Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 12, 2000
Publication Date: January 30, 2000
Technical Abstract: The cotton root-knot nematode, Meloidogyne incognita, and the reniform nematode Rotylenchulus reniformis, are the most damaging nematodes to Upland cotton production in the United States and most other cotton-growing areas of the world. Management options are marginally cost effective. No useful level of resistance to R. reniformis has been bred into Upland cotton. The strategy we tested to develop nematode resistant cotton germplasm was originally developed at North Carolina State University for use in tobacco. This strategy involved the use of transgenes designed to prevent giant cell/syncytia development or ablate giant cells/syncytia as they form. The Nematode Responsive Element (NRE) from the promoter from TobRB7 was linked to a Barnase coding sequence (modified in the 5' leader sequence to attenuate translational capability of the transcript) for genetic ablation and to an antisense cotton homologue (TIP) of TobRB7 for developmental arrest of giant cell/syncytia formation. These constructs were introduced into cotton and the resultant transgenic lines were screened for resistance to M. incognita. Putative resistant lines were selfed and the R1 progeny subjected to a comprehensive assay for resistance to both M. incognita and R. reniformis allowing us to obtain a statistically sound measure and comparison of resistance. Six NRE- AttBarnase lines and 8 NRE-AntiTIp cotton lines exhibited resistance to root-knot nematode parasitism in the initial screen. The more comprehensive R1 assays revealed that only one of NRE-AttBarnase lines retained resistance in the R1 generation. The observed level of resistance however, was not as great as that seen in existing root-knot nematode resistant cotton germplasm. None of the lines exhibited resistance to R. reniformis.