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Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/2/2015 Publication Date: 12/1/2015 Citation: Stetina, S.R. 2015. Postinfection development of Rotylenchulus reniformis on resistant Gossypium barbadense accessions. Journal of Nematology. 47:302-309. Interpretive Summary: The reniform nematode, a microscopic worm that feeds on plant roots, causes significant cotton losses in the United States. Researchers developed breeding lines with resistance from two relatives of cotton, Gossypium barbadense accession GB 713 and G. barbadense cultivar TX 110. Only a few reniform nematodes can successfully infect the roots of these resistant lines, but little is known about how the resistance affects nematode development and reproduction after infection. Unique reniform nematode developmental patterns were noted on each of the resistant cotton lines and the susceptible cotton cultivar Deltapine 16. Progression to the mature adult and egg-laying stages of development was fastest on susceptible cotton, delayed on G. barbadense cultivar TX 110, and slowest on G. barbadense accession GB 713. Egg production by individual nematodes infecting the three cotton lines was similar, suggesting that resistance did not inhibit nematode reproduction. This study is the first report of delayed reniform nematode development associated with G. barbadense accession GB 713. The different nematode developmental patterns in the resistant cotton lines identified in this study have implications for developing and deploying resistance; it may be possible to combine the two types of unique resistance into a single cotton cultivar, or develop separate cultivars that growers can rotate to suppress the reniform nematode population. Technical Abstract: The reniform nematode (Rotylenchulus reniformis) causes significant cotton (Gossypium hirsutum) losses in the midsouthern United States. The research objective was to describe the effects of two resistant G. barbadense lines (cultivar TX 110 and accession GB 713) on development and fecundity of reniform nematode. Nematode development and fecundity were evaluated on the resistant lines and susceptible G. hirsutum cultivar Deltapine 16 in three repeated growth chamber experiments. Nematode development on roots early and late in the infection cycle was measured at set intervals from 1 to 25 days after inoculation (DAI), and genotypes were compared based on the number of nematodes in four developmental stages (vermiform, swelling, reniform, gravid). At 15, 20 and 25 DAI, egg production by individual females parasitizing each genotype was measured. Unique reniform nematode developmental patterns were noted on each of the cotton genotypes. During the early stages of infection, development occurred one day faster on susceptible cotton than on the resistant genotypes. Later, progression to the reniform and gravid stages of development occurred first on the susceptible genotype, followed by G. barbadense cultivar TX 110, and finally G. barbadense accession GB 713. Egg production by nematodes infecting the three genotypes was similar. This study corroborates delayed development previously reported on G. barbadense cultivar TX 110, and is the first report of delayed development associated with G. barbadense accession GB 713. The different developmental patterns in the resistant genotypes suggest that unique or additional loci may confer resistance in these two lines. |
