Invasive sorghum aphid: A decade of research on deciphering plant resistance mechanisms and novel approaches in breeding for sorghum resistance to aphids

During the last decade, the sorghum aphid (Melanaphis sorghi), previously identified as sugarcane aphid (Melanaphis sacchari), became a serious pest of sorghum, spreading to all sorghum-producing regions in the United States, Mexico, and South America, where crop losses of 50%-100% have been reported. Developing sorghum cultivars with resistance to this insect is the most sustainable strategy for long-term pest management. To design cultivars with aphid resistance, comprehensively understanding the mechanisms underlying aphid survival, host plant resistance, and aphid-sorghum interactions is critical. In this review, we summarize the comprehensive efforts to characterize the aphid populations as well as their interaction with sorghum plants via hormonal pathways that trigger various genes including leucine rich repeats, WRKY transcription factors, lipoxygenases, calmodulins, and others. We discuss efforts made during the last decade to identify specific genomic regions and candidate genes that confer aphid resistance, as well as describe recent successes and potential challenges in breeding for aphid resistance. Furthermore, we discuss the use of disruptive technologies like high-throughput phenotyping, artificial intelligence, or machine learning for developing aphid resistant sorghum cultivars. Integration of these new technologies has the potential to accelerate the development and design of novel traits that confer durable aphid resistance in new sorghum cultivars to defend sorghum against new aphid genotype development. Understanding aphid-sorghum interactions, mechanisms underlying aphid survival, and plant tolerance is crucial for sorghum breeding. Efforts are made during the last decade to address sorghum-aphid problems to identify key genes for enhancing resistance to sorghum aphids. High-throughput technologies coupled with genome-based breeding, genome editing, and artificial intelligence enable accelerated development of aphid-resistant varieties.