MYB transcription factors have been known to have important roles in plant
development, metabolism and stress responses. However, little is known about
their functions in rice.

The rice gene OsMYB103L, which encodes an R2R3-MYB transcription factor, was
examined to determine its function. OsMYB103L was found to be located in the
nucleus. Overexpression of OsMYB103L in rice (Oryza sativa L.) resulted in a
rolled leaf phenotype, an important trait in rice breeding. Further analyses
also found significant increases in expression levels of several cellulose
synthase genes (CESAs), resulting in increased cellulose content in
OsMYB103L overexpressing lines. Silencing of the OsMYB103L gene decreased
the cellulose content and reduced mechanical strength in leaves. Moreover,
expression levels of CESA genes were also decreased in the lines where
OsMYB103L was silenced.

The OsMYB103L appears to target the CESA genes for regulation of cellulose
synthesis and could potentially be manipulated to form desirable leaf shapes
and mechanical strength in rice varieties.

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