Showing papers by "Daphne R. Goring published in 2003"

ARC1 is an E3 ubiquitin ligase and promotes the ubiquitination of proteins during the rejection of self-incompatible Brassica pollen.

Abstract: ARC1 is a novel U-box protein required in the Brassica pistil for the rejection of self-incompatible pollen; it functions downstream of the S receptor kinase (SRK). Here, we show that ARC1 has E3 ubiquitin ligase activity and contains several motifs that influence its subcellular localization. ARC1 can shuttle between the nucleus, cytosol, and proteasome/COP9 signalosome (CSN) when expressed in tobacco BY-2 suspension-cultured cells. However, ARC1 localization to the proteasome/CSN occurs only in the presence of an active SRK. In the pistil, ubiquitinated protein levels increase specifically with incompatible pollinations, but they do not change in ARC1 antisense-suppressed pistils. In addition, inhibition of the proteasomal proteolytic activity disrupts the self-incompatibility response. We propose that ARC1 promotes the ubiquitination and proteasomal degradation of compatibility factors in the pistil, which in turn leads to pollen rejection.

Increasing plant seed production

Abstract: The invention includes PERK (Proline-rich Extensin-like Receptor Kinase) nucleic acid molecules and polypeptides. A receptor-like protein kinase designated PERK1 (Proline-rich Extensin-like Receptor Kinase 1) was isolated from a (-pistil cDNA library of Brassica napus. The deduced PERK1 protein is comprised of a cytoplasmic domain that contains all of the conserved amino acids prevalent among serine/threonine kinases, a transmembrane domain and an extracellular domain with sequence similarity to the extensin family of plant cell wall proteins. Northern blot analysis demonstrated that PERK1 mRNA accumulated rapidly in leaf and stem tissue of B. napus in response to wounding and treatment with salicylic acid. In contrast, no significant accumulation of PERK1 mRNA was detected following treatment with methyl jasmonate. The rapidity of PERK1 mRNA accumulation in response to these treatments shows a role in plant defense signaling.