Picolinate auxin

The final example of our chemical genetic approach to dissect herbicide action involves auxin biology. A subset of our bioactive compound library that exhibited auxinic herbicidal symptoms was tested for inhibition of root growth of Arabidopsis seedlings. The most potent of these compounds was a novel picolinate auxin DAS534. Previous mutational studies with 2,4-D have elucidated an auxin signal- 

AFB3 AFB2 — AFBl TIRl -AFB4 AFB5 

Phylogenetic tree of TIRl auxin receptor gene family in Arahidopsis. 

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Figure 7. A. Mutation sites conferring picolinate auxin resistance in AFB5.

Other auxin-like herbicides (2,48) include the chlorobenzoic acids, eg, dicamba and chloramben, and miscellaneous compounds such as picloram, a substituted picolinic acid, and naptalam (see Table 1). Naptalam is not halogenated and is reported to function as an antiauxin, competitively blocking lAA action (199). TIBA is an antiauxin used in receptor site and other plant growth studies at the molecular level (201). Diclofop-methyl and diclofop are also potent, rapid inhibitors of auxin-stimulated response in monocots (93,94). Diclofop is reported to act as a proton ionophore, dissipating cell membrane potential and perturbing membrane functions. 

Phthalimidopenicillanic acid isocyanate, 532, 534-536 Picoline, 291 Pimelic acid, 506 Pinner reaction, 117,123,124,127 Plant auxin receptor, 84 Plasmin, 206... 

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