Root morphology and transcriptome analysis reveal key genes responsive to cadmium in wheat (Triticum aestivum L.)

Cadmium (Cd) is a non-essential metal element for plant growth and development and can be easily absorbed by wheat roots and transported to the grain, thereby posing health risks to human. Therefore, exploring the effects of Cd on wheat root growth and development and key responsive genes are important. In this study, analysis of the root morphology of Aikang58 (AK58) seedlings under 0, 3 and 10 mg/L Cd treatments found that the total root length, total root surface area, and root average volume were significantly decreased while the total root tips were first increased and then decreased as the Cd treatment concentration increased. Subsequently, we analyzed root transcriptome data of AK58 and Chinese Spring (CS) seedlings under 0 and 1 mg/L Cd treatment for 15 days as well as Huixian Hong (HXH) and Xinmai 9 (XM9) at 0, 2, 6, 12, 24, 48, and 72 h post-Cd treatment with 0.2 mg/L, and found 177 key responsive genes. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that these genes were mainly related to amino acid metabolism, ABC transporters, and plant hormone signal transduction. Subsequently, we analyzed the expression of six key responsive genes using AK58 seedlings treated with different Cd concentrations. Interestingly, the expression of TraesCS2B02G394500 in the root showed a significant negative correlation with Cd concentrations. Further analysis of root morphology and ion content in different tissues found that this gene had a significant negative correlation with root development and was verified in five varieties with different genetic relationships with AK58. We found the protein encoded by TraesCS2B02G394500 was YSL12 by bioinformation analysis, which was involved in transmembrane transport of heavy metals. In conclusion, our results lay a theoretical foundation for analyzing the molecular mechanism of wheat in response to Cd.