Stability of Soybean Aphid Resistance in Soybean Across Different Temperatures

Abstract

The soybean aphid (Aphis glycines Matsumura) is the most important insect pest posing a threat to soybean [Glycine max (L.) Merr.] grain production in the United States. Soybean cultivars with resistance are currently being deployed to aid in management of the pest. Temperature has been reported to influence the expression of host plant resistance against crop pests. The objective of this study was to determine if temperatures, 14, 21, and 28°C, altered resistance expression in four aphid‐resistant soybean genotypes, LD05‐16611 (with the Rag1 resistance gene), PI 200538 (Rag2), PI 567541B (rag1c, rag4), and PI 567597C (antixenosis) compared to a susceptible soybean genotype (Williams 82) when challenged with soybean aphid. A replicated no‐choice experiment was conducted and aphid populations of the three soybean aphid biotypes, 1, 2, and 3, were enumerated 14 d after inoculating the five soybean genotypes. Significant interactions were found in the analysis of the effects of temperature, soybean genotype, and aphid biotype on aphid populations. Responses between soybean genotypes and aphid biotypes were consistent with previous reports with the exception of PI 567541B, which had lower resistance against aphid biotype 1 than found in an earlier study. At 14°C, there was limited aphid population growth on all soybean genotypes, including Williams 82. At 21 and 28°C, resistance expression was stable in LD05‐16611 (Rag1), PI 567541B (rag1c, rag4), and PI 567597C (antixenosis), relative to susceptible Williams 82; however, resistance expressed in PI 200538 (Rag2) was significantly stronger at 28°C than at 21°C, as indicated by differences in aphid population size that were found. Results of this study indicated that soybean aphid virulence variability had a stronger influence on the effectiveness of soybean aphid resistance than did temperature, and that the aphid resistance tested in this study would remain stable or be stronger in temperatures ranging between 21 and 28°C.

Effect of Temperature on Plant Resistance to Arthropod Pests

“…However, without a susceptible line as a control, the results are inconclusive. Furthermore, other studies with the soybean aphid (Richardson 2011, Chirumamilla et al 2014 found a decrease, rather than increase, in the expression of resistance at low temperature. The conflicting findings underscore the need for additional research on this crop-pest system using consistent experimental methods and a broad range of temperatures (see Recommendations for Future Research).…”

“…Experiments with biotypes of the soybean aphid on resistant and susceptible soybean lines provide additional evidence that low temperatures suppress plant resistance. Richardson (2011) and Chirumamilla et al (2014) showed that differences in aphid numbers between resistant and susceptible soybeans were smaller at the lowest temperature tested (14°C) compared to higher temperatures (21 and 28°C). In addition, Hough et al (2017) reported a smaller difference in the intrinsic population growth rate of the soybean aphid between resistant and susceptible soybeans at 15°C compared to higher temperatures (20-30°C).…”

“…However, when the reciprocal transfer from 18 to 27°C was done, resistant plants became susceptible in just 1 d. A possible explanation for the slower response for increased resistance may be reduced rates of biochemical changes in plants at lower temperature. Studies with the soybean aphid provide further evidence that temperature-induced changes in plant resistance are reversible when the direction of temperature change is reversed (Richardson 2011, Chirumamilla et al 2014.…”

“…An accumulating body of evidence indicates that a change in temperature elicits changes in plants that alter the expression of resistance to insect pests. In some cases temperature enhances resistance (Sosa 1979, Thindwa and Teetes 1994, Chen et al 2014, Hough 2016, Hough et al 2017; in others it weakens it (Cartwright et al 1946, Hackerott and Harvey 1959, McMurtry 1962, Isaak et al 1963, Kindler and Staples 1970, Wood and Starks 1972, Johnson et al 1980, Salim and Saxena 1991, Walters et al 1991, Harvey et al 1994, Richardson 2011, Chen et al 2014, Chirumamilla et al 2014. And in a few cases, temperature appears to have no effect on plant resistance (Dahms and Painter 1940, Jackai and Inang 1992, Randolph et al 2008.…”

Reduced Fitness of Virulent Aphis glycines (Hemiptera: Aphididae) Biotypes May Influence the Longevity of Resistance Genes in Soybean

“…Furthermore, there may be interactions between abiotic factors, like temperature, on the impact of Rag genes [ 37 , 38 ]. However, the extent that the protection from all Rag genes is influenced by temperature is unknown [ 39 ]. Given these sources of variation in methodology, it is difficult to compare across studies.…”