Introduction of Seed Development and

Arabidopsis Embryo Development

By Bekah Charney and Thi NguyenHC70AL Spring 2006

What is the life cycle of an Arabidopsis Plant?2nAdult

Sporophyte

Meiosis

n n n nHaploid spores

Many mitosis

n Adult Gametophyte

Mitosis

n Gametes

2n Zygote

Many Mitosis

2nAdult

Sporophyte

2nAdult

Sporophyte

Meiosis

n n n nHaploid spores

Many mitosis

n Adult Gametophyte

Mitosis

n Gametes

2n Zygote

Many Mitosis

2nAdult

Sporophyte

How do seeds form during the life cycle of a plant?

Double Fertilization of cells leads to seed formation

TORPEDOGLOBULAR HEART MATURATIONEMBRYO

SAC

Embryo Development

Globular Stage

•Stage which precedes cotyledon development

•Embryo proper is spherical

•Note the suspensor

Heart Stage

•Globular embryo develops into two-lobed form

•Suspensor acts as an “umbilical cord,” providing nutrients to the embryo.

Torpedo Stage

•Cotyledons and axis grow longer

•Embryo may remain straight or become curved

Mature Embryo•Cotyledons curve and provides nutrition to plant, enough to get plant started with photosynthesis

•Suspensor disappears

•Endosperm has been used for nutrients and now is used up

Mutations that are Lethal

Lethal to ZygoteLethal to Gamete

Phenotype: live to dead seeds1:1

Genotype: AA to Aa1:1

Phenotype: live to dead seeds3:1

Genotype: AA to Aa1:2

AA

Aa

Aa

aaa

a

A

A

AA

Aa

Aa

aaa

a

A

A

Acknowledgements

• We would like to thank Ria, Jon, XingJun and Tomo for allowing us to use their Nomarski photographs and their assistance in general in helping to make to this presentation

• We would also like to thank Mike, Brandon, Jessica, the rest of the HC70AL class and Dr. Goldberg for being there for us all quarter!