Researchers from the Hebrew University of Jerusalem have discovered a two-step mechanism in which auxin first suppresses gibberellin to enable organ formation, and later increases it to promote leaf expansion.
To form a compound leaf, the plant must perform two tasks in the correct order: first determine where the leaves will formLeaves, and then allow them to expand. Research fromThe Hebrew University Reveals how two plant hormones Coordinate the transition between stages.
The research was led by Dr. Alon Israeli and Prof. Naomi Uri from the Faculty of Agriculture, Food and Environment, and was conducted in plants. TomatoThe researchers focused on the interrelationships between Auxin and gibberellin, a hormone that encourages growth and expansion of tissues.
At the beginning of leaf development, auxin activates genes that break down gibberellin and represses genes involved in its production. The local decrease in gibberellin levels leaves the young tissue in a state where new leaves can still be initiated.
Later, the direction of control changes. Auxin encourages the production of gibberellin, which pushes the cells to grow and expand the leaf stalk. Thus, the same hormone – auxin – exerts opposite effects on the gibberellin pathway at different times.
The researchers combined genetic engineering, hormonal treatments, and gene expression analysis. When gibberellin activity was too high early on, fewer leaflets formed. When its level was low, more leaflets formed, but prolonged deficiency impaired the proper expansion of the leaf.
The study explains how the plant separates the timing of structural planning from its growth. In the long term, understanding the mechanism may help develop crops with optimized leaf structure, but the research does not yet present a new crop variety or a proven increase in yield.
Questions and Answers
What is the role of auxin in the mechanism?
It first suppresses gibberellin, and later encourages its activity.
Why is a low level of gibberellin necessary at the beginning of leaf development?
To allow the young tissue to continue to create new leaves.
Is less gibberellin always beneficial?
No. A low level may allow for the formation of additional leaves, but later gibberellin is required for proper growth and expansion.
More of the topic in Hayadan:
- Research reveals what allows plants to create an infinite variety of shapes
- Researchers have deciphered the movement mechanism of the hormone gibberellin
- How is the final size of the organs determined?
- Auxin and the self-repair mechanism of plant roots
For the scientific article: [Article in the journal Development]
