Efficacy of Tissue Culture in Virus Elimination from Caprifig and Female Fig Varieties (Ficus carica L.)

Fig mosaic disease (FMD) is a viral disease that spreads in all Tunisian fig (Ficus carica L.) orchards. RT-PCR technique was applied to leaf samples of 29 fig accessions of 15 fig varieties from the fig germplasm collection of High Agronomic Institute (I.S.A) of Chatt-Mariem, to detect viruses associated to FMD. Analysis results show that 65.5% of the accessions (19/29) and 80.0% (12/15) of the fig varieties are infected by FMD-associated viruses. From all fig accessions, 41.4% of them are with single infection (one virus) and 24.1% are with multi-infections (2 virus and more). Viruses infecting fig leaf samples are Fig mosaic virus (FMV) (20.7%), Fig milde-mottle-associated virus (FMMaV) (17.25%), Fig fleck associated virus (FFkaV) (3.45%), and Fig cryptic virus (FCV) (55.17%). A reliable protocol for FCV and FMMaV elimination from 4 local fig varieties Zidi (ZDI), Soltani (SNI), Bither Abiadh (BA), and Assafri (ASF) via in vitro culture of 3 meristem sizes was established and optimized. With this protocol, global sanitation rates of 79.46%, 65.55%, 68.75%, and 70.83% respectively for ZDI, SNI, BA, and ASF are achieved. For all sanitized varieties, the effectiveness of meristem culture for the elimination of FCV and FMMaV viruses was related to meristem size. Meristem size 0.5 mm provides the highest sanitation rates ranging from 70% to 90%

Prevalence of Viruses Infecting Autochthonous Grapevines in Tunisia

The incidence of virus infections was conducted in the grapevine germplasm collection at the Institut National de la Recherche Agronomique de Tunisie. In this grapevine collection, 162 different autochthonous cultivars were maintained, including numerous spontaneous ecotypes coming from different Tunisian grapevine growing regions. All accessions were sampled and analyzed by DASELISA for the presence of Grapevine leafroll associated viruses 1, 2, 3 (GLRaV-1, -2, -3), Grapevine fanleaf virus (GFLV), Grapevine fleck virus (GFkV) and Arabis mosaic virus (ArMV), using commercial polyclonal antisera. Almost all the major grapevine-infecting viruses assayed, except for ArMV, were detected in the tested cultivars. Conversely, all the wild grapevine accessions were found to be free from the same viruses. Out of 141 cultivars submitted to DAS-ELISA, 40.4% were infected with at least one virus. GLRaV-3 was the prevailing virus (23.4%), followed by GLRaV-1 (19.6%), GFkV (9.2%), GLRaV-2 (4.2%), and GFLV (1.4%). Cultivars collected from northern regions (61.4%) were more infected than their homologues from southern regions (19.7%)

Sanitary Selection of Virus-Tested Fig (Ficus carica) Cultivars in Tunisia

Field surveys were carried out during autumn 2011 and spring 2012, in different fig orchards located at Rafraf, Takelsa, Mornag, Djebba, Sousse, and Sfax to select virus-free plants. A total of 202 trees representing 26 fig cultivars were prospected and sampled. Total nucleic acids were extracted from leaf veins and tested by RT-PCR for the presence of FMV,FLMaV-1, FLMaV-2, FMMaV, FCV, and FFkaV using specific primers. PCR results indicate that all these viruses were present in the Tunisian fig orchards. The average of infection level determined by RT-PCR was 63.86%. FMV was proved to be the most widespread virus (37.12%), followed by FLMaV-1 (11.9%), FFkaV (11.4%), FCV (8.9%), FMMaV (8.4%), and finally FLMaV-2 (5.9%). Among the 26 tested cultivars, only 7 (Marghrebi, Boukhobza, Zagfar, Assafri, Kahli, Chetoui, Delgane) were free from the tested viruses. By the contrary, the sanitary status of the main Tunisian cultivars Bayoudhi, Bouhouli, Soltani, Zidi and Bither, seemed heavily degraded (75, 70.37, 69.23, 66.03, and 46.15% of infection, respectively). Seven cultivars (Wahchi, Khartoumi, Thguegli, Besbessi, Bidh-Bghal, Njeli and Khedhri) were totally infected. This study allowed the identification of at least one “virus-tested” candidate clone from 19 different fig cultivars which can represent the potential mother plants for propagating materials in order to establish new fig nurseries and orchards