Which of the following statements is/are correct?

Viruses can infect

1. bacteria
2. fungi
3. plants

Select the correct answer using the code given below:

The correct answer is 1, 2 and 3 — Viruses can infect bacteria, fungi, as well as plants. All three statements are correct.

To understand why, let us explore each statement in detail:

Statement 1: Viruses can infect Bacteria
This is absolutely correct. Viruses that specifically infect bacteria are called Bacteriophages (or simply "phages"). They are among the most well-studied viruses in biology. A bacteriophage attaches to the surface of a bacterial cell, injects its genetic material (DNA or RNA) into the host bacterium, and hijacks the bacterial machinery to replicate itself. Eventually, the bacterial cell lyses (bursts open), releasing hundreds of new phage particles. The T4 bacteriophage infecting Escherichia coli is a classic textbook example. This discovery was fundamental to the development of molecular biology.

Statement 2: Viruses can infect Fungi
This is also correct, though less commonly known. Viruses that infect fungi are called Mycoviruses (from the Greek word "mykes" meaning fungus). These viruses are widespread in the fungal kingdom and have been found in all major groups of fungi, including Ascomycetes, Basidiomycetes, and Zygomycetes. A well-known example is the virus found in Agaricus bisporus (the common mushroom), which causes "La France disease" in cultivated mushrooms, leading to severe economic losses. Mycoviruses generally have double-stranded RNA genomes and are transmitted through spores and hyphal anastomosis (fusion). Their existence demonstrates that viruses can parasitize even organisms from the kingdom Fungi.

Statement 3: Viruses can infect Plants
This is also entirely correct. Plant viruses are a significant cause of agricultural diseases worldwide and result in enormous crop losses every year. Unlike animal viruses, plant viruses cannot penetrate the rigid cell wall of plant cells on their own; they typically enter through wounds, insect vectors (like aphids and whiteflies), or mechanical damage. Once inside, they spread from cell to cell through plasmodesmata (tiny channels connecting plant cells). Famous examples include:

- Tobacco Mosaic Virus (TMV): Historically the first virus ever discovered; it infects tobacco and many other plants, causing a characteristic mosaic-pattern discoloration on leaves.
- Tomato Yellow Leaf Curl Virus (TYLCV): Transmitted by whiteflies, causes severe damage to tomato crops.
- Rice Tungro Virus: A major constraint on rice production in South and Southeast Asia.

Summary of Why All Three Are Correct:
Viruses are the most abundant biological entities on Earth and are remarkably non-discriminatory in terms of their hosts. They have evolved to infect organisms across all domains of life:

- Bacteria → Infected by Bacteriophages
- Fungi → Infected by Mycoviruses
- Plants → Infected by Plant Viruses (e.g., TMV)

This universality of viral infection is a testament to how viruses have co-evolved with virtually every form of cellular life. Therefore, all three statements — 1, 2, and 3 — are correct, making "1, 2 and 3" the right choice.