Xylem anatomy and hydraulic traits in Vitis grafted cuttings in view of their impact on the young grapevine decline

Abstract

Grapevine grafting is an essential practice in viticulture and over the years, various bench grafting techniques have been developed to mechanize the nursery process and to increase the yield in number of viable cuttings. Bench grafting is a fundamental nursery practice that can potentially affect the quality of propagation material also in young decline associated to grapevine trunk diseases and has been recently reported to influence leaf symptoms development associated with diseases of Esca complex. The study aimed to investigate how three bench grafting methods [i.e., (i) Omega graft as mechanical technique, (ii) Whip and Tongue graft as manual technique and (iii) Full Cleft graft as semi-mechanical technique] can influence these phenomena. Specifically, the different methods were compared for their effect on the anatomical development of the grafting point and the functionality of the xylem, also considering two factors: the grapevine cultivar (Cabernet Sauvignon, Glera and Teroldego) and the scion/rootstock diameter (thin and large). Observations by light microscopy on the anatomical evolution and measurements on the xylem morphology and hydraulic traits were correlated with the grafting methods and the investigated varieties. The anatomical observations revealed that the mechanical (Omega) and semi-mechanical (Full Cleft) grafting methods have a faster callusing response while the manual technique (Whip and Tongue) has a slower but greater vascularization of the differentiated callus. Significant differences between cultivars and/or grafting types were also detected in necrotic area on the grafted tissues. Statistical analysis of the grapevine vessels suggested differences in xylem parameters between cultivars, while grafting type had no significant effects. On the other hand, the grafting type significantly affected the intrinsic growth rate. The study confirms the potential incidence of lesions and dysfunctionalities correlated with the grafting method applied, which can potentially induce grafted vine declines in vineyards due to the necrotic area detected on the grafted tissues.

Grapevine histological responses to pruning: the influence of basal buds on tissue defence reactions

“…In V. vinifera, a species with creeping habit, pruning wounds do not heal as in fruit trees, where the stem cambium usually develops new tissues such as callose (Nakashima et al, 2003;Câmpu, 2009;Grünwald et al, 2002;Battiston et al, 2022). Neither does the plant produce suberin in comparison to other trees (Rittinger et al, 1987;Hawkins and Boudet, 1996) to protect the internal living tissues against the external environment.…”

“…Samplings were carried out either on the same day as pruning (experimental control, T0); or aft er 1 (T1), 2 (T2), or 9 (T9) months aft er pruning. Th ree replicates from different plants (biologically independent) were examined at each sampling time (n = 3), following the methods described by Battiston et al (2022). For each of the four pruning methods (described above), at T0 and T1 the percentages of stem vessels occluded by tyloses were recorded, at T2, light microscopy observations of histological responses were carried out, and at T9, the desiccation areas below the wounds were described.…”

Secondary metabolites in grapevine: crosstalk of transcriptional, metabolic and hormonal signals controlling stress defence responses in berries and vegetative organs

“…In addition, in small vessel-cultivars, the ease of occluding the vasculature could favour the physical compartmentalization of fungi ( Pouzoulet et al., 2014 ; Pouzoulet et al., 2020a ). A recent study showed that in the nursery, three different grafting techniques adopted on three different V. vinifera varieties onto the same rootstock (Kober 5BB) allowed diverse levels of callus formation and vascularization of the grafting point ( Battiston et al., 2022 ). Such results confirm the influence of the genotype on wood formation and response to pathogens.…”