Give one significant contribution of each of the following scientists :
Dmitri Ivanosky

Explanation

**Step-by-Step Solution:**

1. **Identify the Scientist**: The scientist in question is Dmitri Ivanovsky, a Russian microbiologist.

2. **Research His Work**: Dmitri Ivanovsky is known for his research on the mosaic disease of tobacco, which is a significant plant disease.

3. **Understand the Cause of the Disease**: The mosaic disease of tobacco is caused by the tobacco mosaic virus (TMV). This virus is classified as a positive-sense single-stranded RNA virus and belongs to the genus Tobamovirus.

...