First cytomolecular characterization of three Neotropical woody bamboos (Bambusoideae, Poaceae) suggests ancient diploidized karyotypes

Julia Zappelini,Rosete Pescador,Luiz Gustavo Souza,Miguel Pedro Guerra

doi:10.1590/0102-33062019abb0261

Julia Zappelini, Rosete Pescador + Show 2 more

Open Access

https://doi.org/10.1590/0102-33062019abb0261

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Abstract

ABSTRACT Although karyotype features are useful data for evolutionary studies, cytogenetic data in Bambusoideae are mainly based only on chromosome counts. The first comparative cytogenetic analysis of three Neotropical woody bamboo species - Guadua chacoensis, G. angustifolia and Chusquea tenella - was undertaken based on new and reviewed chromosome counts, CMA/DAPI double staining, fluorescent in situ hybridization (FISH) with 35S and 5S rDNA probes, and genome size estimation. The two species of Guadua were found to have 2n = 46 chromosomes, while the first record for C. tenella was 2n = 44. Only one pair of CMA+/DAPI- was detected on the terminal region of metacentric chromosomes in all three species. Likewise, one pair of 5S and 35S rDNA sites was detected in all three species, with the 35S rDNA sites always collocated with the CMA+ bands. Genome sizes ranged from 2C ≈ 3.99 pg for the species of Guadua, to 2C = 4.77 pg for C. tenella. Considering the Miocene origin of Neotropical woody bamboos, the observed karyotype stability suggests that the analyzed species are diploidized paleopolyploids. The results reveal the conservative cytomolecular organization of Neotropical woody bamboo karyotypes, which helps to improve our understanding of the evolution of this group.

Highlights

Representing the major clade of grasses with diversification in forest habitats, the bamboos are perennial and multipurpose plants and one of the major non-timber forest products worldwide (Clark et al 2015)
By the new data obtained here, we aimed to address three questions in the woody bamboos: (1) Does cytomolecular data corroborate a paleopolyploid origin of this lineage? (2) What is the degree of diploidization of the analyzed karyotypes? (3) Did the species of Guadua and Chusquea show similar trends in the evolution of the numbers of rDNA sites?
Peterson and G. angustifolia Kunth were obtained from the collection of bamboo species from “Ressacada” Experimental Farm of the Federal University of Santa Catarina (UFSC) (27o41.1’ S; 48o32.63’ O), while Chusquea tenella Nees samples were collected from a natural population at “Ponta do Goulart” locality (27o33.68’ S; 48o31.33’ O), both in Florianópolis, Santa Catarina state (SC), Brazil

Summary

Introduction

Representing the major clade of grasses with diversification in forest habitats, the bamboos (subfamily Bambusoideae) are perennial and multipurpose plants and one of the major non-timber forest products worldwide (Clark et al 2015). Within Bambuseae tribe, two major lineages are recognized [Paleotropical and Neotropical], with Brazil as one of the main centers of diversity and endemism of Neotropical bamboos (Greco et al 2015; Soreng et al 2017). Both belonging to the Bambuseae tribe, the genera Guadua and Chusquea occur from Mexico to Argentina and represent relevant ecological component with economic potential within the Neotropical lineage (Clark et al 2015). Chusquea tenella is a common species of Brazilian Atlantic forest’s understory, frequently associated with altered and endangered environments (Schmidt & Longhi-Wagner 2009)

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