Resistance to greenbugs in the sorghum nested association mapping population

Abstract

The greenbug, Schizaphis graminum, is a serious pest of sorghum (Sorghum bicolor). For the past several decades, resistant sorghum hybrids have been used to control greenbug populations. However, the durability of plant resistance is frequently challenged by evolution of new greenbug biotypes, and there is a continuous need for screening of resistant germplasm for its effective management in the field. Natural variation in sorghum plants/populations provides distinct approaches to identify novel sources of resistance against greenbugs. In this study, we used the recently developed sorghum nested association mapping (NAM) population parental lines to understand sources of sorghum resistance to greenbugs. Using choice and no-choice assays, we have identified SC265 and Segaolane as the resistant and susceptible lines, respectively, to greenbugs compared to the wild-type plants. The Electrical Penetration Graph (EPG) analysis revealed that the greenbugs spent significantly lesser time in the xylem and sieve element phases while feeding on the resistant NAM parental line, SC265, compared to the susceptible (Segaolane) and wild-type (RTx430) sorghum lines. In addition, the EPG results indicated that there is no significant difference in the time to first probe, time to reach first sieve element, pathway phase, and non-probing phase among the three sorghum plants, which suggests that the resistance factors present in the vascular tissues of the resistant line (SC265) potentially contribute to the resistance mechanisms against greenbugs. Overall, SC265 NAM parental line showed a combination of antixenotic and antibiotic-mediated resistance mechanisms against greenbugs, whereas the susceptible line Segaolane displayed the least resistance to greenbugs.

Registration of the sorghum nested association mapping (NAM) population in RTx430 background

“…Grover et al. (2019) used the founder lines of the sorghum NAM population to understand sources of sorghum resistance to greenbugs. The study concluded that SC265 showed a combination of antixenotic and antibiotic‐mediated resistance mechanisms against greenbugs, whereas the susceptible line Segaolane displayed the least resistance to greenbugs.…”

“…Likewise, information for reaction to sugarcane aphid [Melanaphis sacchari (Zehnter)] is also available in the GRIN database for a subset of the NAM founders (Table 3). Grover et al (2019) used the founder lines of the sorghum NAM population to understand sources of sorghum resistance to greenbugs. The study concluded that SC265 showed a combination of antixenotic and antibiotic-mediated resistance mechanisms against greenbugs, whereas the susceptible line Segaolane displayed the least resistance to greenbugs.…”

Improving Water Stress Resilient Crop Breeding Using Phenomics and Genomics Information Derived fromSorghum (SorghumbicolorL.)

“…Nested association mapping (NAM) take advantage of both linkage map and association map by combining low marker density and allele richness with high resolution map. There are five NAM population available in sorghum, of which 4 NAM focus on sorghum grain and fifth NAM focus on bioenergy (Boyles et al 2019;Grover et al 2019). In linkage equilibrium, association mapping and NAM, recombination is an important event which occurs in slow rate in linkage mapping and NAM.…”

Dynamic regulation of phenylpropanoid pathway metabolites in modulating sorghum defense against fall armyworm

“…Recently, a nested association mapping (NAM) population for sorghum has been developed by crossing globally diverse lines with a reference line, RTx430, which provides an excellent opportunity to study various valuable agronomic traits (Bouchet et al, 2017). These NAM parental lines have been tested against piercing-sucking insect, greenbugs and sugarcane aphids (Grover et al, 2019;Grover et al, 2020;Grover et al, 2022b), but no information is available on chewing insects. The purpose of this study was to screen NAM parental lines and to dissect the role of phenylpropanoid pathway metabolites in providing resistance/susceptibility to FAW using several different approaches.…”