Genetic variation, DIMBOA accumulation, and candidate genes identification in maize multiple insect-resistance

Authors: ZHAO, XIAOQIANG - Gansu Agricultural Uiversity; NIU, YINING - Gansu Agricultural Uiversity; Chao, Wun; LU, PEINA - Gansu Agricultural Uiversity; BAI, XIAODONG - Gansu Agricultural Uiversity; MAO, TAOTAO - Gansu Agricultural Uiversity

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2023
Publication Date: 1/23/2023
Citation: Zhao, X., Niu, Y., Chao, W.S., Lu, P., Bai, X., Mao, T. 2023. Genetic variation, DIMBOA accumulation, and candidate genes identification in maize multiple insect-resistance. International Journal of Molecular Sciences. 24. Article 2138. https://doi.org/10.3390/ijms24032138.
DOI: https://doi.org/10.3390/ijms24032138

Interpretive Summary: Maize seedlings contain high amounts of DIMBOA, a powerful antibiotic. DIMBOA is directly associated with multiple insect-resistance and functions as natural defense against insect pests such as Asian corn borer and corn leaf aphids. In this study, we investigated the regulation of genes regarding DIMBOA content since this information is required to develop new varieties with enhanced insect-resistance. Using a genetics approach, we identified 49 candidate genes at 19 hotspots on maize chromosomes via a maize population of 310 inbred lines. The numerous genes within these regions could be potential resources for improving insect-resistance. In addition, we also identified several highly and moderate insect-resistant inbred lines, and they can be used as parents in maize breeding programs to develop new varieties.

Technical Abstract: Maize seedlings contain high amounts of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), and the effect of DIMBOA is directly associated with multiple insect-resistance against insect pests such as Asian corn borer and corn leaf aphids. Although numerous genetic loci for multiple insect-resistant traits have been identified, little is known about genetic controls re-garding DIMBOA content. In this study, we identified nine SSRs that were significantly associated with DIMBOA content and the best linear unbiased prediction (BLUP) values of DIMBOA content in two ecological environments across 310 maize inbred lines via a general linear model (GLM) and mixed linear model (MLM), which explained 4.30–20.04% of the phenotypic variance. Combined with 47 original genetic loci from previous studies, we detected 19 hot loci, and approximately 11 hot loci (in Bin 1.04, Bin 2.00-2.01, Bin 2.03-2.04, Bin 4.00-4.03, Bin 5.03, Bin 5.05-5.07, Bin 8.01-8.03, Bin 8.04-8.05, Bin 8.06, Bin 9.01, and Bin 10.04 regions) supported pleiotropy for their association with two or more insect-resistant traits. Within the 19 hot loci, we identified 49 candidate genes including 12 controlling DIMBOA biosynthesis, six involving in sugar metabolism/homeostasis, two regulating peroxidases activity, 21 associated with growth and development (aux-in-responsive SAUR family member and MYB), and seven involving several key enzyme activi-ties (lipoxygenase, cysteine protease, restriction endonuclease, and ubiquitin-conjugating en-zyme). The synergy and antagonism interactions among these genes formed the complex de-fense mechanisms induced by multiple insect pests. Moreover, sufficient genetic variation was reported for DIMBOA performance and SSR markers in the 310 tested maize inbred lines, and three highly and 15 moderate insect-resistant genotypes were identified in Reid group. These insect-resistant inbred lines can be used as parents in maize breeding programs to develop new varieties.