Prolamin storage proteins and alloploidy in wild populations of the small grass Brachypodium distachyon (L.) P. Beauv.

Abstract

This paper reports the glutenin diversity of a collection of 23 wild populations of the grass Brachypodium distachyon collected in the Mediterranean and southern areas of the Iberian Peninsula. The plant material studied included the three different cytotypes of this species: 2n = 10, 2n = 20 and 2n = 30. A specific method of extraction was used to isolate the glutenin subunits from the caryopsis. Separation by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed them to correspond to wheat low-molecular-weight glutenin subunits (LMW-GS). Twenty-two LMW-GS-like were identified that showed great diversity within and between populations. All the populations investigated were polymorphic for the endosperm proteins studied. The 2n = 30 forms had the largest number of subunits; these were also more diverse than those of the 2n = 10 or 2n = 20 forms. The 2n = 10 forms, the most common in the higher, interior areas of the Iberian Peninsula, showed the smallest subunit variation. In fact, negative correlations were found between subunit diversity and altitude and longitude. In contrast, a positive correlation was detected with the annual average temperature and the indices of thermicity and Mediterraneity. The similarity between the populations was estimated using the Sorensen-Dice coefficient, calculated on the basis of the presence/absence of the 22 LMW-GS proteins. The similarity indices were used to produce a dendrogram using the unweighted pair-group method with arithmetic means (UPGMA). This method produced three main groups corresponding to the three cytotypes. An analysis was made of the possible correlation between eco-geographic and climatic factors and the gene diversity and polymorphism shown in the populations. The diversity correlated positively with the number of chromosomes (2n), annual mean temperature, index of thermicity and index of Mediterraneity. In contrast, diversity correlated negatively with altitude, longitude and index of precipitation during the summer. The number of chromosomes correlated negatively with altitude, longitude and precipitation during summer and positively with all the other climatic indices. These results are coherent with the fact that diploid forms were more common in areas of the interior and at higher altitude, where the climate is more extreme.

A comparative study of root system architecture in seedlings ofBrachypodium spp.using three plant growth supports

“…For instance, genotype Bs115 is more related with three genotypes of B. distachyon than the other three genotypes of B. stacei, Moreover, Bd160 and Bh486, appear clearly separated on the dendrogram, probably due to these genotypes have, respectively, the shortest and the largest radicular system of the genotypes of B. distachyon and B. hybridum analysed. These results are similar to those obtained by other authors using biochemical and molecular markers to differentiate between the members of a large collection of genotypes belonging to the present three species of Brachypodium (including those studied in the present work) (Hammami et al 2011(Hammami et al , 2014. The overlap observed in the grouping of the genotypes of the three species can be explained by the existing evolutionary proximity among them, being B. hybridum an allotetraploid of the other two species.…”

“…The plant materials examined included four genotypes each of B. distachyon (2n = 10) (including genotype Bd-21, the full genome of which has been sequenced by the Interna- These genotypes all originated from single plants belonging to 11 wild populations (three of B. dystachyon and four each of B. stacei and B. hybridum), harvested in different places around the Iberian Peninsula (Hammami et al 2011) (Table S1*).…”

Validation of microsatellite markers for cytotype discrimination in the model grass Brachypodium distachyon

“…The allopolyploid origin of B. hybridum is currently out of debate mainly based upon the strong cytogenetic evidences reported by Hasterok and co-workers (Hasterok et al 2004(Hasterok et al , 2006Idziak et al 2011). It has also been confirmed by the analysis of plastid and nuclear gene sequences (Catalán et al 2012) and prolamin storage protein profiles (Hammami et al 2011) on collections of B. distachyon (s.l.) including samples representative of the three cytotypes.…”

Updated taxonomic descriptions, iconography, and habitat preferences of <em>Brachypodium distachyon, B. stacei</em>, and <em>B. hybridum</em> (Poaceae)

“…Phylogenetic analyses of two plastid (ndhF and trnLF) and five nuclear (ITS, ETS, CAL, GI, and DGAT) genes indicated that the more early-diverging B. stacei and the more recently evolved B. distachyon emerged from two independent lineages, confirming their contributions as genome donors to B. hybridum (Catalán & al., , 2014. Further evidence from different molecular sources, like seed protein data (Hammami & al., 2011), nuclear SSRs (Giraldo & al., 2012), DNA barcoding , and isozymes (Jaaska, 2014) have also confirmed the co-occurrence of progenitor B. distachyon and B. stacei markers in the B. hybridum background.…”