Field Crop 2025, Vol.8, No.1, 41-50 http://cropscipublisher.com/index.php/fc 43 assemble transcripts, and finally using DESeq2 to analyze differential expression. However, in actual operation, each step may encounter some minor problems. After analyzing the differentially expressed genes, you still have to figure out what these genes do. The GO and KEGG pathway analysis used by Li et al. (2021) is good and can help us understand the biological functions of these genes. Interestingly, through co-expression network analysis, we found that the interaction between lncRNAs and mRNAs is quite complex, which is very helpful for understanding drought resistance mechanisms. But to be honest, although these analysis tools are powerful, sometimes the results are still a bit difficult to interpret. 3.3 Challenges in transcriptome profiling for drought stress studies Although technology has advanced a lot in the study of drought-responsive genes, there are still many headaches. Liu et al. (2022) found that different rapeseed varieties and different growth stages responded to drought very differently. Just doing a time series experiment requires an awful lot of data, which makes analysis very difficult. What's more complicated is that transcriptome data alone may not be enough. Boldura et al. (2015) pointed out earlier that metabolome data should be combined to get a more comprehensive view. But the problem is that after finding the key genes, functional verification must be done, which is a time-consuming and expensive step. And to be honest, some genes do not perform exactly the same under different experimental conditions, which is even more troublesome. 4 Identification of Drought-Responsive Genes in Rapeseed 4.1 Key drought-responsive genes and their functional roles In the study of drought resistance mechanisms in rapeseed, several key genes have been identified. The BnaC08g41070 gene, located near an important association site, showed correlation with drought response (Tan et al., 2017). Notably, members of the trehalose-6-phosphate synthase gene family (BnTPS6, BnTPS8, BnTPS9, and BnTPS11) were significantly upregulated under drought stress, suggesting their potential role in carbon allocation and drought resistance (Figure 1) (Yang et al., 2023). In addition, BnNRT2.1a and BnNRT2.5 in the NRT2 gene family were found to be associated with nitrate metabolism under drought conditions, but their specific regulatory mechanisms still need to be further elucidated. These findings provide important clues for understanding the molecular mechanisms of rapeseed drought resistance, although the synergistic network between genes remains to be resolved. 4.2 Transcriptomic signatures of drought stress in rapeseed When rapeseed encounters drought, the changes in gene expression are quite amazing. Research by Tan et al. (2019; 2020) showed that the drought-tolerant variety Q2 and the sensitive variety Qinyou8 behaved very differently under drought conditions. In Q2, 5 546 genes were downregulated and 6 997 were upregulated, while the changes in Qinyou8 were more dramatic-7 824 were downregulated and 10 251 were upregulated. Behind these numbers, there is a complex regulatory network. Transcription factors and lncRNAs seem to play an important role in this. However, it is interesting that the difference between the two varieties is so large, indicating that drought resistance may involve multiple levels of gene regulation. Which specific pathways are the most critical may require more in-depth analysis. 4.3 Functional categories of drought-responsive genes Different genes perform different functions when rapeseed responds to drought. Xue et al. (2022) divided these genes into several categories according to their functions. For example, some genes are specifically responsible for transmitting signals, such as those near BnaC07g44670D, which are mainly responsible for plant hormone signal transduction. Interestingly, genes that produce proline and ubiquitin ligase E3 are particularly active in drought resistance. Tong et al. (2020) found that the NRT2 gene family is also very important and is specifically responsible for the transport of nutrients. As for the TPS genes, the trehalose they produce can not only regulate carbon distribution, but also directly improve drought resistance. However, how these genes work together may require more research.
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