Expansins are proteins that can loosen the cell wall. Previous studies have
indicated that expansin-encoding genes are also involved in defense against
abiotic stresses. However, little is known about their involvement in the
defense against biotic stresses. The team of Jiang Tan from the Chinese
Academy of Sciences found that one rice (Oryza sativa) expansin-encoding
gene, OsEXPA10, functions in both plant growth and biotic resistance.

Overexpression of OsEXPA10 in rice improved plant growth. However, it also
increased susceptibility to brown planthopper (BPH), a major insect pest of
rice, infestation and to rice blast caused by Magnaporthe grisea. On the
other hand, knock-down of the gene resulted in reduced plant height and
grain size, but with increased resistance to BPH and rice blast.

These results imply that OsEXPA10 mediates the balance between rice
development and biotic resistance. This could serve as foundation for future
studies on the development of improved rice varieties.



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