Imagine you have a garden with lots of plants growing in it. Just like how you get sick and need medicine to help you feel better, plants can also get sick from things like bacteria and viruses. But some plants are better at fighting off these sicknesses than others - kind of like how some kids have really strong immune systems that make them less likely to get sick.
Scientists have been working for a long time to figure out why some plants are better at fighting off sicknesses than others. They've found that some plants have something called "resistance" - which means they have special parts of their cells that can recognize when a sickness is trying to attack them, and fight it off before it can cause too much damage. It's like when you see someone coming to give you a high five but you know their hands are dirty, so you put your arm up to block them and don't get their germs on you.
Farmers and gardeners really like plants with resistance, because it means they don't have to use as many chemicals or medicines to keep the plants healthy. So, scientists are trying to figure out how we can make more plants have this resistance - maybe by finding the parts of the plants that are really good at fighting off sicknesses, and somehow getting them into other plants. That way, more plants can stay healthy and happy for longer!