Lecture 9- Plant mating systems and reproductive strategies

Question 1

2 main types of plant reproductive system

Answer 1

outbreeding systems
selfing systems e.g. apomixis and autogamy

Question 2

conditions which may lead to outbreeding

Answer 2

inbreeding depression- want to avoid this
optimal allocation of reproductive structures for the environment

Question 3

conditions which may lead to selfing

Answer 3

difficulties with reproductive assurance

Question 4

dichogamy

Answer 4

separation of sex organs in time, e.g. maturing of M organs before F (protoandry) or vice versa

Question 5

herkogamy

Answer 5

separation of sex organs in space, so it becomes nearly impossible to self- e.g. style length polymorphism

Question 6

dicliny

Answer 6

sexual dimorphism, with different sexes spread through a population- can have different combinations of single sex and cosexual

Question 7

what is self-incompatibility

Answer 7

plants being able to reject their own pollen

Question 8

how are life history and mating type related

Answer 8

selfers tend to be annual, outcrossers tend to be perennial (less risk of not reproducing?)

Question 9

correlations between ecology and mating system

Answer 9

where there is more diversity in pollinators, crossing is more likely, whereas if pollinators are sparse, there may be more selfing

Question 10

most effective pollination principle

Answer 10

plants should specialise on the most abundant or effective pollinator, if it is reliably present

Question 11

gametophytic self incpmatibility

Answer 11

incompatibility is defined by the haploid genome of a single organism- co-dominant S alleles at the pistil, vs a single allele at the pollen which can decide compatibility

Question 12

when does inhibition happen in GSI

Answer 12

post-pollen tube formation, before reaching the ovule

Question 13

sphorophytic self incompatibility

Answer 13

incompatibility phenotype of the pollen is determined by the diploid genome of the parent plant rather than the pollen grain itself- more room for dominance to interfere, can still get compatibility even with 2 of the same allele present if it isn’t dominant

Question 14

normal number of S alleles

Answer 14

about 20-40, but can be significantly more or fewer

Question 15

traditional model of self incompatibility

Answer 15

production of slightly different ligands and receptors, allows self recognition

Question 16

example in mustards (Brassicaceae)

Answer 16

in an SSI system- female determinant SRK encodes a receptor at the stigma surface, male determinate encodes a ligand in the pollen coating that can bind with SRK and cause signalling which eventually inhibits incompatible growth

Question 17

example of a non-self recognition system

Answer 17

RNase systems (GSI)- secretion of female RNase, males produce a ubiquitin kinase which binds to this RNase and targets it for breakdown, preventing RNA breakdown

Question 18

correlation of GSI/SSI and type of recognition system

Answer 18

not important