Exploring the Transcriptional Responses of Wheat to Sowing Density and Cultivar Mixtures

Cultivar mixtures enhance diversity in fields, offering multiple agronomic benefits while remaining compatible with mechanized agriculture. However, mechanization introduces limitations, such as sowing density, which can influence crop yield. In order to assess the impact of agricultural practices on the plant physiological state, targeted gene expression analysis provides a useful approach. The molecular responses of crops to sowing density and varietal mixtures, particularly in wheat, remain poorly explored. In this study, we examined the transcriptional responses of two binary mixtures of wheat cultivars grown at two sowing densities over two years in semi-controlled mesocosm conditions, using RT-qPCR. Despite notable year-to-year variation in gene expression, consistent transcriptional trends were identified. Sowing density significantly influenced gene expression, particularly in pathways related to carbon metabolism, with cultivar-specific effects. Interactions between sowing density and cultivar mixtures were also observed, with different gene expression patterns across wheat cultivars. While the direct influence of cultivar mixtures on gene expression was limited, three specific genes-particularly in durum wheat-were differentially regulated under mixture conditions. These findings indicate that external environmental factors play a dominant role in shaping gene expression, but the molecular effects of sowing density and varietal diversity should be further considered to optimize sustainable agricultural practices.