Cytogenetics and characterization of microsatellite loci for a South American pioneer tree species, Croton floribundus

Abstract

Despite the recent advances in plant population genetic studies, the lack of information regarding pedigree, ploidy level, or mode of inheritance for many polyploids can compromise the analysis of the molecular data produced. The aim of this study was to examine both microsatellite and cytogenetic characteristics of the pioneer tree Croton floribundus Spreng. (Euphorbiaceae) to test for the occurrence of polyploidy in the species and to evaluate its implications for the appropriate use of SSR markers. Seven microsatellite markers were developed and screened for 62 individuals from a semi-deciduous tropical forest in Brazil. Chromosome number, meiotic behavior, and pollen viability were evaluated from male flower buds. All SSR loci were highly polymorphic. The number of bivalents observed in meiosis n = 56 (2n = 8× = 112) and the maximum number of alleles per individual (Ni = 8) demonstrated the occurrence of polyploidy in C. floribundus. The normal meiotic pairing and the high pollen viability suggested that C. floribundus is a regular and stable polyploid, most likely an allopolyploid. The combined SSR and cytogenetic data provided new evidence on the origin and evolution of the species as well as assured the accurate use of SSR loci for population genetic studies of the polyploid pioneer species.

Transferability of microsatellite loci from Croton floribundus Spreng. to Croton urucurana Baill. (Euphorbiaceae)

“…Unlike the extract reported in C. floribundus (Silvestrini et al, 2013) and what is expected for pioneer species (Coley, 1993), the DNA extracts obtained in the present study needed to be purified with ammonium acetate for secondary compounds. Concerning literature, there is greater difficulty in obtaining intact DNA sampling from tropical species, due to the presence of secondary compounds, especially of the phenol class (Rath et al, 1998; Deshmukh et al, 2007).…”

“…The precipitate was washed with 70% ethanol and diluted in 40 μl of TE buffer (10 mM Tris-HCl, pH 8.0; 1 mM EDTA). Source: Silvestrini et al (2013).…”

“…Transferability was tested with SSR primers designed and developed for C. floribundus species (Silvestrini et al, 2013), totaling 7 pairs of primers (Table 1). The protocol used by Silvestrini et al, (2013) for primers amplification in C. floribundus was the following: final volume 25 μl, 40 ng DNA, 1x reaction buffer, 0.1 mmol.L -1 dNTP, 2 mmol.L -1 MgCl2, 10 pmol of each primer (forward and reverse) and 1.0 U of Taq DNA Polymerase; with thermocycler programmed with 5 min at 95°C as initial denaturation, followed by 30 amplification cycles (denaturation at 95°C for 1 min, annealing at 55°C for 1 min, extension at 72°C for 1 min), ending with a 5 min elongation at 72°C.…”

Variation in the population structure between a natural and a human‐modified forest for a pioneer tropical tree species not restricted to large gaps

“…It is a polyploid (Silvestrini et al. ), shade‐intolerant, fast‐growing tree species commonly found in the gaps of primary forest remnants, as well as in secondary areas of the semi‐deciduous tropical forest (Lorenzi ; Gandolfi et al. ; Rodrigues ).…”

“…1) is recognized as a pioneer species by Rodrigues (1995) and Gandolfi et al (1995). It is a polyploid (Silvestrini et al 2013), shade-intolerant, fast-growing tree species commonly found in the gaps of primary forest remnants, as well as in secondary areas of the semi-deciduous tropical forest (Lorenzi 1992;Gandolfi et al 1995;Rodrigues 2005). The species range includes other forests in Brazil and in Eastern Paraguay (Lorenzi 1992;Gandolfi et al 1995;Rodrigues 2005;Gomes 2006).…”