Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2007
Publication Date: 3/1/2008
Citation: Xia, L., Geng, H., Chen, X., He, Z., Lillemo, M., Morris, C.F. 2008. Silencing of puroindoline a alters the kernel texture in transgenic bread wheat. Journal of Cereal Science 47:331-338. Interpretive Summary: Grain hardness is an important determinant of end-use quality and a major factor affecting trade of bread wheat today. Grain hardness is controlled by the hardness locus (Ha), located on the short arm of chromosome 5D. Presently, 11 single nucleotide mutations in Pinb and four Pina mutations have been reported in bread wheat, which result in a kernel hardness change from soft to hard. A wide sequence variability of Pina and Pinb has also been found in wild diploid relatives of wheat, but all the new alleles described in Aegilops tauschii confer soft endosperm when expressed in synthetic hexaploid wheat. In this study, an over-expression strategy was employed and PINA knock-out lines were obtained. Analysis of these lines provides information on further understanding of the formation of kernel texture and the potential for modifying grain texture through genetic engineering in cereal plants.
Technical Abstract: Grain hardness is an important end-use quality parameter of bread wheat, and one of the most important characters for quality improvement. The objective of this study was to further understand the function of puroindolines and the underlying mechanism in the formation of kernel texture. The highly efficient expression vector pUBPa harboring puroindoline a (Pina) was introduced into the bread wheat cultivar Zhongyou 9507-60 via biolistic transformation and transgenic plants were obtained. The integration of the foreign Pina gene was confirmed by PCR and genomic DNA Southern blot analysis. The levels of friabilin on the surface of water-washed starch granules varied among the transgenic lines. SDS-PAGE analysis of Triton X-114 extracted protein showed that the PINA protein was absent in three transgenic lines, indicating that the endogenous Pina gene most likely had been co-suppressed by the over-expression of the Pina transgene. SKCS kernel hardness and scanning electron microscopy analysis further confirmed the changes of kernel texture in these lines.