Jeffrey B. Harborne’s research while affiliated with University of Reading and other places

6 -H ydroxyflavones have been identified for the first tim e in the Iridaceae, in leaves o f three Crocus species. T hree new glycosides have been characterised: 6 -hydroxyluteolin 7-rham nosylglucoside, scutellarein 7-glucoside and scutellarein 7-m ethyl ether 6 -glucoside, as well as twoknow n glycosides: 6 -hydroxyluteolin 7-glucoside and 6 -hydroxyluteolin 7-m ethyl ether 6 -glucoside. 6 -Hydroxyluteolin and scutellarein glycosides have been found before in Bromeliaceae. Commelinaceae, C yperaceae and O rchidaceae, but this is the first record o f the respective7-m ethyl ethers in the M onocotyledoneae. Acacetin and tricin have been identified asaglycones in C. laevigatus an d C. heuffelianus leaves, respectively and the occurrence o fmangiferin confirm ed in C. aureus leaves. Two o f the m ajor flavonol glycosides present inflowers o f cultivated species were identified as kaem pferol 3-sophoroside and kaem pferol 3-rutinoside-7-glucoside. H ow ever none o f the flavonoids identified appe.

The leaves of 130 species of Rosaceae were surveyed for phytoalexin induction. Both biotic and abiotic induction was examined and antifungal compounds were detected in 47 species. However, these compounds appeared to be constitutive metabolites, released from bound phenolic materials already present in the leaf. In Pyrus, hydroquinone was produced from the hydrolysis of arbutin present in the vacuole before inoculation. In most other species, the fungitoxic agents were mainly catechin-like derivatives, apparently released from the tannins present within the leaf. By contrast, the synthesis in the leaf of the characteristic biphenyl or benzofuran phytoalexins which are produced in sapwood, was confined to a very few species. The biphenyl aucuparin was identified as a phytoalexin from the leaves of Sorbus aucuparia.

Treatment of Gnaphalium vira-vira plants with UV-B radiation caused changes in plant growth and in plant chemistry. The leaf surface contained two O-methylated flavones, araneol and 7-O-methylarancol. HPLC analysis showed that 20 days of UV-B radiation increased the synthesis of 7-O- methylarancol at the expense of araneol. Spectrophotometric analysis of the photosynthetic pigments showed that UV-B radiation also increases the pigment content in treated plants. Another UV alteration is epidermal hair damage, as observed in SEM pictures of treated leaves. This combination of physiological and phytochemical effects may be interpreted as a plant response to UV-B stress.

Lathyrus sativus was investigated for the nature of its phytoalexin response with the result that leaflets, immature pods, andseeds were induced to produce 6a-hydroxy-3-methoxy-8,9-methylenedioxypterocarpan (pisatin). Evidence is presented for the metabolism of pisatin, by the wound pathogen Botrytis cinerea, to a phenolic congener, 3,6a-hydroxy-8,9-methylenedioxypterocarpan.

An electrophoretic survey of anthocyanins in flowers of 81 species belonging to 27 plant families indicated that malonated or similarly substituted zwitterionic anthocyanins occur in half the sample. In particular, almost all species surveyed in the Compositaeand the Labiatae were positive. The same results were also indicated by HPLC separations. Detailed examination of the anthocyanins of Dahlia variabilis and Plectranthus argentatus confirmed the presence of malonylation through glucose. It appears that anthocyanins substituted by aliphatic dicarboxylic acids may be widespread in the angiosperms.

Amentoflavone has been characterised from leaves of Patersonia glabrata. This is the first report of a biflavone in the Monocotyledoneae. The quinone plumbagin, a characteristic constituent of three dicotyledonous families, is now found to be a useful marker for the genus Aristea; it also occurs in two Sisyrinchium species and in Sparaxis tricolor. Mangiferin, a C-glucosylxanthone known previously in the Iridaceae only from Crocus, Iris and Gynandriris has now been found in Eleutherine, Rigidella, Gelasine and Tigridia. results is discussed.

The pterocarpan pisatin has been identified as a major phytoalexin in fifteen species of Lathyrus. Thus, the genus is closer in its phytoalexin response to Pisum than to Vicia, which is known to produce furanoacetylenes on fungal in­ vasion.

Gossypetin 7-methyl ether 3-rutinoside has been characterized as a yellow flower pigment in Ruta graveolens and in five other Ruta species. By contrast, in four Haplophyllum species, the 7-glucoside of gossypetin 3′-methyl ether provides the yellow coloration in the flower. Although carotenoid accompanies the yellow flavonol in R.graveolens, there is no evidence of UV patterning and the petals are uniformly UV absorbing.

In contrast to earlier reports, the major anthocyanin of carrot cells grown in tissue culture has been identified as cyanidin 3-(sinapoylxylosylglucosylgalactoside).It is thus the same as one of the major acylated pigments in the leaf and flower of the whole plant. Daucus carota is therefore not anomalous among higher plants in its anthocyaninsynthesising capacity in callus or shake culture.