Qualitative Distribution of Candidatus Phytoplasma Oryzae in Roots, Stems and Leave of Napier Grass (Pennisetum purpureum)

For sustainable production of Napier grass ( Pennisetum purpureum ), screening for the absence of phytoplasma on propagation material (stem) is carried by Nested-PCR in detection of 16S rDNA on leaves.  However, the aim of this study was to investigate if there is uneven distribution of the pathogen in roots, stems and leaves of the infected plants that could influence screening results. A total of 294 Napier grasses infected with candidatus phytoplasma oryzae were sampled from western Kenya for detection of Napier Stunt Disease (Phytoplasma Oryzae) by nested PCR. There was significant difference on distribution of phytoplasma in roots, stems and leaves (F=36.26, df=2, p<0.001). The results show that high number of positive samples were detected from stem (94.1 %), leaves (77 %) and roots (44.1 %) samples, respectively. Conclusively, the study revealed uneven distribution thus inclusion of stem samples should be considered during screening procedures. Other factors like seasonal variation are also essential to be studied. Keywords : Phytoplasma, Napier grass, nested PCR, Distribution of the pathogen, Propagation