Molecular mechanisms, genetic mapping, and genome editing for insect pest resistance in field crops

Abstract

Improving crop resistance against insect pests is crucial for ensuring future food security. Integrating genomics with modern breeding methods holds enormous potential in dissecting the genetic architecture of this complex trait and accelerating crop improvement. Insect resistance in crops has been a major research objective in several crop improvement programs. However, the use of conventional breeding methods to develop high-yielding cultivars with sustainable and durable insect pest resistance has been largely unsuccessful. The use of molecular markers for identification and deployment of insect resistance quantitative trait loci (QTLs) can fastrack traditional breeding methods. Till date, several QTLs for insect pest resistance have been identified in field-grown crops, and a few of them have been cloned by positional cloning approaches. Genome editing technologies, such as CRISPR/Cas9, are paving the way to tailor insect pest resistance loci for designing crops for the future. Here, we provide an overview of diverse defense mechanisms exerted by plants in response to insect pest attack, and review recent advances in genomics research and genetic improvements for insect pest resistance in major field crops. Finally, we discuss the scope for genomic breeding strategies to develop more durable insect pest resistant crops.

Fig. 1

Diverse defense mechanisms employed by plants for insect pest management. The figure illustrates different defense mechanisms imparted by plants, including various direct and indirect defenses, which help them to counteract insect herbivory

Fig. 2

The CRISPR/Cas9-mediated genome editing applications for insect pest resistance in plants. The Cas9-gRNA complex targets desired seuquence in the DNA and produces a double stranded break (DSB) at the 3′ upstream PAM sequence. This results in gene insertion/deletion through non-homogous end joining (NHEJ) mechanism, while gene insertion via homology directed repair (HDR) process. Different genes and receptor genes can be knocked-out to control the insect pest population. gRNA Guide RNA, NHEJ Non-homogous end joining, HDR Homology directed repair, DSB double standard break, pgSIT precision guided sterile insect technique