A PRELIMINARY STUDY ON TRANSMISSION OF PAULOWNIA WITCHES’ BROOM FROM PAULOWNIA TO PERIWINKLE BY DODDER

Periwinkle (Vinca rosea) was first inoculated with the mycoplasma-like organisms (MLO) of paulownia witches' broom from paulownia by southern dodder (Cuscuta australis) in 1986,causing the typical symptoms with yellowish leaves,witches' broom and phyllody of flower parts.The results of the experiment showed that 22 of 77 inoculated plants of periwinkle were diseased and the inoculation periods were 140 to 370 days.The sieve cells of diseased periwinkle with typical phyllody of flower parts,under transmission electron microscope,were full of more MLOs than those of diseased paulownia.They were measured 280-580 nm× 320-860 nm in size,with spherical,elliptical and binary fission,and each was provided with a unit membrance 10 nm in thickness.The MLOs in the ultrathin section of periwinkle were morphologically and ultrastructurally most similar to that of paulownia.they have not been found in healthy periwinkle sample.