Ana Pina Sobrino
The problem of graft incompatibility has assumed an important place in the fruit tree industry as the demand for new rootstocks and varieties has increased, this being an important agronomic trait and an essential criteria for selection. However, this incompatibility may be show up after several years of normal plant growth in the field by physiological and morphological alterations that produce the physical breaking of the trees, generating a significant delay in the process of evaluation and transfer of new fruit materials. Hence, it is necessary to know the processes that trigger the graft incompatibility reaction in order to determine this problem at the earliest stages of graft development, potentially affecting the fate of a particular graft combination.
In the last few years, important metabolic pathways have been identified as responsible for physiological failure in graft-incompatible rootstock-scion combinations (phenylpropanoid pathway, cell wall biosynthesis, oxidative stress, etc). In addition, it has been reinforced the hypothesis of the polygenic character and quantitative inheritance of the characters associated with graft compatibility trait. In this context, the main goal of the project is to identify and characterize the genetic mechanisms that regulate the rootstock/scion graft compatibility in order to advance in the development and application of the most suitable genomic and molecular tools to develop molecular markers for marker assisted selection (MAS) in fruit breeding programs, especially in apricot. This goal is divided into three objectives: (1) Analysis of QTLs and candidate genes associated with graft compatibility, (2) study of the phenylpropanoid pathway in graft combinations with know compatibility, (3) determination of graft compatibility from new apricot cultivars grafted on different Prunus rootstocks. The objectives proposed fit within the strategic lines: challenges 8, 6 and 12.
It is a multidisciplinary project which combines the application of genomic tools of new generation sequencing (NGS) directed towards the generation of knowledge for identifying genes and QTLs associated to graft compatibility with the phenotypic evaluation of interesting new apricot varieties grafted on different rootstock using microscopic observations of what goes on inside the graft interface at early stages of development. The origin of the new varieties will be from different breeding programs at national (CEBAS, PSB, IVIA, ALM, Proseplan) and international (INRA-CEP, Escande, ASF, IPS, Cot International) levels and will be facilitated by the EPOs that support the project (nursery of Abel, S.L and nursery Mariano Soria, S.L). The results of this project will provide novel insight into the genetic mechanisms underlying graft incompatibility and will have application into the sector making more dynamic the selection of new fruit plant material. Furthermore, the results will contribute to understand fundamental aspect of graft-(in)-compatibility in fruit trees, targeted marker development and implementation of marker-assisted selection (MAS) into practical breeding programmes in the Prunus spp.
Pilar Errea Abad, Patricia Irisarri Sarto (CITA); Helle Juel Martens (U. Copenague); Dieter Treutter Treutter (U. Munich); Tetyana Nikolaevna Zhebentayayeva (U. Clemson)