Development of Rotylenchulus reniformis differs on resistant Gossypium arboreum lines A2-354 and A2-690

Authors: Stetina, Salliana - Sally

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 8/6/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Gossypium arboreum lines A2-354 and A2-690 were previously reported to be resistant to the reniform nematode (Rotylenchulus reniformis). In two repeated growth chamber experiments, with susceptible G. hirsutum cultivar Deltapine 16 as a control, the effects of these lines on reniform nematode development and fecundity were examined. Genotypes were compared based on the number of nematodes on plant roots in four stages of development (vermiform, swelling, reniform, gravid) at 2-day intervals from 4 to 8 days after inoculation (DAI), and at 5-day intervals from 10 to 30 DAI. Egg production by individual females parasitizing each genotype was measured at 25 and 30 DAI. Throughout the experiment, fewer nematodes developed on the two G. arboreum lines than on the susceptible G. hirsutum cultivar, confirming earlier reports of resistance. Progression to the gravid stage of development occurred first on the susceptible genotype Deltapine 16 (6 DAI), followed by A2-690 (8 DAI), and finally A2-354 (10 DAI). The rate of progression from the swelling to the reniform stage of development differed among the genotypes. Most individuals in the root-associated nematode population were classified in the reniform stage of development at 8 DAI for Deltapine 16 and A2-354, but this wasn’t true for A2-690 until 15 DAI. Progression from the reniform to the gravid stage of development was more synchronous, with most of the nematode population on all three genotypes classified in this stage at 25 DAI. There were no consistent significant differences in egg production by nematodes infecting the three genotypes. In the first test, there were no differences among the genotypes at 25 DAI, but Deltapine 16 produced more eggs per female (46.6) than A2-690 (28.9) at 30 DAI. In this test, there were no gravid females observed in the subset of A2-354 plants harvested at 30 DAI, so no egg counts were possible for this line. However, in the second test all three genotypes had gravid females at both 25 and 30 DAI, and A2-690 supported production of the most eggs per female (33.4) at 25 DAI. Deltapine 16 and A2-354 produced fewer eggs per female at 25.9 and 23.0, respectively, although these two genotypes did not differ from each other. No significant differences in egg production occurred at 30 DAI in the second test. The slower development could work in conjunction with reduced numbers of infections to help suppress the reniform nematode population. This study is the first report of delayed development associated with G. arboreum lines A2-354 and A2-690.