Selection of New Grape Varieties and Clones Flashcards
Ampelographic platform
identify and propagate only the best vines
Productive hybrids
breeding for resistance
Main goals for grapevine breeding
resistance to fungi, pest, virus, nematodes, bacteria; resistance to freezing, frost, drought; fruit quality; regular productivity; improve tolerance to BSN, chlorosis…; other agronomic issues
Role of breeding
increase variability in populations; selection of new genotypes with improved adaptability; rediscover, protect and create biodiversity; provide new material allowing adaptation to market evolution
Grapevine breeding methods (traditional)
mass selection; clonal selection; intraspecific crossbreeds; interspecific crossbreeds
grapevine breeding methods (innovative)
assisted selection (cell and tissue ‘in vitro’ culture); protoplast fusion; somaclonal variation; gene transfer (transgenesis and cisgenesis)
Intra-varietal variability
the presence of many genotypes within a grapevine variety; within a population of a given cultivar a certain number of individuals with different genetic makeup as compared to the true type can be identified.
Causes of genetic variability
Polyclonal origin of grapevine varieties; long term accumulation of genetic mutations
Somatic mutations
a main source of diversity within a grapevine variety (in a given bud, mutations affect genetic makeup of meristem cells)
Source of somatic variation
viruses, ionizing radiation, thermal shock or mechanical trauma; physical and chemical mutagens
Factors influencing levels of intravarietal variability
time span (during which grape variety was developed); spatial diffusion… the longer the variety has been cultivated, and more diffusion over different regions it experiences, will grow the intravarietal variability
Ancient origin
varieties grown over long period of time
Recent origin
varieties more recently planted
Mass selection
identification of grapevines (by empiric method: direct or indirect observation) from which collect scions for propagation
Scion
a young shoot or twig of plant
Positive mass selection
identification of grapevines showing positive traits concerning growth and productivity; tagged vines will be the only one where buds will be collected
Negative mass selection
identification of grapevines showing negative traits concerning growth and productivity; they will be tagged and excluded during bud sampling process
Clonal selection aims to…
identify; verify; check health status; propagate
Selective pressure (high)
clones with high adaptability to different environment and wine styles; combination of several positive characters in a single individual not easy to achieve; because positive and negative characters are frequently associated, many individuals are excluded; as a cause of genetic erosion, dramatically reduces the intravarietal variability of genotypes subjected to clonal selection
Check the health status (clonal selection aims)
of mother-plant-derived material before propagation
Identify (clonal selection aims)
healthy grapevines showing improved agronomical and/or enological traits as compared to average of variety
Timeline for new clone
at least 13 years, in general 15 years are required to obtain a new clone
Selective pressure (low)
aims to preserve morphological and functional variability of varieties subjected to clonal selection; protection of minor traits are difficult to determine (anthocyanin and aroma profiles); reduces interaction between genotype and environment (higher stability in different environments over years)
Clonal selection
“Population of vines all derived by vegetative propagation from cutings or buds from a single mother-vine by deliberate clonal selection”; only recognized way to obtain clones
