Complementation of the Pina (Null) Allele with the
Wild Type Pina Sequence Restores a Soft Phenotype in Transgenic Wheat. (W-wanjugi530638-oral)
Authors:
H. Wanjugi* - Montana State Unv.
M.J. Giroux - Montana State Unv.
J.M. Martin - Montana State Unv.
A. Blechl - ARS Crop Improvement and Utilization Research Unit
Abstract:
Wheat (Triticum aestivum L.) grain hardness is a major determinant of milling and wheat end- product quality. The trait is controlled by the Hardness (Ha) locus located on the short arm of chromosome 5D (5DS). This locus contains the
puroindoline A (pina) and the puroindoline B (pinb) genes. Hard textured wheats contain a mutant pinb allele or are devoid of pina (null) (pina-D1b), while soft wheats carry the pina-D1a and pinb-D1a alleles. Our objective was to determine the effect of complementing the pina-D1b allele in hard wheat cultivar ‘Bobwhite’
(pina-D1b/pinb-D1a) by expression of the pina-D1a sequence in transformed wheat plants. Immature embryos from cultivar ‘Bobwhite’ were bombarded with a DNA construct containing the pina-D1a sequence under control of the wheat glutenin regulatory sequences to obtain ‘BWA’ lines with added pinA. Southern blot and PCR screening confirmed the presence of the pina-D1a transgene in six
independent transgenic lines. Northern blot and triton X-114 protein extraction confirmed the stable expression of the transgene at the RNA and protein level.
Grain kernel hardness was determined on transformed plants. High expression of wild type PINA in transgenic wheat seeds resulted in seeds having a soft chalky appearance and greatly decreased kernel hardness. These findings indicate that the absence of pina in hard wheats carrying the pina-D1b allele is causative to a hard phenotype. Further, pina expression and presence influences friabilin association with starch therefore regulating grain texture phenotype.
Speaker Information: Humphrey Wanjugi, Montana State Unv., Montana State Univ.
Department of Plant Pathology, Bozeman, MT 59717-3150; Phone: 406 994 3952;
E-mail: [email protected]
