Genome size in Bituminaria bituminosa (L.) C.H. Stirton (Fabaceae) populations: separation of ȁc;true” differences from environmental effects on DNA determination

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• 作者：David J. Walker ; Inmaculada Moñ ; ino and Enrique Correal
• 关键词：Bituminaria bituminosa (L.) C.H. Stirton (syn. Psoralea bituminosa L.) ; Flow cytometry ; Fluorochrome interference ; Intraspecific variation ; Nuclear DNA ; Secondary metabolites
• 刊名：Environmental and Experimental Botany
• 出版年：2006
• 出版时间：March 2006
• 年：2006
• 卷：55
• 期：3
• 页码：258-265
• 全文大小：126 K

文摘

Bituminaria bituminosa (L.) C.H. Stirton (Fabaceae) is a perennial legume of interest due to its use as a feed for livestock and its contents of furanocoumarins. Nuclear DNA contents of six populations of B. bituminosa, originating from mainland Spain (2), the Canary Islands (3) or Sardinia (1), were determined. Flow cytometry was used to estimate the 2C nuclear DNA contents of the selected populations, using leaf material from plants grown under field conditions in Southern Spain and analysed in December 2002, April 2003 and August 2003. For December and April, apparent mean values ranged from 0.998 to 1.121 pg, with Canarian populations exhibiting values lower than those from mainland Spain or Sardinia. Thus, there was true intraspecific variation in nuclear DNA content, related to the geographic origin of the populations and irrespective of environmental factors, for B. bituminosa. The mean nuclear DNA content was correlated significantly (P < 0.05) with the longitude (°E) and the mean temperature (°C) of the warmest month at the sites from which the populations originated. Except for the population from Mijas (mainland Spain), the estimates of nuclear DNA made using leaves collected in August (summer; average daily maximum temperature 35–36 °C) were significantly lower (by between 3.8 and 7.4 % ) than those obtained in December (winter; average daily maximum temperature 18–21 °C). This environmentally induced (artefactual) variation within populations, with apparent decreases in summer, may have been due to interference from leaf furanocoumarins, which are known to accumulate to a greater extent at higher temperatures. The results highlight the care that must be taken in the critical estimation of nuclear DNA contents by flow cytometry, particularly for species such as B. bituminosa which are capable, according to the environmental conditions, of accumulating significant amounts of secondary compounds.