Comparative Performance of Reniform Nematode Resistant Germplasm Lines

Since 2007, several upland cotton (G. hirsutum) germplasm lines with introgressed resistance to reniform nematode (Rotylenchulus reniformis) have been released for use by the cotton breeding community. At present, four groups of released germplasm lines can be distinguished based on source of resistance and developmental background: (a) the LONREN group, with reniform nematode (RN) resistance derived from G. longicalyx, (b) the BARBREN group with RN resistance derived from wild accession GB-713 of G. barbadense, (c) the M713 group, also with resistance derived from the GB-713 accession but with a different developmental trajectory, and (d) the MT2468 group, with reportedly moderate levels of RN resistance derived from the photoperiodic primitive race accession TX2468 of G. hirsutum. We conducted a comparative study of released germplasm lines from each these four groups, including three lines of the LONREN group, two lines of the BARBREN group, five lines of the M713 group and three lines of the MT2468 group, for a total of 13 RN resistant germplasm lines. Conventional cultivars FM966 and SG747 were included as RN susceptible controls.

Our study was conducted in the field on plots with and without reniform nematode present, and on RN infested outdoor microplots. In addition, an experiment exposing seedlings from each resistant line to various levels of nematode inoculums (0, 1000, 5000, 10,000 and 50,000 RN/150cm³ of autoclaved soil) was conducted under controlled conditions in a greenhouse. Preliminary results indicated that germplasm line BAR 41 of the BARBREN group and all five M713 lines perform well for both resistance and tolerance. Detailed results will be communicated at the Beltwide 2014 meeting.