Genetic evidence of multiple reproductive strategies in a microendemic and threatened cactus (Cactaceae: Discocactus Pfeiff) in Bahia, Brazil

Izabela Santos Dias De Jesus,Alessandra Selbach Schnadelbach,Leila Patricio Conceição,José Geraldo De Aquino Assis,Maria Luiza Silveira De Carvalho

doi:10.1590/0102-33062018abb0393

Izabela Santos Dias De Jesus, Alessandra Selbach Schnadelbach + Show 3 more

Open Access

https://doi.org/10.1590/0102-33062018abb0393

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Abstract

ABSTRACT Discocactus zehntneri subsp. petr-halfari, an endangered taxon, is represented by a single population in an anthropized area of Bahia, Brazil, where it is suffering due to extreme extractivism. Thus, information about this cactus, such as its reproductive patterns, is urgently needed to support conservation strategies. A population genetics approach was used to determine if this subspecies has a preferential pattern of reproduction. We sampled 18 individuals, both with and without connection to parental plants, from five clumps and assessed their diversity and genetic structure using five ISSR markers. The results revealed two clumps that are genetically supported by the presence of genetically equal individuals. The other three groups presented individuals that are genetically different and similar to individuals in other clumps. These findings suggest that this subspecies has sexual and clonal reproduction and that its environmental distribution might be shaped by events of dispersion. In addition, a possible hybrid origin may explain its rates of genetic diversity. Despite all these factors, this taxon is in danger and so the development of conservation strategies to preserve its population are urgently needed, including in situ and ex situ actions such as the micropropagation in vitro, living collections and cryopreservation.

Highlights

Discocactus is a genus of the family Cactaceae that occurs in Brazil, Bolivia and Paraguay (Machado 2004; Machado et al 2005); this genus comprises approximately 10 to 25 species, depending on the classification system adopted (Machado 2004; Machado et al 2005; Braun & Esteves 2008; Santos 2013)
The only known population of Discocactus zehntneri subsp. petr-halfari (M.Zachar) M.R.Santos & M.C.Machado occurs in the municipality of Juazeiro, Bahia, Brazil on the margins of highway BR 235 and at an altitude of 350-550 m (9°28’47.6”S 40°15’33.01” W) (Fig. 1A)
The results of this study revealed that three of the analyzed D. zehntneri subsp. petr-halfari clumps presented low to moderate rates of genetic similarity with individuals of the same clumps and high rates with individuals of different clusters, except to PBR4

Summary

Introduction

Discocactus is a genus of the family Cactaceae that occurs in Brazil, Bolivia and Paraguay (Machado 2004; Machado et al 2005); this genus comprises approximately 10 to 25 species, depending on the classification system adopted (Machado 2004; Machado et al 2005; Braun & Esteves 2008; Santos 2013). Discocactus is one of the most critical genera of Cactaceae; its members have a high habitat specificity and live in small populations with limited geographical distribution (Machado et al 2005). No subspecific taxa (as in, subspecies) have been included in this at-risk categorization despite being commonly recognized as such within the genus (Machado 2004; IUCN 2017)

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