Plant Science

Staying Low to the Ground

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Science  10 Sep 2010:
Vol. 329, Issue 5997, pp. 1261
DOI: 10.1126/science.329.5997.1261-c

Too much transferase leads to highly branched shoots.

CREDIT: TOGNETTI ET AL., PLANT CELL 22, 10.1105/TPC.109.071316 (2010)

As summer temperatures peak, air conditioning keeps indoor plants from wilting, but those outside need other strategies to cope with the heat. Hormone systems forge a link between environmental stresses and physiological responses. IBA (indole-3-butyric acid), a naturally occurring variant of the plant hormone auxin, accounts for about a quarter of the free auxin in Arabidopsis seedlings. Auxins have a variety of effects, including modulating the pattern of root and shoot development. How much hormone is made and where it is located are regulated by biosynthesis, degradation, transport, and metabolic interconversion.

Tognetti et al. have identified a glucosyl transferase in Arabidopsis that adds a glucose to IBA preferentially. This transferase is induced in response to increases in reactive oxygen species, which are produced by environmental stress, and overexpressing it altered normal flowering time, leaf shape, apical dominance, and chlorophyll accumulation. Plants with excess transferase were unusually tolerant of drought and high salinity, and the expression pattern in younger tissues suggests that this enzyme may be part of a signaling pathway that alters plant shape in response to environmental stress.

Plant Cell 22, 10.1105/tpc.109. 071316 (2010).

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