Hybridity and autopolyploidy increase the expressivity of apospory in diploid Paspalum rufum

DELGADO BENARROCH, LUCIANA; MARIA E. SARTOR; ESPINOZA, FRANCISCO; MARIANO, SOLIMAN; GALDEANO, FLORENCIA; JUAN PABLO A. ORTIZ

PLANT SYSTEMATICS AND EVOLUTION

SPRINGER WIEN

Lugar: Viena; Año: 2016

0378-2697

Paspalumrufum Nees is a perennial grass thatforms amultiploid complex. Natural populations arecomposedmainly of diploid (2n = 2x = 20) and tetraploid(2n = 4x = 40)cytotypes. The diploid form is sexual andhighlyself-sterile, while the tetraploid is pseudogamousaposporousapomict and self-fertile. Diploids can alsodevelopaposporous sacs, and some of them completeapomixis.The objective of this work was to analyseaposporyexpressivity (a gametophytic apomixis component)in diploidhybrids and colchicine-induced autotetraploidsof thespecies. One F1 family was created bycrossingtwo diploid individuals (R6#45 9 R5#49) carryingaposporoussacs in 5.8 and 13 % of their ovules,respectively.Moreover, two synthetic autotetraploids wereobtained bycolchicine treatment of mature seeds fromR6#45. Thehybrid origin of the F1s was confirmed bysegregationanalyses of a morphological trait and molecularmarkers,and the ploidy level of experimental plantswasdetermined by flow cytometry. Apospory expressivitywasestimated by embryo sacs observation at anthesis. Outof the 39hybrids analysed, 38 showed aposporous embryosacs.Expressivity of the trait ranged from 0 to 36 %, andsomeindividuals differed significantly for both progenitors?values.Both doubled-diploid plants showed 25 and32 % of aposporyexpressivity, which was significantlyhigher thanthat observed in R6#45. Results presented inthis workrevealed a high variability in apospory expressivityof diploidhybrids and suggested that more than oneallele arecontrolling the trait. Moreover, the new induceddoubled-diploidplants showed that apospory expressivityis highly ploidy dependent.