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Wilting evaluation revealed that DED resistance are good heritable attribute. Earlier work about Netherlands, Spain and you can Italy have obtained DED unwilling elm genotypes of the crossing U. slight with Far-eastern elms (Solla ainsi que al., 2005a ; Santini et al., 2008 ). The current efficiency exhibited this new heritability from DED opposition contained in this You. slight. The latest heritability on the effectiveness wilting illness various other kinds is backed by multiple decimal genetic degree, age.g. regarding Fusarium xylarioides–Coffea myladyboydate canephora otherwise Ceratocystis fimbriata–Eucalyptus solutions (Rosado ainsi que al., 2010 ; Musoli et al., 2013 ). Since tree reproduction courses expect one genetic increases is collective more than generations, an additive genetic perception guarantees the overall performance regarding possibilities, and you can strengthens the ability to generate a bank away from genetic resources out-of You. lesser resistant to DED preserving new genetic integrity of your local varieties.

The newest The wordpress platform of your own Roentgen ? R (GR-DF3 ? AB-AL1) and you may R ? S (J-CA2 ? TO-AL1) crossings that were at random chose getting intricate anatomical and you will mental findings was indeed comparable (Dining table 2). Yet not, its notably lower WordPress versus checked out S ? S progeny (CR-PB1 ? TO-PB1) allows a real discussion on the candidate characteristics involved in DED opposition systems.

The current results argue against the hypothesis of a direct link between resistance to drought-induced cavitation and resistance to DED in U. minor. The shape and slope of the VCs, as well as P_fifty and P₈₀, did not differ significantly among DED resistance groups (Table 3; Fig. 1). Therefore, although cavitation is involved in the DED syndrome (Newbanks et al., 1983 ), the current results suggest that xylem resistance to water-stress cavitation is not related to U. minor resistance to DED. The low values of P₅₀ found for the species (c. ?1 MPa) should be noted, which is in agreement with the behaviour of other riparian trees (Tyree et al., 1994b ; Cai & Tyree, 2010 ).

₅₀. For instance, among-species P₅₀ variation has already been explained by differences in mean vessel diameter (VD) or pit membrane surface area (A_pit) (Wheeler et al., 2005 ). Cai & Tyree ( 2010 ) further discussed this P₅₀–VD relationship and found an exponential relationship within Populus tremuloides when considering vessel diameter size classes. The current results did not show any relationship between VD and P₅₀ in U. minor, although vessel size classes as described in Cai & Tyree ( 2010 ) have not been investigated. Vessel size differences between groups (Table 3; Fig. 2) indicate that vessel size is a key factor in determining xylem vulnerability to DED infection in U. minor, in agreement with previous research (Solla et al., 2005b ), but there is no evidence of its involvement in resistance to water-stress-induced cavitation.

Furthermore, unwilling elms put in the pure communities normally transfer its resistance to DED on local gene pool due to intimate breeding

Trees that were more susceptible to DED (i.e. progeny of the S ? S cross) had longer and wider vessels (VD, VL_maximum and bVL; Table 3, Fig. 2). Previous studies have reported that larger conduit size contributes to a faster upward movement of the pathogen and pathogen-produced toxins as a result of greater sap flow (Solla & Gil, 2002 ; Solla et al., 2005b ; ). In the current study, the theoretical hydraulic conductance (THC; Table 3) was higher for progeny of the S ? S cross, but there were no significant differences in Kx_max, CLVF, CMVF and CSVF between groups (Table 3). Therefore, although vessel length and diameter are involved in DED resistance, it is still not clear if it is due to their effect on conductivity.