max1

Max1, often written as MAX1, stands for More Axillary Branches 1 in plant genetics. It is a gene found in Arabidopsis thaliana and other flowering plants that belongs to the MAX gene family, which regulates shoot branching by controlling the biosynthesis and signaling of strigolactones, a class of plant hormones.

Functionally, MAX1 encodes a cytochrome P450 monooxygenase that participates in strigolactone biosynthesis. It catalyzes oxidation steps in which carlactone is converted to carlactonoic acid, a key intermediate that leads to the production of active strigolactones which suppress the growth of axillary shoots.

Genetic studies show that loss-of-function max1 mutants exhibit increased branching, consistent with a role in limiting shoot proliferation. MAX1 operates within the strigolactone pathway alongside MAX3 and MAX4, which generate carlactone, and MAX2, a component of the downstream signaling pathway. Expression of MAX1 is influenced by developmental cues and environmental factors such as nutrient status.

Orthologs of MAX1 are widespread in flowering plants, and related genes influence plant architecture and tillering in crops. In various species, MAX1-like cytochrome P450 enzymes shape strigolactone profiles that affect interactions with soil microbes and, in some cases, parasitic plants. Understanding MAX1 and related genes informs breeding and biotechnological approaches aimed at optimizing plant height, branching patterns, and resource-use efficiency.