Prediction of Lime Tolerance in Rhododendron Based on Herbarium Specimen and Geochemical Data.

Johan Van Huylenbroeck,Shusheng Wang,Leen Leus,Marie-Christine Van Labeke

doi:10.3389/fpls.2018.01538

Abstract

Rhododendrons are typically known to be calcifuges that cannot grow well in lime soils. Data on lime tolerance of different taxa in Rhododendron are scarce. Habitats of naturally distributed specimens of genus Rhododendron were compiled as Chinese text-based locations from the Chinese Virtual Herbarium. The locations were then geocoded into latitude/longitude pairs and subsequently connected to soil characteristics including pH and CaCO3 from the Harmonized World Soil Database (HWSD). Using the upper quartile values of pH > 7.2 and CaCO3 > 2% weight in topsoil as threshold, we predicted the lime tolerant taxa. A dataset of 31,146 Rhododendron specimens including the information on taxonomy, GPS locations and soil parameters for both top- and subsoil was built. The majority of the specimens were distributed in soils with moderately acidic pH and without presence of CaCO3. 76 taxa with potential lime tolerance were predicted out of 525 taxa. The large scale data analysis based on combined data of geocoded herbarium specimens and HWSD allows identification of valuable Rhododendron species, subspecies or botanical varieties with potential tolerance to lime soils with higher pH. The predicted tolerant taxa are valuable resources for an in-depth evaluation of lime tolerance or for further use in horticulture and breeding.

Highlights

The tolerance of various plant species to abiotic stresses evolves according to environmental changes in their habitats (Dimichele et al, 1987; Amtmann et al, 2005; Marais and Juenger, 2010)
The locations of 35,574 specimens were geocoded to Global Position System (GPS) latitude/longitude pairs with a labeled text that best matched the location text of specimen
Our results showed that information present in herbarium specimens might be used to identify potentially interesting genetic resources in Rhododendron

Summary

Introduction

The tolerance of various plant species to abiotic stresses evolves according to environmental changes in their habitats (Dimichele et al, 1987; Amtmann et al, 2005; Marais and Juenger, 2010). The evolutionary processes influenced by environmental change as well as the modern regionalization and dispersal of natural habitats have resulted in diverse biogeographical distribution patterns among different plants (Wen, 1999; Xing et al, 2015). Predicting plant species’ tolerance to abiotic stresses using distribution and geochemical data has been accepted as a potentially useful approach (Saslis-Lagoudakis et al, 2015). Collection of largescale distribution data of plants through field study is time-consuming. An alternative method of extracting the distribution information from the specimens in herbaria, which were collected and identified by botanists and experienced plant hunters including the location data, is effective and meaningful (Hart et al, 2014; Romeiras et al, 2014; Zhang et al, 2015).

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