ARCHAEOBOTANICAL STUDIES OF ELEUSINE CORACANA SSP. CORACANA (FINGER MILLET)

Two controversial archaeological specimens of finger millet, Eleusine coracana ssp. coracana (L.) Gaertn., were examined by light and scanning electron microscopy. Identification of the material was based on morphological and anatomical comparison with laboratory carbonized grains of modern Eleusine. Seed morphology of the Indian archaeological collection did not conform with those of domesticated or wild species of Eleusine. The other archaeological collection examined is from Ethiopia. It is estimated to date back to the third millennium B.C. These well preserved inflorescence fragments were positively identified as finger millet. If the suggested date is correct, they represent the oldest archaeological record for the crop, as well as the oldest agricultural record for Africa south of the Sahara. These findings support biosystematic evidence for an East African origin of finger millet which leaves India as a secondary center of diversity.     

SYSTEMATICS AND EVOLUTION OF ELEUSINE CORACANA (GRAMINEAE)

Finger millet (Eleusine coracana (L.) Gaertn. subsp. coracana) is cultivated in eastern and southern Africa and in southern Asia. The closest wild relative of finger millet is E. coracana subsp. africana (Kennedy-O'Byrne) Hilu & de Wet. Wild finger millet (subsp. africana) is native to Africa but was introduced as a weed to the warmer parts of Asia and America. Derivatives of hybrids between subsp. coracana and subsp. africana are companion weeds of the crop in Africa. Cultivated finger millets are divided into five races on the basis of inflorescence morphology. Race coracana is widely distributed across the range of finger millet cultivation. It is present in the archaeological record of early African agriculture that may date back 5,000 years. Racial evolution took place in Africa. Races vulgaris, elongata, plana, and compacta evolved from race coracana, and were introduced into India some 3,000 years ago. Little independent racial evolution took place in India.     

Agrobacterium-mediated transformation of finger millet (Eleusine coracana (L.) Gaertn.) using shoot apex explants

A new Agrobacterium-mediated transformation system was developed for finger millet using shoot apex explants. The Agrobacterium strain LBA4404 harboring binary vector pCAMBIA1301, which contained hygromycin phosphotransferase (hptII) as selectable marker gene and β-glucuronidase (GUS) as reporter gene, was used for optimization of transformation conditions. Two finger millet genotypes, GPU 45 and CO 14, were used in this study. The optimal conditions for the Agrobacterium-mediated transformation of finger millet were found to be the co-cultivation of explants obtained on the 16th day after callus induction (DACI), exposure of explants for 30 min to agrobacterial inoculum and 3 days of co-cultivation on filter paper placed on medium supplemented with 100 μM acetosyringone (AS). Addition of 100 μM l-cysteine in the selection medium enhanced the frequency of transformation and transgenic plant recovery. Both finger millet genotypes were transformed by Agrobacterium. A frequency of 19% transient expression with 3.8% stable transformation was achieved in genotype GPU 45 using optimal conditions. Five stably transformed plants were fully characterized by Southern blot analysis. A segregation analysis was also performed in four R₁ progenies, which showed normal Mendelian pattern of transgene segregation. The inheritance of transgenes in R₁ progenies was also confirmed by Southern blot analysis. This is the first report on Agrobacterium-mediated transformation of finger millet. This study underpins the introduction of numerous agronomically important genes into the genome of finger millet in the future.     

Experimental approaches to understanding variation in grain size in Panicum miliaceum (broomcorn millet) and its relevance for interpreting archaeobotanical assemblages

The dimensions of archaeobotanical grains identified as Panicum miliaceum (broomcorn millet) vary greatly in size. This is illustrated by the remains from the archaeological site of Zanovskoe in eastern Ukraine (5th–1st centuries cal. b.c.). We carried out experimental work on broomcorn millet plants and grains, aiming at a comprehensive understanding of factors that may have contributed to variation in the grain size of broomcorn millet in archaeobotanical assemblages. We analyzed the dependence of grain size variation on selected environmental and taphonomic factors. Our results indicate that immaturity is more likely than environmental stress to account for small grain size in broomcorn millet plants. Depending on charring temperature and time, immature broomcorn millet grains can withstand charring and are potentially preserved in archaeological assemblages. Depending on maturity level, such grains vary in size and shape. These results are potentially important for accurate identification of archaeobotanical specimens.     

Early plant domestications in southern India: some preliminary archaeobotanical results

Analysis of flotation samples from twelve sites in Karnataka and Andhra Pradesh (south India) provides clear evidence for the predominant subsistence plants of the Neolithic period (2,800–1,200 cal b.c.). This evidence indicates that the likely staples were two pulses (Vigna radiata and Macrotyloma uniflorum) and two millet-grasses (Brachiaria ramosa and Setaria verticillata) which were indigenous to the Indian peninsula. At some sites there is evidence for limited cultivation of wheats (Triticum diococcum, Triticum durum/aestivum) and barley (Hordeum vulgare), and a few crops that originated in Africa, including hyacinth bean (Lablab purpureus), pearl millet (Pennisetum glaucum) and finger millet (Eleusine coracana). In addition there is evidence for cotton (Gossypium sp.), and linseed (Linum sp.), as well as gathered fruits of Ziziphus and two Cucurbitaceae. This evidence suggests that the earliest agriculture in south India, dating to the third millennium b.c., was based on plants domesticated in the region, and that subsequently from the late 3^rd millennium b.c. through the 2^nd millennium additional crops from other regions were adopted into the subsistence system.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00334-004-0036-9     

T’ef (<Emphasis Type="Italic">Eragrostis tef</Emphasis>) in Ancient Agricultural Systems of Highland Ethiopia

T’ef ( Eragrostis tef ) in Ancient Agricultural Systems of Highland Ethiopia. T’ef (Eragrostis tef) has been cultivated in the Horn of Africa for at least 2,000 years. The earliest known agricultural systems in this region date to the Pre-Aksumite period (800–400 b.c.) and appear to have focused on Near Eastern crops, with indigenous African species increasing in importance during Aksumite times (400 b.c.–a.d. 700). While palaeoethnobotanical data are available from Pre-Aksumite and late Aksumite periods, macroscopic botanical remains from the site of Ona Nagast, northern Ethiopia, provide a first glimpse of agricultural systems dating to Proto-Aksumite (400–50 b.c.), Early to Classic (50 b.c.–a.d. 340), and Post-Aksumite (a.d. 700–900) times. Archaeological t’ef remains from Ona Nagast are examined in detail. Guidelines are developed for the identification of t’ef grains preserved on archaeological sites, with a focus on how to differentiate them from seeds of wild Eragrostis species. Charring experiments reveal that in some cases t’ef may not survive high temperatures tolerated by larger cereal grains, such as wheat and barley. The domestication history of t’ef appears to be different from some other cereals, a factor which may explain the preponderance of indeterminate Eragrostis seeds in archaeological samples. Selection of large seed size and intensified tillage were not key factors in t’ef domestication. Early cultivators were likely selecting for increased branching and higher percentage seed set under conditions of minimal tillage.     

Late Neolithic agriculture in eastern Austria: archaeobotanical results from sites of the Baden and Jevišovice cultures (3600–2800 b.c.)

The article presents archaeobotanical results from six late Neolithic excavation sites in eastern Austria. Two of the sites belong to the Jevišovice culture (3200–2800 cal b.c.), the remaining four to the Baden culture (3600–2900 cal b.c.). Results show that farmers around 3000 cal b.c. were relying on the use of Triticum monococcum and Hordeum vulgare as principal cereals, with Triticum dicoccum and Panicum miliaceum as additional crops. Common millet was found in quantity at one of the Jevišovice sites and shows the remarkably early westward spread of this species. Single records of Triticum spelta are discussed in the light of the recently proposed ideas about an independent central European origin of spelt. Another record concerns the “new-type” glume wheat, providing further evidence for the once widespread occurrence of this cultivar. Triticum aestivum (hexaploid naked wheat) and Setaria italica (foxtail millet) were found as rare admixtures at the Jevišovice settlements. Pulses were represented by Pisum sativum and Lens culinaris, oil plants by Papaver somniferum and Linum usitatissimum. One of the Jevišovice sites offered a good opportunity for a study of the undisturbed spatial distribution of charred plant remains within a burnt house. Among wild plants, the occurrence of Stipa sp., Teucrium chamaedrys, Asperula cynanchica and Plantago media point to the presence of dry steppe grassland in the vicinity of the settlements, which was probably used for grazing. Woodland plants were mainly represented by fruit-bearing plants growing in clearings and forest edges, reflecting both the deliberate collection of wild fruits and the growing human impact on the vegetation.     

Retting pits for textile fibre plants at Danish prehistoric sites dated between 800 b.c. and a.d. 1050

During the last decade, a new type of structure has been found at several archaeological sites in Denmark. These structures can be interpreted as having been used for retting the stems of textile plants such as Linum usitatissimum L. (flax), Cannabis sativa L. (hemp) and Urtica dioica L. (nettle). In order to obtain fine threads for textile production, these plants need to pass through several biological and technical processes. The first process is the retting of the plant stems to dissolve the pectin which fixes the fibres to the stalk. This can either be done by water retting, where the plant stems are soaked in lakes, rivers or waterlogged pits, or by field retting, where the stems are laid out in a field in order to absorb dew. The first method is shorter in time and the process is easier to control. In this article, details of archaeological structures are presented from eight sites in southern Scandinavia that can be interpreted as textile plant retting pits. The constructions of the pits are described, as well as the archaeological contexts and the relevant associated archaeobotanical records. Some of the presented sites, of which the oldest are dated to the late Bronze Age and early pre-Roman Iron Age (800–250 b.c.) and the youngest to the Viking Age (a.d. 750–1050), indicate a large-scale production of flax that had been underestimated up to now.     

Plant use at an early Islamic merchant town in the West African Sahel: the archaeobotany of Essouk-Tadmakka (Mali)

We present archaeobotanical data from the early Islamic era (ca. a.d. 750–1400) obtained from excavations at Essouk-Tadmakka, an important trans-Saharan trading town site in the West African Sahel and an early centre of the Tuareg. The paper provides insight into a little researched area of arid zone medieval West Africa and presents practically the only substantive archaeobotanical evidence of the medieval Tuareg. The evidence firstly enables us to shed greater light on the Arabic historical references to traditions of wild cereal gathering at Essouk-Tadmakka. It also establishes the presence at the site of a range of important taxa, including pearl millet, date, balanites, cotton and linseed, as well as a host of other fruits, legumes (Fabaceae) and wild plants. Perhaps the most striking finding is the earliest and largest archaeobotanical data set for wheat in West Africa. In addition to providing the first archaeobotanically based discussion of Essouk-Tadmakka’s gathering traditions, agriculture, and grain importation, we also seek to highlight certain evidence for change over time in the archaeobotany recovered. The data seems to suggest that towards the end of the site’s occupation (ca. a.d. 1300) there was a shift to increased presence of fruit and legumes and more limited presence of cereals, and we attempt to relate this to wider shifts in Sahelian culture at this time.     

Domestication ofEleusine coracana

Eleusine coracana (L.) Gaertn. subsp.coracana (Finger millet or eleusine) is a cereal that is widely cultivated in Africa and India. Archaeological records of finger millet are few and unsatisfactory. But, distribution, linguistic and historical evidence seem to suggest an African rather than Indian origin of the crop. Data from morphology, supplemented with cytogenetical observations and distribution revealed thatE. coracana subsp.africana is wild finger millet. This subspecies is widely distributed along the highlands of East Africa. Consequently, it is concluded that finger millet originated in the East African Highlands and was subsequently introduced into India.     

Finger Millet processing in East Africa

Although archaeobotanical sampling and recovery programmes are a relatively recent implementation in East African archaeology, results from sites where they have been carried out follow a similar trend. This is one of abundant recovery of wood charcoal, but very little in the way of other macroscopic plant remains. Restricted archaeological evidence and ethnographic interviews show the importance of grains, in particular finger millet (Eleusine coracana), for the Bunyoro people of Uganda in pre-colonial times. It has been suggested that one of the possible reasons why finger millet is not being recovered in quantity from archaeological contexts is because the processing of this crop does not involve heating and hence there is not the chance of being deposited in charred form in the archaeological record. Recent ethnographic work on finger millet processing in Uganda shows that it is exposed to heat and potential charring during cleaning and preparation of the grain for either storage or cooking, and this regime is discussed in terms of its activities and products. These findings reinforce the need for archaeobotanists and archaeologists working in this region to look for other possible causes of the scarcity of macroscopic plant remains, and also the importance of considering integrated evidence for agricultural activity on prehistoric sites.     

Vegetation history and agriculture in the cover-sand area west of Breda (province of Noord-Brabant, The Netherlands)

Botanical investigation of archaeological sites situated in the northwest of the region bounded by the rivers Maas, Scheldt and Demer (‘MSD region’), west of the city of Breda, has provided a great deal of evidence about the landscape and its use in the period between 2000 b.c. and a.d. 1500. From pollen analysis, it appears that this cover-sand area gradually lost its woodlands through human activity after the beginning of the Bronze Age (ca. 2000 b.c.). Patches of woodland did survive there, however, until the early Middle Ages. In contrast to the cover-sand area in the vicinity of ’s-Hertogenbosch and Oss-Ussen in the northeast of the MSD region, the first large heathlands in the Breda area did not evolve until the early Middle Ages. In late prehistory, land use in this area was not much different from that in the micro-region of ’s-Hertogenbosch and Oss-Ussen. In the Bronze Age, Hordeum vulgare ssp. vulgare (hulled six-row barley) and Triticum dicoccon (emmer wheat) were grown. During the Iron Age, Panicum miliaceum (common millet) and T. spelta (spelt wheat) were introduced, but these crops disappeared during the Roman period. The Roman period is remarkable because of the lack of any Mediterranean culinary herbs or exotic fruits. Only pollen of Juglans regia (walnut), found around the transition from the Roman period to the early Middle Ages, indicates the introduction of an exotic tree into the region. From the early Middle Ages onwards, Secale cereale (rye) was the most important cereal, which was grown as a winter crop. In the course of the Middle Ages, arable weeds of the Sclerantho annui-Arnoseridetum plant community appeared, which is associated with the continuous growing of rye.     

Mid- and late-Holocene vegetation and fire history at Biviere di Gela, a coastal lake in southern Sicily, Italy

The vegetation and fire history of few coastal sites has been investigated in the Mediterranean region so far. We present the first paleoecological reconstruction from coastal Sicily, the largest island in the Mediterranean Sea. We analysed pollen and charcoal in the sediments of Biviere di Gela, a lake (lagoon) on the south coast of Sicily. Our data suggest that the area became afforested after a marine transgression at ca. 7200 cal b.p. (5250 b.c.). Build-up of forest and shrublands took ca. 200–300 years, mainly with the deciduous trees Quercus, Ostrya and Fraxinus. Juniperus expanded ca. 6900 cal b.p. (4950 b.c.), but declined again 6600 cal b.p. (4650 b.c.). Afterwards, evergreen trees (Q. ilex-type and Olea) became dominant in the forest and Pistacia shrublands were established. Forest and shrubland reached a maximum ca. 7000–5000 cal b.p. (5050–3050 b.c.); subsequently forest declined in response to human impact, which was probably exacerbated by a general trend towards a more arid climate. During the Neolithic, fire was used to open the landscape, significantly reducing several arboreal taxa (Q. ilex, Fraxinus, Juniperus) and promoting herbs and shrubs (Achillea, Cichorioideae, Brassicaceae, Ephedra). Final forest disruption occurred around 2600 cal b.p. (650 b.c.) with the onset of the historically documented Greek colonization. We conclude that the open maquis and garrigue vegetation of today is primarily the consequence of intensive land-use over millennia. Under natural or near-natural conditions arboreal taxa such as Q. ilex, Olea and Pistacia would be far more important than they are today, even under the hot and rather dry coastal conditions of southern Sicily.     

Farmers’ Management of Finger Millet (Eleusine coracana L.) diversity in Tigray, Ethiopia and Implications for on-Farm Conservation

Tigray (region) is one of the major finger millet growing regions in Ethiopia and an important site from an archeobotanical point of view. Three zones of Tigray (east, central and west) were identified as representative sites in the region and a total of 14 districts/ ‘Woreda’ were surveyed. Thirty-seven landraces/farmers’ varieties of finger millet were identified/recorded. Farmers in Tigray undertake pre and post harvest selection in finger millet and sometimes they also select seeds from storage based on a number of attributes. Farmers maintain diversity as a way to ensure harvest security or stability of production, to promote diversity of diet and income sources, minimize crop failure risk, reduce insect and disease incidences and ensure efficient use of labour. The traditional management of finger millet in the entire study area is generally found to be demand driven, showing the existence of potential sites for on-farm conservation. The high morphological diversity (H =0.76 ± 0.09) found in the gene bank collections of Tigrayan origin also reveals the importance of linking ex situ with in situ conservation activities. Furthermore, the enhancement and conservation significance of the crop is discussed.     

Four thousand years of plant exploitation in the Lake Chad Basin (Nigeria), part III: plant impressions in potsherds from the Final Stone Age Gajiganna Culture*

Late Holocene climatic changes caused a large scale regression of the Lake Chad shoreline followed by an expansion of settlements into previously unexplored territories. Numerous Final Stone Age sites of the Gajiganna Culture (1,800 to 800 b.c.) in the Lake Chad Basin (northeast Nigeria) yielded plant impressions in potsherds. The ceramics of Phase I (1,800–1,400 b.c.) were mineral tempered, and plant impressions, mainly of Paniceae, were caused only by incidental inclusion. In contrast, a considerable number of the sherds from Phase II (1,500–800 b.c.) were intentionally tempered with chaff derived from domesticated pearl millet (Pennisetum glaucum), wild Paniceae and wild rice species (Oryza cf. barthii and O. cf. longistaminata). This plant spectrum suggests the exploitation of the wet wild areas, and also the cultivation of pearl millet on sandy soils. The evidence suggests that agricultural practices were established late and were introduced from elsewhere. During the time of seasonally occupied sites in Phase I, the subsistence strategy was based on herding, fishing, and gathering, while in Phase II there are signs of permanent settlements and agriculture. The evidence from the plant impressions indicates that in the Final Stone Age Gajiganna Culture around 1,000–800 b.c., pearl millet became well established while the gathering of wild millets and rice was still practised.*Klee et al. (2000), Zach and Klee (2003)     

Membrane Potassium Channels and Human Bladder Tumor Cells. I. Electrical Properties

These experiments were conducted to determine the membrane K⁺ currents and channels in human urinary bladder (HTB-9) carcinoma cells in vitro. K⁺ currents and channel activity were assessed by the whole-cell voltage clamp and by either inside-out or outside-out patch clamp recordings. Cell depolarization resulted in activation of a Ca²⁺-dependent outward K⁺ current, 0.57 ± 0.13 nS/pF at −70 mV holding potential and 3.10 ± 0.15 nS/pF at 30 mV holding potential. Corresponding patch clamp measurements demonstrated a Ca²⁺-activated, voltage-dependent K⁺ channel (K_Ca) of 214 ± 3.0 pS. Scorpion venom peptides, charybdotoxin (ChTx) and iberiotoxin (IbTx), inhibited both the activated current and the K_Ca activity. In addition, on-cell patch recordings demonstrated an inwardly rectifying K⁺ channel, 21 ± 1 pS at positive transmembrane potential (V _m ) and 145 ± 13 pS at negative V _m . Glibenclamide (50 μm), Ba²⁺ (1 mm) and quinine (100 μm) each inhibited the corresponding nonactivated, basal whole-cell current. Moreover, glibenclamide inhibited K⁺ channels in inside/out patches in a dose-dependent manner, and the IC₅₀= 46 μm. The identity of this K⁺ channel with an ATP-sensitive K⁺ channel (K_ATP) was confirmed by its inhibition with ATP (2 mm) and by its activation with diazoxide (100 μm). We conclude that plasma membranes of HTB-9 cells contain the K_Ca and a lower conductance K⁺ channel with properties consistent with a sulfonylurea receptor-linked K_ATP. Received: 12 June 1997/Revised: 21 October 1997     

Molecular markers for rust and pyricularia leaf spot disease resistance in pearl millet

 Pearl millet [Pennisetum glaucum (L.) R.Br.] is a warm-season grass used for food, feed, fodder and forage, primarily in countries of Africa and India but grown around the world. The two most-destructive diseases to pearl millet in the United States are rust (caused by Puccinia substriata var. indica) and pyricularia leaf spot (caused by Pyricularia grisea). Genes for disease resistance to both pathogens have been transferred into agronomically acceptable forage and grain cultivars. A study was undertaken to identify molecular markers for three rust loci and one pyricularia resistance locus. Three segregating populations were screened for RAPDs using random decamer primers and for RFLPs using a core set of probes detecting single-copy markers on the pearl millet map. The rust resistance gene Rr ₁ from the pearl millet subspecies P. glaucum ssp. monodii was linked 8.5 cM from the RAPD OP-G8₃₅₀. The linkage of two RFLP markers, Xpsm108 (15.5 cM) and Xpsm174 (17.7 cM), placed the Rr ₁ gene on linkage-group 3 of the pearl millet map. Rust resistance genes from both Tift 89D₂ and ICMP 83506 were placed on linkage-group 4 by determining genetic linkage to the RFLP marker Xpsm716 (4.9 and 0.0 cM, respectively). Resistance in ICMP 83506 was also linked to the RFLP marker Xpsm306 (10.0 cM), while resistance in Tift 89D₂ was linked to RAPD markers OP-K19₃₅₀ (8.8 cM) and OP-O8₃₅₀ (19.6 cM). Fragments from OP-K19 and OP-O8 in the ICMP 83506 population, and Xpsm306 in the Tift 89D₂ population, were monomorphic. Only one RAPD marker (OP-D11₇₀₀, 5.6 cM) was linked to pyricularia leaf spot resistance. Attempts to detect polymorphisms with rice RFLP probes linked to rice blast resistance (Pyricularia oryzae; syn=P. grisea) were unsuccessful. Received: 19 May 1997 / Accepted: 21 October 1997     

The occurrence and identification of <Emphasis Type="Italic">Setaria italica</Emphasis> (L.) P. Beauv. (foxtail millet) grains from the Chengtoushan site (ca. 5800 cal B.P.) in central China,with reference to the domestication centre in Asia

Archaeobotanical remains of Setaria grains and chaff were found at the Chengtoushan site in south-central China (ca. 5800 cal b.p.). Grain shape was determined, using length to breadth ratios, and morphological variation in the upper lemma of modern domesticated and wild Setaria species were examined using scanning electron microscopy as a basis for identifying archaeobotanical remains. Grains of S. viridis, S. yunnanensis, and S.×pycnocoma are slender, whereas S. italica, S. italica var. germinica, S. lutescenes, S. faberi, S. glauca, S. pallidefusca and S. intermedia are round in shape. The papillae distributed on the upper lemma of S. italica are small (8–15 μm) with a non-ridged base, while other Setaria species have large papillae (15–20 μm) with a widely ridged base. The remains of the Setaria from the Neolithic layers at Chengtoushan included S. italica, based on these identification characters. These new finds of foxtail millet are the earliest discoveries from the Yangtze River basin of southern China and are also the earliest evidence for co-cultivation of foxtail millet with rice. The implications of these findings for understanding foxtail millet domestication centres are discussed.     

Age and composition of carbonate shoreface sediments, Kailua Bay, Oahu, Hawaii

The origin, age, and dynamics of carbonate sediments in Kailua Bay on Oahu, Hawaii, are described. The shoreface (from shoreline to 4 km offshore) consists of a broad (5 km²) fringing coral reef ecosystem bisected by a sinuous, shore-normal, sand-filled paleostream channel 200–300 m wide. The median grain diameter of surface sands is finest on the beach face (<0.3 mm) and increases offshore along the channel axis. Kailua sands are >90% biogenic carbonate, dominated by skeletal fragments of coralline algae (e.g. Porolithon, up to 50%) followed by the calcareous green alga Halimeda (up to 32%), coral fragments (1–24%), mollusc fragments (6–21%), and benthic foraminifera (1–10%). Sand composition and age across the shoreface are correlated to carbonate production. Corals and coralline algae, principal builders of the reef framework, are younger and more abundant in sands along the channel axis and in offshore reefal areas, while Halimeda, molluscs, and foraminifera are younger and more dominant in nearshore waters shoreward of the main region of framework building. Shoreface sediments are relatively old. Of 20 calibrated radiocarbon dates on skeletal constituents of sand, only three are younger than 500 years b.p.; six are 500–1000 years b.p.; six are 1000–2000 years b.p.; and five are 2000–5000 years b.p. Dated fine sands are older than medium to coarse sands and hence may constitute a reservoir of fossil carbonate that is distributed over the entire shoreface. Dominance of fossiliferous sand indicates long storage times for carbonate grains, which tend to decrease in size with age, such that the entire period of relative sea-level inundation (∼5000 years) is represented in the sediment. Despite an apparently healthy modern coral ecosystem, the surficial sand pool of Kailua Bay is dominated by sand reflecting an antecedent system, possibly one that existed under a +1–2 m sea-level high stand during the mid- to late Holocene. Accepted: 20 December 1999     

Host-specific Variation in Infection by Toxigenic Fungi and Contamination by Mycotoxins in Pearl Millet and Corn

Pearl millet is widely consumed in regions of Africa and Asia, and is increasingly being grown as an alternative grain in drought-prone regions of the United States. Pearl millet and corn were grown in dryland conditions at Tifton, Georgia, USA and grains were compared for pre-harvest infection by potentially toxigenic fungi and contamination by mycotoxins. Corn hybrids Agripro 9909 and Pioneer 3146, and pearl millet Tifgrain 102 were grown in 2000 and 2001; pearl millet HGM 100 was included in the test in 2001. Hybrids were sown on multiple planting dates in each year to induce variation in flowering time. Host species differed in the frequency of isolation of potentially toxigenic fungal species in both years. Across years, corn hybrids were more prone to infection by Aspergillus flavus Link (maximum isolation frequency = 8.8%) and Fusarium moniliforme Sheldon sensu lato (maximum isolation frequency = 72.8%), with corresponding greater concentrations of aflatoxins (maximum concentration = 204.9 μg kg⁻¹) and fumonisins (maximum concentration = 34,039 μg kg⁻¹). Pearl millet was more prone to infection by F. semitectum Berk. & Ravenel (maximum isolation = 74.2%) and F. chlamydosporum Wollenweb & Reinking (maximum isolation = 33.0%), and contamination by moniliformin (maximum contamination = 92.1 μg kg⁻¹). Beauvericin (maximum concentration = 414.6 μg kg⁻¹) was present in both hosts. Planting date of corn affected aflatoxin and beauvericin contamination in 2000, and fumonisin concentration in 2001. The observed differences in mycotoxin contamination of the grains, which are likely due to host-specific differences in susceptibility to pre-harvest mycoflora, may affect food safety when the crops are grown under stress conditions.