Lecture 20 - Hybrids

Question 1

why use hybrids

Answer 1

when the F1 of a cross increased performance over both its parents in commercially important traits

Question 2

hybrids are heterozygous but _________

Answer 2

homogeneous

Question 3

steps to produce hybrids

Answer 3

• develop inbred lines
  -evaluate lines for combining ability
  -determine best parental combination (performance testing)
  -produce hybrid seed

Question 4

methods of pollination control systems in hybrid seed production

Answer 4

-physical emasculation
-self incompatibillity
-gametocides
-nuclear male sterility
-cytoplasmic male sterility

Question 5

male sterility is caused by the ___________

Answer 5

barnase enzyme

Question 6

what is dominant nuclear male sterility linked to

Answer 6

herbicide tolerance gene

Question 7

cytoplasmic male sterility

Answer 7

maternally inherited condition in which a plant is unable to produce pollen but is capable of full seed set when pollinated by a male fertile plant

Question 8

t/f: expression of cytoplasmic male sterility can often be overcome by one or more nuclear restorer genes

Answer 8

t

Question 9

Hybrids use ______ to develop inbreds and then use _____ to pick specific combinations for F1 hybrid production

Answer 9

GCA, SCA