Pyramids of QTLs enhance host–plant resistance and Bt-mediated resistance to leaf-chewing insects in soybean

Abstract

Key messageQTL-M and QTL-E enhance soybean resistance to insects. Pyramiding these QTLs withcry1Ac increases protection against Bt-tolerant pests, presenting an opportunity to effectively deploy Bt with host–plant resistance genes.AbstractPlant resistance to leaf-chewing insects minimizes the need for insecticide applications, reducing crop production costs and pesticide concerns. In soybean [Glycine max (L.) Merr.], resistance to a broad range of leaf-chewing insects is found in PI 229358 and PI 227687. PI 229358’s resistance is conferred by three quantitative trait loci (QTLs): M, G, and H. PI 227687’s resistance is conferred by QTL-E. The letters indicate the soybean Linkage groups (LGs) on which the QTLs are located. This study aimed to determine if pyramiding PI 229358 and PI 227687 QTLs would enhance soybean resistance to leaf-chewing insects, and if pyramiding these QTLs with Bt (cry1Ac) enhances resistance against Bt-tolerant pests. The near-isogenic lines (NILs): BenningME, BenningMGHE, and BenningME+cry1Ac were developed. BenningME and BenningMGHE were evaluated in detached-leaf and greenhouse assays with soybean looper [SBL, Chrysodeixis includens (Walker)], corn earworm [CEW, Helicoverpa zea (Boddie)], fall armyworm [FAW, Spodoptera frugiperda (J.E. Smith)], and velvetbean caterpillar [VBC, Anticarsia gemmatalis (Hübner)]; and in field-cage assays with SBL. BenningME+cry1Ac was tested in detached-leaf assays against SBL, VBC, and Southern armyworm [SAW, Spodoptera eridania (Cramer)]. In the detached-leaf assay, BenningME showed the strongest antibiosis against CEW, FAW, and VBC. In field-cage conditions, BenningME and BenningMGHE suffered 61 % less defoliation than Benning. BenningME+cry1Ac was more resistant than BenningME and Benningcry1Ac against SBL and SAW. Agriculturally relevant levels of resistance in soybean can be achieved with just two loci, QTL-M and QTL-E. ME+cry1Ac could present an opportunity to protect the durability of Bt genes in elite soybean cultivars. These results should assist the development of effective pest management strategies, and sustainable deployment of Bt genes in soybean.

Pyramiding of Alleles from Multiple Sources Increases the Resistance of Soybean to Highly Virulent Soybean Cyst Nematode Isolates

“…& Gerd.) (quantitative), and leaf-chewing insects (quantitative) (Dorrance et al, 2008;Shi et al, 2009;Li et al, 2010;Ajayi-Oyetunde et al, 2016;Ortega et al, 2016).…”

“…Rotation to nonhost crops such as corn (Zea mays L.) can be a means of SCN control; however, this method does not completely eradicate the pathogen from the soil due to SCN's ability to overwinter in soil for several years (Porter et al, 2001;Jackson et al, 2005;Miller et al, 2006). Nematicide seed treatments have recently been made available to producers, but they need to be combined with genetic resistance to protect yields (Tylka et al, 2015;Tenuta and Tenuta, 2015).…”

Distinguishing Proof and Utilization of Resistance of Insect Pests in Grain Legumes: Progress and Limitations

“…In soybean, wild relative PI 171444 (MG VI) was found to be the majorly resistant and exhibited antixenosis, antibiosis, and temporal separation (Kester et al 1984), and the lines PI 229358, PI 227687, and PI 274454 expressed antixenosistype resistance against Anticarsia gemmatalis (Hubner) (Lepidoptera: Noctuidae) (Hoffmann-Campo et Ortega et al 2016) PI 227687 also provoked repellency to Trichoplusia ni caterpillars and adults of Epilachna varivestis, verified for the presence of volatile derivatives of their leaves (Liu et al 1989). PI 567336A and PI 567598B were confirmed as the most resistant wild relatives and were characterized as having antibiosis resistance to kudzu bug (KZB), Megacopta punctatissima Montandon (Bray et al 2016).…”

“…V. nakashimae has been used to develop an interspecific linkage map with V. umbellata (Somta et al 2006). QTL-M and QTL-E enhance soybean resistance to major insects; pyramiding these QTLs with cry1Ac increases protection against Bt-tolerant pests, presenting an opportunity to effectively deploy Bt with host plant resistance genes (Ortega et al 2016).…”

Registration of Two Soybean Germplasm Lines Containing Leaf‐Chewing Insect Resistance QTLs from PI 229358 and PI 227687 Introgressed into ‘Benning’

“…GP‐406, PI 679959; QTL‐M, QTL‐G, QTL‐H, and QTL‐E) are highly resistant to CEW, SBL, VBC, and fall armyworm [FAW, Spodoptera frugiperda (J.E. Smith)] (Ortega et al, 2016). Pyramiding two insect resistance loci (i.e., QTL‐M and QTL‐E) is feasible in a breeding program.…”