EFFECTS OF CHEMICAL MILIEU ON ATTACHMENT, AGGREGATION, BIOFILM FORMATION, AND VECTOR TRANSMISSION OF XYLELLA FASTIDIOSA STRAINS

• Author(s): Curley, Clytia; Purcell, Alexander; Burr, Thomas; Hoch, Harvey; Lindow, Steven;
• Abstract: An rpfF DSF-deficient mutant that does not adhere to the inside of insect vector mouthparts formed a reduced biofilm in vitro, but contributed to biofilm formation when combined with a wild-type Xylella fastidiosa (Xf)strain. Growth of the DSF-deficient mutant in media PW was comparable to that of the wild type in vitro and neither strain appeared to outcompete the other when grown in PW liquid media over two weeks. However the mutant strain showed reduced growth alone, and in co-culture with the wild-type, in a second medium (BHF) that promoted biofilm formation in the wild-type strain. A fluorescent (gfp) mutant of Temecula was also used on occasion, but was dropped when it became clear that the mutation reduced growth ability in media and plants. Competitive behavior of the various strains in planta is also being investigated in our laboratory. Studies were also undertaken to try to enhance uptake and delivery of Xf from artificial feeding sachets to plants. A wild-type and a DSF-overproducing rpfC mutant strain of Xf were added to sachets and fed to leafhopper vectors. Only one out of 85 insects tested positive for Xf after sachet feeding, and no test grape plants have been infected by Xf from insects fed this way. Wild-type Xf (strain STL), grown on solid media, was also presented for sachet feeding to sharpshooter vectors; one of 24 insects that acquired Xf this way was able to transmit to a healthy seedling.
• Publication Date: Nov 2006
• Journal: 2006 Pierce's Disease Research Symposium