The kiwifruit sensibility to Pseudomonas syringae pv. Actinidiae (Psa) is worldwide well known, as well as the damages on the plants that compromise their survival and the productivity. Some cultivars have been demonstrated to be so sensitive that in some area all the plants died. We are presenting a breeding program where we induce mutagenesis on seeds, pollen and in vitro growing calli in order to obtain genotypes tolerant or resistant to Psa. In the first year, Ethyl methanesulfonate (EMS), at three different concentrations (0.2, 0.3, 0.4%), was used on seeds belonging to different Actinidia species. A total number of 3540 'Hayward' open pollinated (o.p.) seeds (A. Deliciosa), 3300 seeds of a CRA-FRU selection named RII 28 (A. chinensis) and 3240 seeds of another A. chinensis selection named C8, kindly obtained from the Udine University were mutagenized respectively. More than 90% of the seeds germinated and, after 60 days, all the seedlings were inoculated with a Psa suspension of the CRA-FRU 8.43 (1-2×106 ufc/ml) race with a direct injection in the leaf. Symptoms were detected every week after the inoculum. After three months the survived plants were inoculated again. One hundred and thirty-seven 'Hayward' o.p. plants, 65 of RII 28 and 24 of C8 plants survived after the second inoculation, respectively. In spring, only five plants of 'Hayward' o.p. treated with 0.2% EMS were still alive. In the second experimental year, EMS was directly used on pollen. Anthers were left for 1 or 2 h in a 1% EMS solution and then the treated pollen was used in different crossings. 13000 seeds were collected and planted in December 2012. A very low germination rate (9%) was observed. The plantlets were inoculated, from the end of May to the end of June, with a leaf vein injection and the smallest ones with irrigation with a bacterial water suspension (1×106 ufc/ml). All the 24 survived plants were analyzed by PCR to establish the presence/absence of the bacteria. In December 2013, the third year, about 2400 seeds of each of the two A. Deliciosa selections (RXII 75 and RXVI 131) and the A. chinensis selection RII 28 were mutagenized with EMS at a concentration (1%). To induce mutagenesis, EMS was also applied to in vitro growing calli obtained from leaves of A. chinensis, 'Soreli' and A. Deliciosa, 'Hayward'.
