Plant leaf pubescence (hairiness) plays an important biological role in protection against insect and pathogen attack as well increasing tolerance to abiotic stress conditions. In bread wheat leaf hairiness is formed by unicellular trichomes and displays wide phenotypic variation. However, this trait until recently has been methodologically difficult to phenotype. Currently сereal trichome genetic control and developmental mechanisms is poorly understood. We apply systems biology approach to disclosure mechanisms of pubescence formation in wheat.

Using the text mining technology we reconstructed the network of interactions between known leaf pubescence genes using A. thaliana as model organism. This network consists of a several connected fragments responsible for trichome patterning, trichome cell growth and differentiation, and response to stress factors.

Based on the coarse-grained network structure and information about cereal leaf formation a mathematical model of leaf epidermis growth and trichome development was created. The model shows that the reaction-diffusion processes similar to those described A. thaliana epidermis combined with of the cereal epidermal growth process features enough to form the observed trichome spacing pattern in wheat. Also considered the processes of trichome cell growth related to trichome size.

For model parameters verification and comparing them with the quantitative characteristics of leaf pubescence in wheat was performed a large-scale analysis of this trait using previously developed image analysis method (http://wheatdb.org/lhdetect2). We analyzed a leaf hairiness in genetic collection of hexaploid, tetraploid and diploid wheat forms. Distribution of trichome length and density argued for partial independence of genetic control of patterning and growth of trichomes. Several distinct morphological types of leaf pubescence were identified. The diversity in pubescence was observed within these groups also. We demonstrated that the model is suitable for fitting different trichome distribution patterns related to several morphological types of leaf pubescence.

To investigate possible functional role of several genes involved in the control of the leaf pubescence in wheat genetics experiments were performed. This allowed us to describe the role of these genes and interactions between it were in terms of patterning and growth of trichomes.

The analysis shows the effectiveness of the integration of computer and experimental approaches in the study of such traits as leaf pubescence.