Maize Genomics and Genetics 2025, Vol.16, No.6, 316-324 http://cropscipublisher.com/index.php/mgg 318 the plants become shorter. Although the overall trend is that plant height and panicle height decrease simultaneously under heat stress, ASI is elongated, and the growth rhythm is disrupted, it cannot be generalized (Turc et al., 2016; Hosamani et al., 2020; Bista et al., 2022). This complexity also reminds us that we cannot judge the heat tolerance level merely by the height of the plant. Some materials with medium plant types actually show a good ability to develop filaments. 3.2 Anthesis-silking interval (ASI) as an indicator of heat tolerance When it comes to heat resistance or not, many people's first reaction is to look at ASI. Indeed, on hot days, the filaments often come out later than the pollen, and the ASI suddenly elongates. This "asynchronization" is the key factor leading to failed pollination and reduced yields. However, there are exceptions. Some materials can maintain a relatively short ASI even at high temperatures, thus ensuring the success rate of fertilization. Compared with other phenotypes, ASI appears more intuitive and easier to measure. Especially now that the automated platform can monitor the flowering period and silk production in real time, the breeding work has become much more efficient than before (Figure 1) (Zhuang et al., 2024). However, short ASI does not mean everything is good. It is necessary to consider factors such as the activity of the filaments and the pollination environment together. Figure 1 Partial images of the dataset created (Adopted from Zhuang et al., 2024) 3.3 Agronomic management (planting density, irrigation) modulating silk emergence under stress Breeding is of course important, but sometimes, management methods can also be a "rescue". Before the arrival of high temperatures, it is not new but often overlooked to appropriately reduce the density, avoid planting too densely, and keep up with the watering. In fact, when the density is relatively high, the competition among plants intensifies, and the already fragile filaments become even more strained for development. Water is equally crucial. Once the soil moisture level fails to keep up, the "dual pressure" of high temperature and drought will significantly delay silk spinning. In addition, strategies such as adjusting the sowing period to avoid the peak of high temperatures and choosing hybrid varieties that are more suitable for the local climate are also quite practical at the farmer level. These practices, in combination with genetic resistance, are often more reliable than going it alone (Borras and Vitantono-Mazzini, 2018; Dong et al., 2021). 4 Application of Multi-Omics Approaches in Fine Mapping of QTLs Under Heat Stress 4.1 Integrative genomic and transcriptomic analysis for candidate region identification Relying solely on a single omics approach to locate QTLS, especially under the multi-factor interference of high-temperature stress, is often hard to convince people. Nowadays, an increasing number of studies tend to combine genomic and transcriptomic data, especially when looking for candidate genes related to filaments. This joint strategy is not new, but it does improve the accuracy of positioning. Once information such as GWAS, linkage maps, and transcriptome expression is integrated, many key genes and QTL regions can emerge relatively clearly, especially when dealing with flowering regulation and stress response (Longmei et al., 2021). However, differential expression alone is not enough; some regulatory sites only function in specific circumstances. At this point, the eQTL map can make up for the deficiency. It can further refine the localization of the regulatory region, especially being very helpful when dealing with changes in expression patterns at high temperatures. 4.2 Construction of co-expression networks linking gene expression and phenotypes Not all genes with upregulated expression are important; the key lies in identifying those that act in unison. This is
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