He is an expert in phytopathology, making a significant contribution to agriculture.

He is a specialist in that field.

He is an expert in pathology.

He is majoring in botany at university.

He owns a big house.

I am doing volunteer work to contribute to the community.

His research made a significant contribution to the scientific community.

My father is engaged in agriculture.

He is an expert in pathology.

His specialty is physics.