Crossbreeds, Hybrids, Rootstocks

Question 1

Genetic Improvement by Sexual Reproduction

Answer 1

commonly used for obtaining new varieties; selection of individuals from combination of two gametes, male and female; self-pollination, intraspecific hybrid (crossbreed), interspecific hybrid

Question 2

Crossbreed

Answer 2

sexual union of two individuals belonging to same species; selection of varieties obtained by crossing; knowledge of characters (monogenic vs. polygenic traits); degree of transmissibility (not well known)

Question 3

Self-pollination (classification)

Answer 3

A x A

Question 4

F1) Simple Combination (classification)

Answer 4

A x B ; Ervi = Barbera x Croatina)

Question 5

F2) Backcrossing (classification)

Answer 5

(A x B) x A ; Carla = Cardinal (Flame Tokay x Alfonso Lavallée) x A. Lavallée

Question 6

Convergence (classification)

Answer 6

(A x B) x (C x D) ; Matilde = Italia (Bicane x M. d’Amburgo) x Cardinal (Fl. Tokay x A. Lavallée)

Question 7

Homozygous trait

Answer 7

the 2 alleles of given gene are identical

Question 8

Heterozygous trait

Answer 8

the 2 alleles of given gene are different

Question 9

Dominant allele

Answer 9

expressed in both homozygous and heterozygous individuals

Question 10

Recessive allele

Answer 10

expressed just in homozygous individuals

Question 11

Self-pollination

Answer 11

increases homozygosity and consequently recessive traits can easily appear

Question 12

Inbreeding

Answer 12

reduces grapevine vigor in terms of vegetative growth, bud fruitfulness and yield

Question 13

Selection Criteria

Answer 13

plant habit and productivity; phenology (blooming, veraison)

Question 14

Interspecific hybrids

Answer 14

combination of two individuals from different Vitis Spp. aiming to: introduce biotic resistance traits in Vitis vinifera varieties (productive hybrids); backcrossing with V. vinifera to gain superior wine quality; improve abiotic resistance of grapevine rootstocks; improve biotic resistance of grapevine rootstocks

Question 15

Abiotic resistance

Answer 15

active lime, drought, freezing

Question 16

Biotic resistance

Answer 16

phylloxera, nematodes, bacteria

Question 17

Origin of Grapevine Rootstocks

Answer 17

1868- Phylloxera is discovered in France; 1869- first grafting on Partenocissus quinquefolia; 1876- first planting of productive hybrids; 1877- first hybrids Vitis spp. X V. vinifera. Ganzin 1 (Aromaon x V. rupestris) showed very low resistance to phylloxera (beginning of rootstock breeding)

Question 18

Aims of Rootstock breeding

Answer 18

resistance to phylloxera; resistance to nematodes; tolerance to water stress and mineral deficiency; adaptability to high levels of active lime in soil; vigor control