2023-10-13 22:50:45
Plants have developed efficient antiviral mechanisms to protect their stem cells, according to molecular biologists from the Austrian Academy of Sciences (ÖAW). In a recent study published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), the researchers described the molecular path that plants use to keep their stem cells virus-free.
Stem cells play a crucial role in the life of multicellular organisms, including mammals and plants. They are essential for regeneration and ensure the transmission of life to the next generation through germline cells. The GMI – Gregor Mendel Institute for Molecular Plant Biology of the Austrian Academy of Sciences discovered how plants exclude viruses from their stem cells.
The study, led by Marco Incarbone, a former postdoctoral researcher at GMI and now a group leader at the Max Planck Institute for Molecular Plant Physiology in Potsdam, focused on the molecular basis of virus defense in plant stem cells. Stem cells are found at the top of the plant and are responsible for creating above-ground plant tissue and ovules for the next generation. Interestingly, viruses cannot multiply in these stem cells.
To understand the antiviral defenses of stem cells, the researchers set up a screening platform using high-throughput microscopy techniques. They observed that viruses initially penetrate the stem cells but are quickly expelled. “Surprisingly, these cells are really good at expelling the virus,” said Incarbone.
The researchers followed clues from previous work on RNA interference and salicylic acid to understand the mechanisms behind this defense. RNA interference inhibits the replication of viruses in both plants and animals, while salicylic acid plays a role in plant virus defense. By using Arabidopsis mutants and plants lacking salicylic acid, the team discovered that salicylic acid is produced during a viral infection and activates RDR1, a key factor for enhancing RNA interference. RDR1 increases the production of virus-specific sequences, directing the defense mechanism against the invading virus.
The researchers found that both salicylic acid and RDR1 are necessary to expel the Turnip Mosaic Virus from stem cells. However, different viruses may trigger slightly different defense signaling pathways. Despite the variations, the study concluded that RNA interference is always necessary to protect stem cells from infection.
The study provides important insights into the defense mechanisms of plant stem cells and opens up further questions for investigation. One question that remains unanswered is why viruses can bypass RNA interference in most parts of the plant but not in the stem cells. Future studies will also aim to understand how viruses are prevented from penetrating seeds and infecting the offspring of an infected plant.]
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