Spatial genetic structure of lowbush blueberry,Vaccinium angustifolium, in four fields in Maine

Abstract

Expressed sequence tag -polymerase chain reaction (EST-PCR) molecular markers were used to infer spatial genetic structure of four lowbush blueberry (Vaccinium angustifolium Ait.) fields in Maine. Genetic structure was quantified at three spatial scales: (1) within apparent clones (intrapatch), (2) among clones within a field, and (3) among fields separated by as much as 65 km. Of five ''clones'' or putative individuals examined in the intrapatch study, two showed complete genetic homogeneity within the patch, while three showed some band differences at their edges compared with their interiors. These differences at the edges, however, matched adjacent clones (so-called ''intruders''), from which it was concluded that lowbush blueberry exhibits a fairly tight, phalanx clonal architecture with no evidence of invasive seedling establishment within clones. No significant correlation between genetic and physical distance was found among clones within fields via several statistical approaches. Significant among-field genetic differentiation was found via AMOVA (FPT = 8.4%; p 0.01) based upon transect samples across four fields ranging from 12.5 to 65 km apart. Principal component analysis and spatial autocorrelation (SA) corroborated these findings. Significant positive SA was found at the within-field distance class of <350 m, but SA decreased to an insignificant value by the first interfield distance of 12.5 km. A special form of SA analysis was employed to detect ''hotspots'' of genetic similarity between pairs of adjacent clones in two fields. Results indicated that 5 of 23 pairs of clones (21.7%) were genetically similar to each other, while the majority of pairs (18 of 23; 78.3%) showed random, decreasing patterns of genetic similarity. Results are discussed in terms of clonal dynamics including architecture, seedling recruitment, and inferred pollen or seed dispersal distances.Résumé : Les auteurs ont utilisé des marqueurs moléculaires EST-PCR (étiquette de séquence exprimeé -réaction en chaîne de la polymérase) pour déduire la structure génétique spatiale de quatre champs de bleuets (Vaccinium angustifolium Ait.), du Maine, aux É tats-Unis. Ils ont quantifié la structure génétique à trois échelles spatiales: (1) dans les clones apparents (dans les talles), (2) entre les clones d'un même champ et (3) entre des champs séparés jusqu'à 65 km. Dans l'étude, sur cinq « clones » apparents ou présumés individus examinés, deux montrent une complète homogénéité géné-tique dans la talle, alors que trois montrent quelques différences de bandes à leur pourtour comparativement à leurs centres. Cependant, ces différences aux pourtours correspondent à des clones adjacents nommés « intrus », ce qui permet de conclure que le bleuet nain montre une architecture clonale de type phalanx assez serrée, sans trace d'établissement de plantules invasives dans les clones. On ne trouve aucune corrélation significative pour les distances génétiques et géogra-phiques entre les clones d'un même champ, selon plusieurs approches statistiques....

Genetic Diversity of Lowbush Blueberry throughout the United States in Managed and Non-Managed Populations

“…Forests are harvested and the existing understory blueberry plants become established.The underlying genetic diversity of lowbush blueberry is relatively unknown compared to other fruit crops [8]. Recently, a variety of techniques and molecular markers have been used to investigate the genetic heterogeneity and relatedness of V. angustifolium populations [1,8,[10][11][12][13][14][15]. These studies have shown V. angustifolium to be highly diverse in Maine and the Canadian Maritimes.…”

Mitigation of pollen limitation in the lowbush blueberry agroecosystem: effect of augmenting natural pollinators

“…Paired shoots were determined to originate from the same clone by following the shoot to the crown of the clone. Clones were also differentiated from one another based on morphology and growth pattern (Bell et al 2009). For each clone two pollination treatments were compared: (1) an open-pollinated inflorescence (i.e., pollinated by managed and native pollinators present in the field), and (2) an inflorescence supplementally pollinated by hand with outcross pollen collected from a separate clone located at least 5 m away from the experimental transect (Table 1).…”

“…However, the large clone size of lowbush blueberry (commonly 2-10 m in diameter; Bell et al 2009, Bobiwash et al 2013) and the simultaneous display of thousands flowers on a clone increases the likelihood of selfpollen transfer by pollinators that forage on flowers within a clone (Eckert 2000, Charpentier 2001, Barrett 2002, 2003, and so it is unclear whether augmenting numbers of native pollinators by introducing non-native pollinators, as commonly practiced by growers, is sufficient to increase yields.…”

Evidence of functional gender polymorphisms in a population of the hermaphroditic lowbush blueberry (Vaccinium angustifolium)1This article is part of a Special Issue entitled “A tribute to Sam Vander Kloet FLS: Pure and applied research from blueberries to heathland ecology”.

“…Natural dispersal of both pollen (bees) and seed (birds and bears) has resulted in the pronounced patterns of genetic diversity evident today. The species is highly polymorphic at the morphological, physiological, and molecular levels (Vander Kloet 1978;Bell et al 2008Bell et al , 2009). Lowbush blueberry is, to a large extent, self-infertile (Aalders and Hall 1961); however, the degree of self-fertility can vary greatly among individuals (Wood 1968;Bell et al 2010).…”

“…If, indeed, some clones are functioning as males and produce few ovules or seed, this could be an additional explanation for variations in clonal yield, a topic that we have been studying for several years (Bell 2009;Bell et al 2010). For male fertility, we measured the same trait as Myra (2004), viable microspores per flower (number of pollen tetrads per flower × 4 × proportion pollen viability).…”