Study of the Root System in Four Winter Wheat (triticum aestivum l.) Cultivars Developing Two Contrasting Phenotypes

A development of the root system is a crucial process establishing the whole plant growth and development and directly affects a plant yield. Understanding the development and architecture of roots takes on significance with the climate change, thus an extensive research in this field is needed. In this work, the root system of four wheat (Triticum aestivum L.) cultivars and their growth responses to different water regimes were investigated. When growing in the hydroponic system, the cultivars develop two phenotypes. Group A cultivars (T1, T9) have a smaller total length of roots, however, develop longer individual roots, whereas group B cultivars with a bigger total length of roots (T27, T33) develop shorter individual roots. When growing in soil, two cultivars from the different phenotypic group show contrasting root growth reactions to reduced watering. While reduced watering affects total root dry mass, but not a total length of roots in the A cultivar T9, B cultivar T33 shows opposite reaction. These observations are in agreement with results from hydroponic experiment simulating limited watering using 20% PEG 6000, suggesting similar growth reactions as in soil. For a better understanding of different root morphology development between the A and B cultivars, the RNAseq on total root system was performed. The analysis of differentially expressed genes (DEGs) indicates that the development of the different phenotypes is a process involving auxin (14 DEGs), but probably not cytokinin (2 DEGs). Moreover, the expression of genes involved in the determination of root morphology and anatomy suggests differential regulation of cellulose biosynthesis among the two cultivars contrasting in their root growth reactions under limited watering. To shed light on differential mechanisms involved in the development of roots in the limited watering conditions between the cultivars, histology and carbohydrates content of roots will be investigated.