Characterisation of mRNA transcripts differentially expressed in apomictic flowers of Paspalum notatum

PESSINO, SILVINA C.; ESPINOZA, FRANCISCO; ORTIZ, JUAN P. A.; MARTÍNEZ, ERIC J.; VALLE, ESTELA M.; QUARIN, CAMILO L.

Victoria, Australia

Congreso; Second International Symposium Molecular Breeding of Forage Crops 2000; 2000

In apomictic PaspaJum notatum apomeiosis accounts for the abortion of all four megaspores produced by female meiosis and the aposporous development of embryo sacs from nucellar cells. The embryo develops by parthenogenesis and the endosperm by pseudogamy. Sexual plants produce exclusively meiotic sacs and the seed is generated by double fertilisation. We compared the mRNA fingerprints produced by spikelets from either sexual or apomictic plants of an F1 progeny segregating for reproductive mode. Total RNA was extracted two days before anthesis and equally bulked into apomictic and sexual pools. mRNA composition was compared by differential display (Liang and Pardee 1992). Several cDNA fragments were identified, isolated and cloned. Sequencing of three independently isolated clones, which showed enhanced expression in apomicts, revealed that they all belonged to a unique family of transcripts showing highly significant homology. Anchored PCR followed by Southern analysis of each individual plant revealed an expression level around 30 times higher in apomictic than in sexual individuals. Fragments are currenlly being used in genomic studies of the F, progeny to determine whether they co-segregate with apomixis.