Common buckwheat (Fagopyrum esculentum) is a short-season grain crop that is a source of rutin and other phenolic compounds. In this study, we isolated the cDNAs of 11 F. esculentum enzymes in the flavonoid biosynthesis pathway, namely, phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate:CoA ligase (4CL) 1 and 2, chalcone synthase (CHS), chalcone isomerase (CHI), flavone 3-hydroxylase (F3H), flavonoid 3'-hydroxylase (F3'H), flavonol synthase (FLS) 1 and 2, and anthocyanidin synthase (ANS). Quantitative real-time polymerase chain reaction analysis showed that these genes were most highly expressed in the stems and roots. However, high performance liquid chromatography analysis indicated that their flavonoid products, such as rutin and catechin, accumulated in the flowers and leaves. These results suggested that flavonoids may be transported within F. esculentum. In addition, light and dark growth conditions affected the expression levels of the biosynthesis genes and accumulation of phenolic compounds in F. esculentum sprouts.

Leaves are the final site of salinity perception through the roots. To better understand how wheat chloroplasts proteins respond to salt stress, the study aimed to the physiochemical and comparative proteomics analysis. Seedlings (12-days-old) were exposed to 150 mM NaCl for 1, 2, or 3 days. Na(+) ions were rapid and excessively increase in roots, stems and leaves. Photosynthesis and transpiration rate, stomatal conductance, and relative water content decreased whereas the level of proline increased. Statistically significant positive correlations were found among the content of hydrogen peroxide, activity of catalase, and superoxide dismutase under salt stress in wheat. Protein abundance within the chloroplasts was examined by two-dimensional electrophoresis. More than 100 protein spots were reproducibly detected on each gel, 21 protein spots were differentially expressed during salt treatment. Using linear quadruple trap-Fourier transform ion cyclotron resonance (LTQ-FTICR) hybrid mass spectrometry, 65 unique proteins assigned in the differentially abundant spots. Most proteins were up-regulated at 2 and 3 days after being down-regulated at 1 day. Others showed only slight responses after 3 days of treatment, including Rubisco, glutamate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, isocitrate dehydrogenase, photosystem I, and pyridoxal biosynthesis protein PDX1.2 and PDX1.3. The ATP synthase (α, β, and γ) and V-type proton ATPase subunits were down-regulated resulting showed negative impact by Na(+) on the photosynthetic machinery. This ephemeral increase and subsequent decrease in protein contents may demonstrate a counterbalancing influence of identified proteins. Several proteins such as cytochrome b6-f (Cyt b6-f), germin-like-protein, the γ-subunit of ATP synthase, glutamine synthetase, fructose-bisphosphate aldolase, S-adenosylmethionine synthase, carbonic anhydrase were gradually up-regulated during the period of treatment, which can be identified as marker proteins.

Six genes involved in anthocyanin biosynthesis in tartary buckwheat have been cloned, namely, FtC4H, Ft4CL, FtCHI, FtF3H, FtF3'H, and FtANS, which encode cinnamate 4-hydroxylase (C4H), 4-coumarate:CoA ligase (4CL), chalcone isomerase (CHI), flavones 3-hydroxylase (F3H), flavonoid 3'-hydroxylase (F3'H), and anthocyanidin synthase (ANS), respectively. Then, these cDNAs were used, along with previously isolated clones for phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS), to compare gene expression in different organs, flowering stages, and maturing seeds of tartary buckwheat cultivars 'Hokkai T8' and 'Hokkai T10'. Quantitative real-time polymerase chain reaction analysis showed that these anthocyanin biosynthetic genes were most highly expressed in the stems and roots of Hokkai T10. The FtANS gene was more highly expressed than other genes during flowering and maturing seeds. In addition, the anthocyanin concentration was higher in 'Hokkai T10' than in 'Hokkai T8'; however, naringenin chalcone, a flavonoid, was absent from 'Hokkai T10' seedlings based on fluorescence microscopy.

. 1999. Inheritance of self-compatibility and flower morphology in an inter-specific buckwheat hybrid. Can. J. Plant Sci. 79: 483-490. This study was conducted to determine the inheritance of selfcompatibility and homomorphic flower type when the wild species Fagopyrum homotropicum was crossed with common buckwheat (F. esculentum). Unidirectional interspecific hybrids between cultivated F. esculentum Moench. (common buckwheat) and its wild relative F. homotropicum were produced after controlled pollination and embryo rescue culture. Cross-compatibility was found to be better when thrum-type common buckwheat was used as the female parent rather than the pin-type. The resulting F 1 plants were partially fertile, late maturing and intermediate between the parents in flower shape and plant height. They segregated into heterostylic (thrum only) and homostylic types in equal numbers, indicating that homostyly is controlled by a single dominant gene. The thrum-type F 1 hybrids were backcrossed to common buckwheat and the progenies were raised utilizing embryo rescue culture. The homostylic F 1 hybrids were advanced to the F 2 and F 3 generations through self-fertilization and utilized, together with the BC 1 F 1 , for the analysis of the stylar genes. The results obtained indicate that the genes coding for heterostyly and homostyly are controlled by the multiple allelic gene S. It appears that the pin/thrum complex in F. esculentum is governed by a single genetic locus S with two alleles S and s that control the reaction in Ss (thrum-type) as well as the ss (pin-type) plants, respectively. The homomorphic flower type of F. homotropicum is governed by the allele S h. . These genes can be characterized by a relationship of dominance, i.e. S > S h > s. The introgression of F. homotropicum genes into common buckwheat was verified by means of electrophoretic analysis of seed proteins.

The buckwheat plant contains high levels of rutin (flavonol 3-O-rutinoside) in many organs, including its seeds, cotyledon, leaves, stem, and flowers. The enzymes that catalyze the decomposition and synthesis of rutin in buckwheat are unique in terms of having relatively low K m values, indicating that buckwheat developed rutinosidase and glycosyl transferase enzymes specifically suited for rutin metabolism. In Tartary buckwheat seeds, high levels of rutin content and rutinosidase activity cause strong bitterness, which may effectively protect the seeds from being eaten by animals. The stress responses observed in buckwheat leaves suggests that rutin and rutinosidase are involved in enhancing the defense system against environmental stresses, including UV light, low temperature, and desiccation.