Identification of transcripts controlled by ploidy and/or diplosporous apomixis in Eragrostis curvula

JUAN P. SELVA; SILVINA PESSINO; MAURO MEIER; DIEGO ZAPPACOSTA; VIVIANA ECHENIQUE

Simposio; The 6ht International Symposium on the Molecular Breeding of Forage and Turf; 2010

The aim of this work was the identification of genes that are controlled by ploidy and/or by  the  reproductive  mode  in  the  apomictic  grass  Eragrostis  curvula.  An  analysis  of  the  transcriptome was made by differential display of leaves and flowers of a geneticallyrelated  euploid series of  plants  with  different  ploidy levels  and  reproductive  modes.  With  more  than  100  primer  combinations,  4,242  and  7,622  total  markers  were  generated,  rendering  554 and 739 differential bands in flowers and leaves, respectively. From these bands, 11.84  and 6.74% were  related to ploidy  and 0.71 and 2.17%  to the reproductive mode. A small  percentage  of bands (0.5 and  0.78 %) showed similarity between the tetraploid apomictic  and the diploid sexual plants (unexpected pattern). Dendrograms and principal component  analysis graphics showed strong similarity between the tetraploid genotypes suggesting that  ploidy  is  more  important than  tissue  type  in  defining  the  transcriptome  structure. Eighty  seven  sequences  matched  successfully  with  annotated  Arabidopsis  sequences  and  were  assigned to different metabolic pathways. Thirty nine out of 60 and 14 out of 42 sequences  from flowers  and  leaves showed  strong  homology to known genes.  Genes  were  in  silico  mapped  onto  maize  chromosomes,  focused  on  6L,  8L  and  3L  since  the  Tripsacum  dactyloides  DIP  locus  was  shown  to  be  linked  to  csu68  marker,  located  on  them.  Expression of genes located in the diplo-region might be strongly influenced by ploidy and  silenced  in  the  apo  genotype.  These  findings  are  discussed  in  order  to  understand  the  molecular basis of diplospory and its connection with ploidy.