Post-infection development of reniform nematode on resistant soybean lines JTN-5203, PI 404166, and 02011-126-1-5-1-1

Authors: Stetina, Salliana - Sally; Smith, James - Rusty; Ray, Jeffery - Jeff

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/9/2019
Publication Date: 9/17/2019
Citation: Stetina, S.R., Smith, J.R., Ray, J.D. 2019. Post-infection development of reniform nematode on resistant soybean lines JTN-5203, PI 404166, and 02011-126-1-5-1-1. Meeting Abstract. 51:40. https://doi.org/10.21307/jofnem-2019-065.
DOI: https://doi.org/10.21307/jofnem-2019-065

Interpretive Summary:

Technical Abstract: Soybean growers in the southeastern U.S. are faced with the challenge of producing a profitable crop in fields infested with reniform nematode (Rotylenchulus reniformis). The soybean lines JTN-5203, PI 404166, and 02011-1-1-5-1-1 were previously identified as supporting a lower level of root infection by reniform nematode than susceptible soybean lines, but information on post-infection effects on the nematode was lacking. Therefore, the objective of this study was to characterize post-infection development and fecundity in these resistant lines. In three growth chamber experiments using these lines and the susceptible control cultivar Braxton, nematode development early and late in the infection cycle and nematode fecundity were assessed. In each experiment seeds were planted into containers filled with 120 cm3 of a steam-pasteurized soil mix (1 sandy loam soil:2 sand). Upon stand establishment, 500 reniform nematodes (mixed vermiform life stages) were added to the soil in each container. A completely randomized design with 10 replications was used for each experiment, and experiments were conducted twice. To assess nematode development early in the infection cycle, root infection on 10 plants of each soybean line was measured at 2-day intervals through day 10. Assessment of nematode development late in the infection cycle began 15 days after inoculation (DAI) and continued at 5-day intervals through day 30. In both development experiments, root-associated nematodes were classified as either vermiform, swelling (enlargement of body but not yet assuming the kidney-shape characteristic of this species), reniform (kidney-shaped female without egg mass), or gravid (kidney-shaped female with egg mass). Nematode fecundity was measured using plants collected at the 25- and 30-day intervals. Up to 50 arbitrarily selected gravid females were hand-picked from each soybean line, and the number of eggs were counted after crushing the female under a cover slip on a glass slide. There was a slight (1 or 2 day) delay in root infection on the resistant lines as compared to Braxton. Delayed development was noted as early as 10 DAI, with 50% of the population on Braxton classified as gravid while only 20% to 25% of the nematodes in populations developing on the resistant lines had begun laying eggs. The resistant line 02011-1-1-5-1-1 maintained a higher percentage of nematodes in the swelling phase of development late into the infection cycle as compared to JTN-5203 and PI 404166. All three of the resistant soybean lines produced significantly fewer eggs per female compared to Braxton, with a 68 to 95% reduction at 25 DAI, and 80 to 98% reduction at 30 DAI. Thus, it appears that the post-infection mechanisms contributing to resistance in these lines include delayed infection, slower development, and reduced reproduction. The greatly delayed development in 02011-1-1-5-1-1 suggests this line has different or additional mechanisms contributing to reniform nematode resistance as compared to JTN-5203 and PI 404166.