Multi-parameter characterization of water stress tolerance in Vitis hybrids for new rootstock selection

How Do Novel M-Rootstock (Vitis Spp.) Genotypes Cope with Drought?

“…M4 and other rootstocks (110R, 161-49C, and SO4) significantly reduced both Gs and Pn values in response to water-stressed conditions ( Figure 1 ). These genotypes are considered “plastic”, due to their ability to modify their performances under different environmental conditions [ 5 , 49 , 50 ]. However, M1 and 140Ru showed an “elastic” behavior, as they maintained unchanged Pn and iWUE levels under both well-watered and water-stressed conditions.…”

“…Unlike other rootstocks, Group C rootstocks (140Ru and 41B) maintained the stomatal conductance under 20% SWC, allowing leaves to continue high photosynthetic activity ( Figure 2 ), regardless of Ψ S ( Figure 3 b). The physiological activity performed at 20% SWC could be related to the adaptation of genotype architecture to drought conditions, such as the vessel size [ 5 , 62 , 63 ]. ( Figure 6 ) However, the expression of genes linked to ABA biosynthesis, especially VvZEP , rose at 50% SWC before decreasing at lower water availability ( Figure 5 a).…”

“…North American Vitis species are able to resist to phylloxera due to having co-evolved with the pathogen, therefore they are utilized as rootstocks, as single or inter-specific hybrids. Rootstocks also contribute to the control of other soil-borne pests such as nematodes, as well as various abiotic constraints, such as drought, salinity, lime-rich soils and deficient mineral nutrition [ 5 , 6 , 7 , 8 ]. They also modify whole plant development, biomass accumulation and phenology [ 9 ].…”

“…Although a significant number of efforts in grapevine rootstock selection have been carried out to date, fewer than 10 rootstocks are widely used in viticulture, with a negative impact on the grapevine response to biotic and abiotic stresses [ 9 , 45 ]. Since 1985, the Department of Agricultural and Environmental Sciences (DiSAA) research group operating at the University of Milan has been working on the selection of new rootstocks able to cope with abiotic stresses [ 5 ]. Some genotypes (series “M”: M1, M2, M3 and M4) were selected and released in 2014 and registered in the National Register of Vine Varieties (RNVV).…”

A Phenotypic Search on Graft Compatibility in Grapevine

“…Although it is believed that the likelihood of graft success is higher when scion and rootstock are closely related or of the same species, graft compatibility between scion and rootstock can vary greatly even between related species and grapevine clones [5]. Inline, predictive and standardized measurements to evaluate compatibility levels would be useful for breeders when considering the use of a rootstock with a specific graft combination [3], particularly in the case of new genotypes under selection with unknown grafting properties [8][9][10]. Indeed, to release a new grapevine rootstock into the market, several traits need to be evaluated including "Phylloxera" and nematode resistance, salt and drought tolerance, and last but not least, graft compatibility with scion species need to be assessed [11].…”