New Disease Reports (2005) 11, 15.

An isolate of 'Candidatus Phytoplasma australiense' group associated with Nivun-Haamir-Die Back disease of papaya in Israel

A. Gera 1*, M. Mawassi 1, M. Zeidan 2, S. Spiegel 1 and M. Bar-Joseph 3

*abedgera@volcani.agri.gov.il

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Accepted: 29 Mar 2005

Papaya (Carica papaya) plants grown in Israel were severely damaged by a disease named Nivun Haamir die-back (NHDB) (Franck & Bar-Joseph, 1992). Symptoms of NHDB resembled those of Australian papaya die-back (PpDB) associated with Ca.Phytoplasma australiense (Liu et al., 1996; White et al., 1998) (Fig. 1). Field observations of NHDB, suggested an airborne pathogen, but electron microscopy studies failed to associate it with a phytoplasma (Franck & Bar-Joseph, 1992).

Recently, 15 papaya plants suspected of having NHDB were tested for phytoplasma by nested PCR using P1/P7 and R16F2n/R16R2 primers. Phytoplasma products were confirmed by direct sequencing of the 16S/23S spacer region (SR), where 9 out of 15 samples with symptoms tested positive but all healthy controls were negative. Grapevines (Vitis vinifera), with symptoms of leaf rolling and red colouration, growing close to the papaya plots, were also tested and found positive. The SR sequences (851bp) from papaya (GenBank Accession No. AY903951) and grapevine were identical. When compared with other phytoplasmas these sequences showed the highest similarity with phytoplasmas from the 16SrXII Stolbur group; Stolbur-Ph-Lily (AY169309) 97.66%; Sugarcane phytoplasma -Mauritius strain (AJ539181) 97.65%; grapevine yellows Germany (VK) (X76428) 97.54%; Australian grapevine yellows (AGY) (X95706) and Phormium yellow leaf (PYL) (U43569) 96.48%. This is the first report of the association between NHDB and a Ca. Phytoplasma australiense isolate. The high degree of similarity between the NHDB-associated phytoplasma and that infecting grapes suggests a common inoculum source and probably a common vector. The use of papaya plants as indicators for gaining epidemiological information on the temporal spread of the phytolasmas to vineyards is under investigation.


References

  1. Franck A, Bar-Joseph M, 1992. Use of netting and white wash spray to protect papaya plants against Nivun-Haamir (NH)-die back diseased. Crop Protection 11, 525-528.
  2. Liu BD, White DT, Walsh KB, Scott PT, 1996. Detection of phytoplasmas in dieback, yellow crinkle and mosaic disease of papaya using polymerase chain reaction techniques. Australian Journal of Agricultural Research 47, 387-349.
  3. White DT, Blackall LL, Scott PT, Walsh KB, 1998. Phylogenic positions of phytoplasmas associated with dieback, yellow crinkle and mosaic disease of papaya, and their proposed inclusion in Candidatus Phytoplasma Australiense and new taxon, Candidatus Phytoplasma Australasia. International Journal of Systematic Bacteriology 48, 941-951.

This report was formally published in Plant Pathology

©2005 The Authors