#172 leaf chlorosis

Propose to delete duel parentage with abiotic stress trait and leaf color to make term just a child of leaf color
Proposed new definition:
leaf chlorosis - A leaf color trait (TO:0006060) describing the yellowing of leaves, due to insufficient production of chlorophyll.
Comment:
Leaf surface affected by abiotic stresses like insecticides and cold temperature as evidenced by chlorotic tissue.

Proposed to make a new relation called response_to and relate it back to abiotic stress trait