Lesion3 (Les3)
By Jessica Johns &
Erika Bertelsen
Lesion3 (Les3) JLJ, EMB, 1-13-05
Lesion3, what is it?
Lesion3 is a dominant genetic mutation in
which dead spots (lesions) appear on the
leaves of corn plants. The lesions do not
appear on the leaves for about six weeks.
Some lesions
on a leaf from a
Les3 mutant plant
What Causes a Lesion?
A lesion is caused by a genetic mutation.
The basic pattern of DNA is coded with the
nucleotides that are lettered A, T, G, and C.
A is always base-paired with T
G is always base-paired with C
When there is a malfunction or skip in the Les2
gene sequence it causes a mutation. The genetic
mutation then causes a physical mutation which is
expressed as a visible lesion (phenotype) on the
plants leaves.
Our Question
When we first planted our
seedlings we asked ourselves
two questions, how many of
our plants would get lesions,
and just how long our plants
would survive once they
developed lesions. As we
observed our plants over the
weeks we found the answer.
Our Observations
Week 1
Light green stems, small leaves, and no lesions.
Week 2
Bottom leaves are a darker green, while the upper
leaves are still light. The stems are purplish-red, and
there are slight lesions.
Week 3
Plants are now large. No new lesions.
Week 4
Twelve out of the sixteen plants have developed lesions.
The other four are wild-type* in appearance.
* A wild-type is a normal-looking plant which shows no mutation.
Why are there wild types?
Lesion mutant:
Normal:
Ll or LL
ll
Test-cross:
Parents: (P1)
Ll x ll
Offspring: (F1) Ll ll Ll ll
Notice that not all have lesions
Field Pictures of Les3 lesions
Our Answer
Only 12 of our 16 plants showed lesions.
The lesions which developed were not severe,
and we didn’t think they would affect the
plants health.
Our plants which got lesions did not die, but
they did become sick and in time they may
well die.
Reference
1976
RB Ashman & AJ Ullsturp
A Heritable, Noninfectious Necrosis of
Maize Leaves.
Journal of Heredity
Volume 67 Pages 220-222
Field placard
Name: Lesion3 (Les3)
Locus: Chromosome 10
(linkage map bin 10.06)
Field placard by:
Jessica Johns & Erika Bertelsen
Middle School Mentorship, Fall 2004
School of Arts and Sciences
Leon County Charter School
Tallahassee, FL
A special thanks
We would like to offer a special thanks
to…
Dr. Hank Bass
Ms. Debbie Figueroa
Ms. Bobbye Hill
Dr. Brian Ring
And of course our wonderful Ms. Crow
The end