Identification and characterization of a proline-rich mRNA that accumulates during pod development in oilseed rape (Brassica napus L.)

Abstract

Pod development in oilseed rape (Brassica napus) culminates in a process known as dehiscence (shatter) which can result in the loss of seed before the crop is harvested. In order to investigate the biochemical and the genetic basis controlling this process, a cDNA library was constructed from the dehiscence zone of developing pods. This resulted in the isolation of a cDNA clone (SAC51). The mRNA encoded by SAC51 had a transcript size of ca. 700 nucleotides and was found, by northern analysis, to accumulate preferentially in the dehiscence zone of the pod and in no other part of the plant analysed. The predicted polypeptide is rich in the amino acids proline (14.2%) and leucine (14.2%). The sequence of the polypeptide has more than 40% amino acid sequence identity with polypeptides isolated from carrot embryos, maize roots, soybean seeds and young tomato fruit. The function of these proteins is unknown. Genomic Southern analysis suggests that SAC51 is encoded by a single gene or small gene family. The role of the peptide in the development of pods of oilseed rape is discussed.