"The greatest amount of life can be supported by great diversification of structure." Charles Darwin

Saturday, April 19, 2014

Plants manipulated by their worst enemies

Just came across a new paper published in PLOS Biology "Phytoplasma Effector SAP54 Hijacks Plant Reproduction by Degrading MADS-box Proteins and Promotes Insect Colonization in a RAD23-Dependent Manner" by MacLean et al. It is a remarkable story where specialized bacterial obligate parasites phytoplasma deliver effector protein SAP54 that interactswith a number of transcription factors in plants key for floral development. The he abnormal development of floral parts into leafy structures then make the infected plants more attractable to leafhopper vectors helping the obligate phytoplasmas reproduce and propagate. Plants can be manipulated by their worst enemies in such precision and turned into zombie plants!
File:Phyllody on Coneflower with aster yellows.jpg
Echinacea purpurea flowers undergoing phyllody (the scientific term for the abnormal development of floral parts into leafy structures), induced by phytoplasma infection.

Leafhoppers serve as the veihcles for the transmission of phytoplasma parasites
Phloem tissue infected with phytoplasma

This new discovery is reminiscent of crown gall, which is a well-studied disease in plants caused by the bacterium Agrobacterium tumefaciens. Crown galls are tumor-like structures often found at the base of many woody plants. It happens that Agrobacterium is capable of inserting a piece its own gene, known as T-DNA, into the plant genome. The gene products of the T-DNA will then transform the infected cells as a biosynthetic factory to manufacture opines used as a unique source of nitrogen for A. tumefaciens, but not for most other organisms. We as humans have successfully engineered Agrobacterium tumefaciens and its T-DNA to make any kind of transgenic plants nowadays.
Crown gall on an spindle tree