities, and we presume th at these chromosomes comprise the genes in control of auxin content in whea t tissues. In particular, the chromosome arm 2DL comprises the gene positiv ely affecting the auxin content, whereas the chromosomes 2AS, 2B, 3D, and 4 B contain the genes exerting the inhibiting effect. The effect of the genes located on 2A and 2D was dosage-dependent and species-specific: the homoel ogous chromosomes of wheat, rye, and barley, when added to a euploid wheat chromosome set, produced different effects. The compensatory effect of homo elogous chromosomes varied in nullisomic-tetrasomic lines: the best compens ation was observed in the N3AT3B, N4AT4B, and N4BT4D lines at the tillering stage and in the N3AT3D, N3DT3A, and N3BT3D at the heading stage.