Department of Biotechnology & Bioinformatics, Jaypee University of Information Technology, Waknaghat, Solan 173234, HP, India.
J Plant Physiol. 2011 Nov 15;168(17):2117-23. doi: 10.1016/j.jplph.2011.06.018. Epub 2011 Aug 27.
Buckwheat is one of the field crops with the highest concentration of rutin, an important flavonoid of medicinal value. Two species of buckwheat, Fagopyrum esculentum and Fagopyrum tataricum, are the major sources of rutin. Seeds of latter contain 40-50× higher rutin compared to the former. The physiological and molecular bases of rutin content variation between Fagopyrum species are not known. The current study investigated the differences in rutin content in seeds and in other tissues and growth stages of two Fagopyrum species, and also correlated those differences with the expression of flavonoid pathway genes. The analysis of rutin content dynamics at different growth stages, S1-S9 (from seed germination to mature seed formation) of Fagopyrum species revealed that rutin content was higher during seedling stages of F. tataricum (3.5 to 4.6-fold) compared to F. esculentum and then increased exponentially from stages S3 to S6 (different leaf maturing stages and inflorescence) of F. esculentum, whereas it fluctuated in F. tataricum. The rutin content was highest in the inflorescence stage (S6) of both species, with a relatively higher biosynthesis and accumulation during post-flowering stages of F. tataricum compared to F. esculentum. The expression of flavonoid pathway genes, through qRT-PCR, in different growth stages vis-à-vis rutin content variation showed differential expression for four genes, PAL, CHS, CHI and FLS with the amounts of transcripts relatively higher in F. tataricum compared to F. esculentum, thereby, correlating these genes with the biosynthesis and accumulation of rutin. The expression of PAL was highest, 7.69 and 8.96-fold in Stages 2 (seedling stage) and 9 (fully developed seeds) of F. tataricum compared to F. esculentum, respectively. The expression of the CHS gene correlated with the rutin content because it was highest in the flowers (S6) and fully developed seeds (S9) of both Fagopyrum species, with relatively higher transcript amounts (2.13 and 3.19-fold, respectively) in F. tataricum (IC-329457) compared to F. esculentum (IC-540858). This study provides useful information on molecular and physiological dynamics of rutin biosynthesis and accumulation in Fagopyrum species and the correlation of expression of flavonoid biosynthesis genes with the rutin content can be useful in planning for genetic improvement.
荞麦是富含芦丁的大田作物之一，芦丁是一种具有重要药用价值的类黄酮。荞麦有两个种，甜荞（Fagopyrum esculentum）和苦荞（Fagopyrum tataricum），是芦丁的主要来源。后者的种子中芦丁含量比前者高 40-50 倍。荞麦种间芦丁含量变化的生理和分子基础尚不清楚。本研究调查了两种荞麦种（甜荞和苦荞）在种子和其他组织及不同生长阶段芦丁含量的差异，并将这些差异与类黄酮途径基因的表达相关联。分析了两种荞麦种（甜荞和苦荞）在 S1-S9 （从种子萌发到成熟种子形成）不同生长阶段芦丁含量的动态变化，结果表明，苦荞的幼苗期（3.5 到 4.6 倍）芦丁含量高于甜荞，然后从 S3 到 S6 （不同叶片成熟阶段和花序）呈指数增长，而苦荞的芦丁含量则呈波动状态。两种荞麦种的芦丁含量在花序期（S6）最高，在苦荞的开花后阶段（S6）比甜荞相对较高，这表明其在开花后阶段的生物合成和积累较高。通过 qRT-PCR 分析不同生长阶段的类黄酮途径基因表达与芦丁含量变化的关系表明，在四种基因（PAL、CHS、CHI 和 FLS）中存在差异表达，与甜荞相比，苦荞的转录本数量相对较高，从而将这些基因与芦丁的生物合成和积累相关联。PAL 的表达最高，在苦荞的第 2 期（幼苗期）和第 9 期（完全成熟的种子）分别是甜荞的 7.69 和 8.96 倍。CHS 基因的表达与芦丁含量相关，因为它在两种荞麦种的花（S6）和完全成熟的种子（S9）中最高，在苦荞（IC-329457）中的转录本数量相对较高（分别为 2.13 和 3.19 倍），而在甜荞（IC-540858）中较低。本研究为荞麦种芦丁生物合成和积累的分子和生理动态提供了有用的信息，类黄酮生物合成基因的表达与芦丁含量的相关性可用于遗传改良的规划。
