Abstract
Alloplasmic wheat having Ae. geniculata or Ae. mutica cytoplasm showed delayed flowering-time compared with euplasmic lines with normal cytoplasm. Flowering-time is determined by three characteristics, that is, vernalization requirement, photoperiodic sensitivity and narrow-sense earliness. The growth analysis using a growth chamber revealed that the alloplasmic lines showed higher vernalization requirement and delayed narrow-sense earliness compared with the euplasmic lines, resulting in increased leaf number. In the euplasmic lines, expression of flowering promoter genes, VRN1 and WFT, were detected at the 5-leaf stage, when the growth stage transits from vegetative to reproductive phase, and continued at the reproductive growth phase. On the other hand, VRN1 and WFT were expressed at later stage in the alloplasmic lines, and the expression levels were lower than those in the euplasmic lines. These results indicate that the delayed flowering-time in the alloplasmic lines is caused by the alteration of flowering-time genes controlled by the mitochondrial retrograde signaling.
