Composite Cucurbita pepo plants with transgenic roots as a tool to study root development

Area of Science:

• Plant biology
• Root development
• Molecular biology

Background:

• Lateral root primordia typically initiate above the elongation zone in most plants.
• Cucurbits and some other species initiate lateral roots in the apical meristem.
• Composite transgenic plants from Agrobacterium rhizogenes are models for root development studies.

Purpose of the Study:

• To establish Agrobacterium rhizogenes-mediated transformation for squash.
• To create a model system for studying root development in squash.
• To investigate root apical meristem and branching in squash.

Main Methods:

• Cloned auxin-responsive promoter DR5 into binary vectors.
• Used 5-ethynyl-2'-deoxyuridine (EdU) to assess cell proliferation in squash hypocotyls.
• Employed Agrobacterium rhizogenes strains R1000 and MSU440 for transformation.
• Verified construct insertion via PCR and visualized auxin response using fluorescence and GUS staining.

Main Results:

• Six-day-old squash seedlings are suitable for Agrobacterium rhizogenes inoculation.
• Agrobacterium rhizogenes R1000 showed the highest virulence.
• Transformed squash roots did not display the hairy root phenotype and were similar to wild-type roots.

Conclusions:

• The auxin response pattern in squash root apex mirrors that in Arabidopsis.
• Composite squash plants generated through Agrobacterium rhizogenes transformation are effective for studying root apical meristem development and branching.