Screening of Different Actinidia Germplasm Resources in Relation to the Tolerance of Kiwifruit Vine Decline Syndrome

Kiwifruit Vine Decline Syndrome (KVDS) is a sever disease, which causes dramatic yield losses and economic damage in Actinidia deliciosa and A. chinensis orchards. Currently, the aetiology is considers an interaction of both biotic and abiotic factors, primary soil-borne pathogens, and waterlogging conditions. Up to date, there is not any effective managing strategy. Nevertheless, the availability of a large Actinidia germplasm collection open up to the possibility of screening different species in order to find traits to contrast KVDS. In this context, we selected six accessions of Actinidia (A. macrosperma 176 and 183, A. arguta cv. Miss Green, A. Polygama, cv. ‘Bounty71’ and A. deliciosa cv. Hayward as control), planted in four KVDS inducing soils. Evaluation of the genotypes behaviour one year from planting was carried out on the root system, considering different agronomic parameters, along with the vegetative plant growth. Yet, a statistical method was developed to define Actinidia root system fitness. Furthermore, the capability of mineral up taking, and protein content was evaluated in roots. The concentration of mineral elements was measured by using the Inductively Coupled Plasma-Atomic Emission Spectrometry, whilst the total protein content was measured through the Bradford assay. Indeed, discontinuous sodium dodecyl-sulfate polyacrylamide gel electrophoresis was performed in order to determine protein patterns. The results showed that significant differences exist among the genotypes, regarding both the radical systems parameters and vegetative growth. Moreover, there was a different content of mineral elements and proteins, without differences on protein’s patterns. These first evidence demonstrated how some accessions were able to grow in KVDS inducing soils, showing a different behaviour for each analysis performed; in particular the best performing was A. macrosperma Only A. polygama was not able to grow, showing a progressive decline trend similar to Actinidia deliciosa cv. Hayward.