State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China.
United States Department of Agriculture, Fargo, ND 58102-2765, USA.
Int J Mol Sci. 2023 Jan 21;24(3):2138. doi: 10.3390/ijms24032138.
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 regarding DIMBOA content. In this study, the best linear unbiased prediction (BLUP) values of DIMBOA content in two ecological environments across 310 maize inbred lines were calculated; and their phenotypic data and BLUP values were used for marker-trait association analysis. We identified nine SSRs that were significantly associated with DIMBOA content, which explained 4.30-20.04% of the phenotypic variation. 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, 6 involved in sugar metabolism/homeostasis, 2 regulating peroxidases activity, 21 associated with growth and development [(auxin-upregulated RNAs (SAUR) family member and v-myb avian myeloblastosis viral oncogene homolog (MYB)], and 7 involved in several key enzyme activities (lipoxygenase, cysteine protease, restriction endonuclease, and ubiquitin-conjugating enzyme). The synergy and antagonism interactions among these genes formed the complex defense 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 3 highly (DIMBOA content was 402.74-528.88 μg g FW) and 15 moderate (DIMBOA content was 312.92-426.56 μg g FW) insect-resistant genotypes were major enriched in the Reid group. These insect-resistant inbred lines can be used as parents in maize breeding programs to develop new varieties.
玉米幼苗含有大量的 2,4-二羟基-7-甲氧基-1,4-苯并恶嗪-3-酮（DIMBOA），其作用与抗亚洲玉米螟和玉米叶蝉等多种害虫的多种昆虫抗性直接相关。尽管已经确定了多个具有多种昆虫抗性性状的遗传位点，但关于 DIMBOA 含量的遗传控制却知之甚少。本研究在两个生态环境中，对 310 个玉米自交系的 DIMBOA 含量的最佳线性无偏预测（BLUP）值进行了计算，并对其表型数据和 BLUP 值进行了标记-性状关联分析。我们鉴定出 9 个与 DIMBOA 含量显著相关的 SSR，这些 SSR 解释了 4.30-20.04%的表型变异。结合先前研究中的 47 个原始遗传位点，我们检测到 19 个热点基因座和大约 11 个热点基因座（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 和 Bin 10.04 区），它们支持与两个或多个昆虫抗性性状相关的多效性。在这 19 个热点基因座中，我们鉴定出 49 个候选基因，包括 12 个控制 DIMBOA 生物合成的基因、6 个参与糖代谢/稳态的基因、2 个调节过氧化物酶活性的基因、21 个与生长和发育相关的基因[（生长素上调 RNA（SAUR）家族成员和 v-myb 禽髓细胞瘤病毒癌基因同源物（MYB）]和 7 个参与几个关键酶活性（脂氧合酶、半胱氨酸蛋白酶、限制性内切酶和泛素连接酶）的基因。这些基因之间的协同和拮抗相互作用形成了多种害虫诱导的复杂防御机制。此外，在所测试的 310 个玉米自交系中，报告了 DIMBOA 表现和 SSR 标记的充足遗传变异，3 个高度（DIMBOA 含量为 402.74-528.88 μg g FW）和 15 个中度（DIMBOA 含量为 312.92-426.56 μg g FW）抗虫基因型主要富集在 Reid 组中。这些抗虫自交系可作为玉米育种计划的亲本，用于开发新品种。
