University of California, Davis

• BIOLOGY 112

• VI. ROOT DEVELOPMENT //

  D. GENETIC CONTROL OF RAM

  ORGANIZATION

  VII. FLOWER DEVELOPMENT

  A. THE FLOWER

  B. FLORAL ORGAN IDENTITY

  C. EXPRESSION OF FLORAL

  REGULATORY GENES

  ANNOUNCEMENTS

  • Homework #5 due next Tuesday

  • Discussion Section next week – review

  Homework #5 and Study Questions for the

  Final Exam

  • Final Video Presentation Schedule is

  posted – first session on Friday

   

  The Video Assignment

   

  1. Schedules for presentations of The Video Assignment have been distributed.

   

  a. Sessions are scheduled for (1) Friday 5/31 @ 5 pm, (2) Saturday 6/1 @ 2:30 pm, (3)

   

  Sunday 6/2 @ 10:00 am, (4) Monday 6/3 @ 5 pm, (5) Wednesday 6/5 @ 5 pm, and

   

  (6) Sunday 6/9 @ 10 am

   

  b. Each session will last approximately 2.5 hours. All groups are expected to remain in

   

  attendance for the entire session.

   

  2. Each Video will be presented as follows.

   

  a. The Presenter Group’s Video will be shown

   

  b. After the Video is shown, each member of the Presenter Group will introduce

   

  themselves and explain her/his role in creating The Video. The Presenter Group

   

  should also discuss the major points that they are trying to make in the Video.

   

  c. Each member of the Questioner Group will ask questions of the Presenter Group

   

  about The Video. Each person should ask at least two questions. The Questioner

   

  Group will receive a link to the Presenter Group’s Video.

   

  d. Anyone else in the audience may ask questions.

   

  Organization of the Root Apical Meristem

   

  Taiz and Zeiger

   

  endodermis epidermis steele

   

  cortex

   

  Scheres et al. 2003

   

  scarecrow and shortroot Mutations Affect Cortex and Endodermis Cells

Roles of SHORTROOT and SCARECROW in the Root Apical Meristem

1. SHR is transcribed in the stele and pericycle

2. SHR protein is produced in the stele and pericycle

3. SHR protein moves one cell layer into the QC, C/En initial, and endodermis

4. SHR activates the transcription of SCR

5. SHR & SCR are required for the periclinal division of the C/Eni daughter cell and

the specification of endodermal cells

6. SHR & SCR are also required for maintenance of the QC

SCARECROW Gene Expression in shortroot Mutants (pSCR:GFP)

Taiz and Zeiger

From Scheres et al. 2003

Expression of the SHORTROOT Gene

SHR promoter activity

SHORTROOT Protein Moves One Cell Layer and Activates the SCARECROW Gene

Sena G et al. 2004 Lucas & Lee, 2004

* SHR protein moves to these cells

SHR-GFP protein

Question of the Day

What would be the phenotype of a transgenic plant expressing the SHORTROOT gene from the SCARECROW promoter (pSCR:SHR)?