Changes in citrus leaf flavonoid concentrations resulting from blight-induced zinc-deficiency

Increased flavonoid concentrations were found to correlate with the elevated levels of leaf phenolic compounds occurring in blight-induced zinc-deficient citrus. In orange (Citrus sinensis L.) leaves, the increases occurred primarily in hesperidin and diosmin, whereas in grapefruit (C. paradisi Macf.) the largest increases occurred in naringin and rhoifolin. Zinc-deficiency occurring in the blighted citrus leaves appeared to be the important contributing factor to the increased flavonoid content. Although the leaves from trees with blight were typically smaller than leaves from unaffected trees, the increased flavonoid content was not significantly due to a concentration effect. Large differences occurred in the percent increases in concentrations of certain citrus leaf flavonoids. While large increases occurred for a number of flavanone and flavone glycosides, much smaller percent increases occurred for other minor flavone glycosides, and the polymethoxyflavone aglycones. The parallel increases occurring in the concentrations of certain flavone glycosides and their flavanone analogs provide a further indication that flavanone glycosides are precursors in the biosynthesis of flavone glycosides in citrus.     

Pollen germination and pollen tube growth in Fraxinus pennsylvanica

With regard to adaptation of green ash (Fraxinus pennsylvanica Marshall) to ecological conditions in Croatia, pollen germination and pollen tube length after 2, 4 and 6 hours were examined in vitro at 10, 15, 20 and 25°C during two years 2001 and 2002. Narrow leaved ash (F. angustifolia Vahl) pollen served as a control in 2002. The year, time and temperature, and the interaction between time and temperature were significant for both germination percentage and pollen tube length. Interactions year × temperature and year × time were significant for pollen tube length only. The highest germination percentage (17.86% in 2001 and 19.40% in 2002) of green ash pollen was at 15°C after 6 hours. The pollen tube length was greatest at 20°C (393.46 μm) in 2001 and 25°C (899.50 μm) in 2002 after 6 hours. Narrow leaved ash pollen had the highest germination percentage (19.22%) at 20°C after 6 hours and was significantly reduced at 25°C. The pollen tube length was greatest at 25°C (518.90 μm) after 6 hours. It can be concluded that green ash pollen has satisfactory germination in ecological conditions in Croatia and that the optimum temperature for pollen germination is higher than 20°C.     

Response of in vitro pollen germination and pollen tube growth of groundnut (Arachis hypogaea L.) genotypes to temperature

Air temperatures of greater than 35 °C are frequently encountered in groundnut‐growing regions, especially in the semi‐arid tropics. Such extreme temperatures are likely to increase in frequency under future predicted climates. High air temperatures result in failure of peg and pod set due to lower pollen viability. The response of pollen germination and pollen tube growth to temperature was quantified in order to identify differences in pollen tolerance to temperature among 21 groundnut genotypes. Plants were grown from sowing to harvest in a poly‐tunnel under an optimum temperature of 28/22 °C (day/night). Pollen was collected at anther dehiscence and was exposed to temperatures from 10° to 47·5 °C at 2·5 °C intervals. The results showed that a modified bilinear model most accurately described the response to temperature of percentage pollen germination and maximum pollen tube length. Genotypes were found to range from most tolerant to most susceptible based on both pollen characters and membrane thermostability. Mean cardinal temperatures (T_min, T_opt and T_max) averaged over 21 genotypes were 14·1, 30·1 and 43·0 °C for percentage pollen germination and 14·6, 34·4 and 43·4 °C for maximum pollen tube length. The genotypes 55‐437, ICG 1236, TMV 2 and ICGS 11 can be grouped as tolerant to high temperature and genotypes Kadiri 3, ICGV 92116 and ICGV 92118 as susceptible genotypes, based on the cardinal temperatures. The principal component analysis identified maximum percentage pollen germination and pollen tube length of the genotypes, and T_max for the two processes as the most important pollen parameters in describing a genotypic tolerance to high temperature. The T_min and T_opt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating genotypes for high temperature tolerance. Genotypic differences in heat tolerance‐based on pollen response were poorly related (R² = 0·334, P = 0·006) to relative injury as determined by membrane thermostability.     

INDUCTION OF ADVENTITIOUS BRANCHES FROM CULTURED CITRUS JUICE VESICLES–A POTENTIAL MEANS OF PROLIFERATION

The noncallusing morphogenetic properties of Citrus juice vesicles cultured in vitro are unknown and were herein studied. Juice vesicles isolated from 120–180-day-old fruits are capable of proliferation via adventitious vesicle branching in vitro. Gibberellic acid levels of 1–100 mg/L greatly enhanced adventitious vesicle branching while delaying vesicle senescence as evidenced by the vesicles' ability to retain its green color for up to 4 to 6 mo in culture. Vesicles grown on media without gibberellic acid readily matured, turning opaque within 2 mo in culture and rarely produced adventitious branches. Additions of 0.1 mg/L α-naphthaleneacetic acid or 1.0 mg/L benzylaminopurine to media containing 10 mg/L gibberellic acid further enhanced vesicle branching in some species and cultivars. Adventitious juice vesicles have been induced from a variety of citrus species, including Citrus grandis (L.) Osb., C. hystrix DC., C. limon (L.) Burm. f., C. medica L., C. paradisi Macf., C. reticulata Blanco, and C. sinensis (L.) Osb. Adventitious vesicle branches originate from primordia initiated on the surface of the cultured vesicle. These primordia commonly occurred on the terminal meristem region of the vesicle. However, some species (e.g., C. grandis and C. paradisi) produced adventitious vesicle branches from their bodies and stalks as well. Distinct vesicle branches begin to appear on preformed vesicles after 30–60 days in culture. A survey to determine the natural occurrence of vesicle branching in various Citrus species was also conducted. Natural vesicle branching commonly occurred in C. grandis, C. paradisi, and in some cultivars of C. reticulata, but was absent in most citrus species and cultivars (e.g., C. aurantifolia (Christm.) Swing., C. canaliculata Hort. ex Y. Tan., C. hystrix, C. limon, C. medica, C. sinensis). It was found that some species which failed to exhibit the adventitious branching phenomenon in nature did so in vitro (e.g., C. hystrix, C. medica, and C. sinensis).     

Isolation of a psychrotolerant Debaryomyces hansenii strain from fermented tea plant (Camellia sinensis) leaves

Abstract

A psychrotolerant, halotolerant and alkalophilic yeast was isolated from fermented leaves of Camellia sinensis Kuntze, the tea plant. The yeast strain, named Tea-Y1, was both phenotypically and genotypically identified as belonging to the species Debaryomyces hansenii. This assignment was confirmed by scanning and transmission electron microscopy. The analysis of growth curves demonstrated the ability this yeast strain to grow in a temperature range between 4°C and 28°C, with an optimum of 23°C. The ecology of this yeast in the C. sinensis phyllosphere, as well as its possible role in tea fermentation and storage, with particular reference to iced tea, are discussed.     

Distribution of overwintering mosquitoes (Diptera: Culicidae) in grassy fields in the Republic of Korea, 2007–2008

Overwintering mosquitoes in a grassy field were surveyed at 13 different localities from December 2007 to February 2008 in the Republic of Korea (ROK). Mosquitoes were collected by putting a white colored tent on the grass, without the base, and heating the inside of the tent. A total of 784 female adults comprising seven species were collected during the study period, including 395 (45.6%) Anopheles pullus, 338 (43.2%) An. sinensis, 21 (2.7%) An. belenrae, 2 (0.3%) An. kleini, 43 (5.5%) Culex tritaeniorhynchus, 20 (2.5%) Cx. inatomii, and 1 (0.3%) Cx. pipiens complex. The mosquitoes showed different overwintering distributions by temperature zone and locality. Predominant species, the malaria vectors An. pullus and An. sinensis, showed different overwintering distributions. Anopheles pullus had a 90.9% collection rate except for Youngju and an average – 0.6°C temperature between December and February. Anopheles pullus showed >50% collection rate in most regions maintained below an average of ?1.4°C, and the rate of An. sinensis showed more than 50% collection rate in all regions maintained at an average above ?1.1°C. Other species showed regional characteristics; An. belenrae was distributed in the northwest part of the ROK, and An. kleini was collected rarely at one locality in the middle part of ROK. Culex tritaeniorhynchus, a Japanese encephalitis virus vector, was distributed in the southern and costal region and maintained at an above average of ?1.0°C. Culex inatomii was collected on the coastal region of the ROK.     

Genetic and nongenetic factors influencing callus induction inMiscanthus sinensis (Anderss.) anther cultures

Miscanthus sinensis is a promising species for biomass production. Influences of genetic and nongenetic factors on androgenesis induction efficiency were investigated. This is the first report on successful induction of pollen-derived callus inM. sinensis. The callus yield was strongly affected by genotype. A beneficial influence of cold pretreatment of spikes on androgenesis induction was observed. The highest yield of calli was obtained in cultures on a modified C17 medium. The results suggest that the high callus yield might be caused by the late culture initiation. The beginning of anther culture at the end of the flowering season caused a 17-fold increase in callus yield, in comparison to culture initiated at the height of the flowering season (August). It is likely, however, that the efficiency of androgenesis induction in the case ofM. sinensis anther culture beginning in October could be related to a positive influence of growing donor plants in conditions of cooler and shorter day, i.e. 11-h day with temperature around 11°C and 13-h night with temperature around 5°C. Results of this study can significantly support the development of effective methods ofM. sinensis haploidization, which could be used in crop improvement by breeding.     

Six new flavonoids from Citrus

Valencia orange (C. sinensis) and Robinson tangerine [(C. paradisi × C. reticulata) × (C. reticulata)] were examined for flavonoids. Thirteen flavonoids were isolated, six of which are new constituents of citrus peel. These are: 3,5,6,7,3′,4′-hexamethoxyflavone, 3,5,7,8,3′,4′-hexamethoxyflavone, 5-hydroxy-3,7,8,3′,4′-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 5,7,8,4′-tetramethoxyflavone and 5,7,8,3′,4′-pentamethoxyflavone. The latter three flavonoids are reported for the first time as natural products. A method is described for readily obtaining small quantities of 5,7,8,4′-tetramethoxy and 5,7,8,3′,4′-pentamethoxyflavones from their 5,6,7-trimethoxy analogs.     

Pollination and seed set in tropical wetland grasses

This study concerns 39 different grass species occurring in the wetland regions of Godavari delta in the west Godavari district (16°15′–17°30′N and 80°50′–81°55′E) of Andhra Pradesh, southern India. In each species, the sexual status of lemmas, the period of stigma receptivity, pollen/ovule ratio, pollen longevity and daily pollen release were examined. The functional sexual systems were determined after performing controlled pollinations and testing seed quality by weight and germination potential. The florets of 35 species are morphologically hermaphroditic. Among the other four species, Chionachne koenigii and Iseilema laxum are monoecious; Chrysopogon aciculatus and Pennisetum pedicellatum are andromonoecious. Examination of the sequential opening of florets and controlled pollinations revealed that C. koenigii and I. laxum are obligate outcrossers with incompatibility to geitonogamous pollen; C. aciculatus and P.pedicellatum have a high level of compatibility to xenopollen. These and another nine species were treated as predominantly outcrossing species. Yet another five species were predominantly self‐fertilized, while the remaining 21 species displayed a mixed breeding system. In a majority of the species the P/O ratios are not high and thus do not conform to the expected large P/O ratios in wind‐pollinated plants and postulated breeding systems except in a few species. The majority of these grasses shed pollen over a short period spreading from 2 am to 8 am, when usually low turbulent conditions exist, thus allowing short distance transport and restricted pollen shadows with higher concentration of pollen near the source. This appears to be the appropriate strategy for maximization of pollination in view of the short lifespan of pollen that extends mostly over 1–3 h period, and the patchy distribution of the grasses under study. The restricted pollen shadows facilitate the low levels of pollen production in the grass species under study to fertilize most or all the available ovules.     

Differing effects of thermal stress on coral fertilization and early embryogenesis in four Indo Pacific species

Coral reefs are expected to be severely impacted by rising seawater temperatures associated with climate change. The fertilization and early embryogenesis of four reef-building coral species representing three Indo-Pacific families were examined in a series of laboratory experiments where temperatures were increased up to 5–6°C at ambient. High levels of fertilization and normal embryogenesis were observed for Favites abdita, Favites chinensis and Mycedium elephantotus at temperatures to 32°C (+5°C) and embryos developed normally until the 5th cell cleavage. Acropora millepora was the only species to be affected by higher temperatures, exhibiting significantly reduced fertilization and a higher frequency of embryonic abnormalities at 32°C (+4°C), and fertilization ceased altogether at 34°C (+6°C). Early cell cleavage rates increased with temperature up to 32°C for all species.     

Winter hardiness of Miscanthus (II): Genetic mapping for overwintering ability and adaptation traits in three interconnected Miscanthus populations

Miscanthus × giganteus (M×g) is the primary species of Miscanthus for bioenergy feedstock production. The current leading biomass cultivar, M×g ‘1993‐1780’, is insufficiently adapted in temperate regions with cold winters such as USDA hardiness zone 5 (average annual minimum temperature of ?28.9 to ?23.3°C) or lower. Three interconnected Miscanthus F₁ populations that shared a common parent were planted in a replicated field trial at Urbana, IL (hardiness zone 5b; average annual minimum temperature of ?26.1 to ?23.3°C) in spring 2011. The winter of 2013–2014 was especially cold in Urbana, with a minimum soil temperature at 10 cm of ?6.2°C and a minimum air temperature of ?25.3°C, giving us an opportunity to evaluate hardiness on established year‐3 plants. The parent in common to all three populations, M. sinensis ssp. condensatus ‘Cosmopolitan’, is native to maritime southern Japan, and in Urbana, it is winter‐damaged most years. In contrast, the three other parents, M. sacchariflorus ‘Robustus’ (MapA), M. sinensis ‘Silberturm’ (MapB), and M. sinensis ‘November Sunset’ (MapC), are typically winter hardy in Urbana. Nearly all MapA progeny plants survived and grew vigorously in spring 2014, whereas in MapB and MapC, many progeny plants did not survive the winter, and most of the survivors were severely damaged, with poor vigor. Negative correlations between overwintering ability and spring regrowth date and autumn dormancy date suggested that the genotypes most likely to survive winters were those that emerged early in spring and/or went dormant early in autumn. Using joint‐population analysis, we identified 53 quantitative trait loci (QTLs) for nine adaptation traits, including nine QTLs for overwintering ability and 11 for spring hardiness scores. Many biologically intuitive candidate genes were observed within or near the QTLs detected in this study, suggesting their validity and potential for further study.     

The role of temperature in enhancing the insecticidal activity of Bacillus thuringiensis against Spodoptera littoralis larvae

The present study scrutinised how far temperature would affect the velocity of the insecticidal activity of Bacillus thuringiensis, as the rapidity of pest control achievements is of a great concern. Third instar Spodoptera littoralis larvae were treated with Bt at three concentration levels under five different temperatures (15°C, 20°C, 25°C, 30°C and 35°C). LT₅₀s were evaluated in each case. The LT₅₀ values showed various levels of reductions as temperature and/or Bt concentration increased, indicating that the velocity of mortality (1/LT₅₀) and/or the rapidity of Bt activity was almost temperature dependant. However, relatively high and low reduction percentages in the LT₅₀ values on the elevation of 5°C were obtained at lower and higher temperature ranges, respectively. The temperature coefficient, Q ₁₀ values, determined within narrow ranges (5°C) showed great reductions when temperature increased from 15°C to 20°C at all Bt concentrations. Raising temperature by 5°C above 20°C or 25°C almost caused similar Q ₁₀ values indicating constant increase in the response of Bt activity within 20–30°C temperature range. Q ₁₀ values over 30°C were comparatively very low. This proved that decrease in Q ₁₀ values due to the rise of temperature was dependant on the starting temperature.     

Production of yellow colour in flowers: redirection of flavonoid biosynthesis in Petunia

Chalcones are intermediates in the biosynthesis of all flavonoids. In addition, in some species they constitute the major yellow flower pigments. There are two types of chalcones, distinguished by the presence (6′-hydroxychalcones) or absence (6′-deoxychalcones) of a hydroxyl group at the 6′ position of the A-ring. The 6′-deoxychalcones are formed when the enzyme chalcone reductase (CHR) is active in conjunction with chalcone synthase (CHS). In Petunia, only 6′-hydroxychalcones are synthesized, and except in the pollen of some genotypes, they are ephemeral intermediates in flavonoid metabolism. By introducing a CHR cDNA from Medicago sativa under the control of the 35S CaMV promoter into acyanic- or cyanic-flowered lines of Petunia, flower colour was changed from either white to pale yellow or deep purple to pale purple, respectively. Lines were generated that accumulated up to 60% of their petal flavonoids as 6′-deoxychalcones. Several different 6′-deoxychalcones accumulated in the petals of the CHR transgenics. The structures of three of these were determined: one, butein 4-O-glucoside, is a novel plant chalcone. Another chalcone compound was identified in the pollen of the transgenics. The results show that the Petunia chalcone isomerase is unable to use 6′-deoxychalcones as substrates so that 6′-deoxychalcones are stable in Petunia petals, leaves and pollen, but some Petunia flavonoid enzymes can use 6′-deoxychalcones as substrates to modify their structures. The introduction of CHR provides a method to redirect the flavonoid pathway into chalcone production, in order to modify flower colour or to reduce the biosynthesis of other flavonoid types.     

Reproduction of the introduced oyster Crassostrea gigas (Bivalvia: Ostreidae) cultured on rafts in Spain

The oyster Crassostrea gigas was introduced in Spain for aquaculture purposes; however, until now, it is not known whether populations are established in the wild, being necessary to define whether this species is spawning and which environmental variables trigger this process. The influence of environmental parameters on the reproduction of C. gigas was evaluated from January 2008 to October 2009 with oysters grown on a raft in the Ría de Arousa (Galicia, NW Spain). Temperature and chlorophyll a are directly correlated to sexual maturation. Oysters can mature at temperatures below 14°C. The temperature necessary for spawning differs between the sexes, requiring a temperature above 15°C for males and 18°C for females. Females had a single massive spawn between June and September, while males had partial spawning from May to December with two peaks, one in May–September and another in October–December, with the second peak more pronounced. The first spawning peak is related to high temperatures and concentrations of chlorophyll a, and the second spawning peak is mainly related to the food availability in the water. The spawning asynchrony may be impeding establishment of wild C. gigas populations in Spain.     

Environmental cues for natural reproduction of the Chinese sturgeon,Acipenser sinensis Gray, 1835, in the Yangtze River,China

For effective conservation, it is important to explore the environmental cues initiating the spawning activities of a fish species. Based on monitoring data gathered between 1998 and 2011, the relationships between spawning activities of the Chinese sturgeon, Acipenser sinensis, and several environmental cues were analyzed using the rare events logistic regression ‘Relogit’ method, which indicated that water temperature, 1‐day ?‐discharge, and atmospheric pressure were among the key spawning cues for A. sinensis (P < 0.05). It is suggested that Chinese sturgeon might have an optimal environment window of 17–20°C water temperature, high day‐to‐day discharge increase, and low atmospheric pressure for spawning. In support of Chinese sturgeon reproduction, suggested modifications to the operational procedures for the Three Gorges Reservoir (TGR) to trigger spawning are: lowering the downstream water temperature to below 20°C before mid‐October and expanding the period with water temperatures of between 17 and 20°C; to create a day‐to‐day intermittent increase in the discharge to an optimal spawning water temperature; and to regulate flow at nights with a low atmospheric pressure.     

Life history and life table parameters of the predatory miceTyphlodromus talbii

The predatory miteTyphlodromus talbii Athias-Henriot occurs in European vineyards and is often associated with economically important species. Neither its role in vineyards nor the factors affecting its population dynamics and relationships with other phytoseiid species are well known. The development and the reproduction ofT. talbii were studied in the laboratory by rearing the predator on different kinds of food (Panonychus ulmi, Eotetranychus carpini, Colomerus vitis, Tydeus caudatus, Mesembryanthemum criniflorum pollen). Overwintered females reared on tydeids survived for long periods and laid eggs, but they died after a few days when spider mites or pollen were provided. Development occurred on all mite species but not on pollen. Developmental times on tydeids were shorter than on the other prey. Oviposition was recorded on tydeids and, to a lesser extent, on eriophyids but not on spider mites or pollen. Experiments on tydeids, which resulted as being the best food, were conducted at two temperatures (20° and 27°C). The highest temperature affected the duration of development and oviposition rates positively, but total fecundity was similar. Predators reared at 27°C consumed more prey than those reared at 20°C. The life table parameters of the species were evaluated onT. caudatus (at 20° and 27°C) and onC. vitis. The highest r_m ofT. talbii was found for individuals reared onT. caudatus at 27°C (0.165). Lower values were obtained on the same prey at 20°C (0.089) or onC. vitis (0.030). The feeding habits ofT. talbii may explain why the species coexists with the generalistAmblyseius aberrans orTyphlodromus pyri.     

Influence of temperature on the in vitro pollen germination and pollen tube growth of various native Iranian almonds (Prunus L. spp.) species

Pollen germination and pollen tube growth was quantified among various native Iranian wild almonds (P. dulcis (Mill.) D. A. Webb, P. eleaegnifolia Mill., P. orientalis Mill., P. lycioides Spach, P. reuteri Bioss. et Bushe, P. arabica Olivier, P. glauca Browick and P. scoparia Spach in order to identify differences in the tolerance of pollen to temperature variations. Pollen germination and pollen tube growth were observed after incubation in darkness in a germination medium for 24?h at 10?C50°C at 5°C intervals. Maximum pollen germination of the wild almond species and specify that 60% was obtained for P. orientalis pollen and 98% for P. scoparia. Pollen tube length ranged from 860???m was obtained in P. lycioides and 1490???m in P. scoparia. A modified bilinear model best described the response to temperature of pollen germination and pollen tube length. Almond species variation was found for cardinal temperatures (T _min, T _opt and T _max) of pollen germination percentage and pollen tube growth. Mean cardinal temperatures averaged over eight almond species were 14.7, 24.2, and 43.7°C for maximum percentage pollen germination and 14.48, 25.3, and 44.4 °C for maximum pollen tube length. The principal component analysis (PCA) identified maximum percentage pollen germination and pollen tube length of the species, and T _max for the two processes as the most important pollen parameters in describing a species tolerance to high temperature. PCA also classified Prunus L. spp. into four groups according to the tolerance of pollen to temperature variations. The T _min and T _opt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating species for high temperature tolerance.     

6,7-Dimethoxycoumarin in the peels of Citrus

6,7-Dimethoxycoumarin was isolated and identified from the peels of Citrus sinensis cv. Pineapple orange, of C. paradisi x C. paradisi x C. reticulata cv. Wekiwa and of C. mitis cv. Clamondin. The coumarin was tentatively identified in two other sweet oranges, C. sinensis cv. Mediterranean Sweet and Waite Parson Brown, and in C. aurantifolia cv. West Indian lime and in C. aurantium cv. Bitter Sweet orange.     

遮阴对柠檬香茅类黄酮及其合成酶基因差异表达研究

为了解柠檬香茅(Cymbopogon citratu)中类黄酮及其合成酶基因信息,以阳光直射及遮阴环境下生长的柠檬香茅嫩叶为材料,进行代谢组、转录组结合qRT-PCR验证分析。结果表明,柠檬香茅中含有11类共69种黄酮化合物,其中芦丁、去甲基托罗沙黄酮、紫云英苷及葡萄糖醇等类黄酮化合物在遮阴环境下相对含量显著降低;类黄酮生物合成涉及10类酶54个基因,其中类黄酮3''羟化酶(c99177.1)等4个酶基因在遮阴环境下相对表达量显著降低,而异黄酮合成酶(c51975.0)等6个酶基因相对表达量正好相反;其中5个类黄酮合成酶基因在光照及遮阴柠檬香茅中的上下调表达趋势与转录组测序结果中FPKM值变化一致,而二者检测结果中差异表达倍数存在差异。遮阴使柠檬香茅中大多黄酮类化合物相对含量降低,而其合成酶基因上下调表达趋势规律不明显。     

Flavonoid and anthocyanin patterns and the systematic relationships in Collomia

Analyses of extracts among populations of the 14 species of Collomia revealed the occurrence of 13 mono-, di- and triglycosides based on the flavonoids, acacetin, kaempferol, patuletin and quercetin. The glycosides included those having arabinose, galactose, glucose and rhamnose as mono-, bio- or triosides at the 3-, 5-, 3,7- or 7-position. Analyses of floral extracts from ten species revealed the occurrence of two anthocyanins, cyanidin and delphinidin 3-(p-coumarylglucosyl)-5-glucoside. Nearly all the species express distinctive flavonoid patterns, although the differences are based on relatively minor changes in position or type of glycosidic substitution. Use of the minimum biosynthetic step distance (MBSD), an index of similarity, revealed that a mean of 5.6 steps separated the 14 species. The four perennial species of section Collomiastrum showed a high degree of similarity and differed consistently from species of the two annual sections Courtoisia and Collomia by lacking quercetin-5-glucoside and kaempferol-3-arabinosylgalactoside. In contrast, flavonoid patterns among species within sections Courtoisia and Collomia showed a relatively low degree of similarity. The dissimilarity between C. diversifolia and C. heterophylla (section Courtoisia) is consistent with their divergent patterns of pollen morphology and ecological distribution. Three groups of species within section Collomia were defined generally by shared patterns of flavonoids, which are correlated to some degree with floral, pollen and vegetative morphology.