I have tomato seedlings that the leaves have started turning a whitish colour, they are also pale green in colour. They are about 3″ to 5″ tall. They are Money Maker, Alicante, Ailsa Craig and tumbling tom. I grew them from packet seed,as I do every year with very good results. There is about 300 plants. I usually supply family and friends and a local shop takes the surplus. I am not a comercial grower, I just cannot give plants to anybody in case it is a virus etc.
This is not virus or other disease.
Tomato plants will usually grow out of this damage if the growing point is intact, which it usually is. Try to avoid a repeat of the damage.