Early production of table olives at a mid-7th millennium BP submerged site off the Carmel coast (Israel).

We present here the earliest evidence for large-scale table olive production from the mid-7th millennium BP inundated site of Hishuley Carmel on the northern Mediterranean coast of Israel. Olive pit size and fragmentation patterns, pollen as well as the architecture of installations associated with pits from this site, were compared to finds from the nearby and slightly earlier submerged Kfar Samir site. Results indicate that at Kfar Samir olive oil was extracted, while at Hishuley Carmel the data showed that large quantities of table olives, the oldest reported to date, were prepared. This process was most probably facilitated by the site's proximity to the Mediterranean Sea, which served as a source of both sea water and salt required for debittering/pickling/salting the fruit, as experimentally demonstrated in this study. Comparison of pit morphometry from modern cultivars, wild-growing trees and the archaeological sites, intimates that in pit morphology the ancient pits resemble wild olives, but we cannot totally exclude the possibility that they derive from early cultivated trees. Our findings demonstrate that in this region, olive oil production may have predated table olive preparation, with each development serving as a milestone in the early exploitation of the olive.

Experimental growing of wild pea in Israel and its bearing on Near Eastern plant domestication.

BACKGROUND AND AIMS: The wild progenitors of the Near Eastern legumes have low germination rates mediated by hardseededness. Hence it was argued that cultivation of these wild legumes would probably result in no yield gain. Based on the meagre natural yield of wild lentil and its poor germination, it was suggested that wild Near Eastern grain legumes were unlikely to have been adopted for cultivation unless freely germinating types were available for the incipient farmers. Unlike wild cereals, data from experimental cultivation of wild legumes are lacking. METHODS: Replicated nurseries of wild pea (Pisum elatius, P. humile and P. fulvum) were sown during 2007-2010 in the Mediterranean district of Israel. To assess the effect of hardseededness on the yield potential, seeds of the wild species were either subjected to scarification (to ensure germination) or left intact, and compared with domesticated controls. KEY RESULTS: Sowing intact wild pea seeds mostly resulted in net yield loss due to poor establishment caused by wild-type low germination rates, while ensuring crop establishment by scarification resulted in net, although modest, yield gain, despite considerable losses due to pod dehiscence. Harvest efficiency of the wild pea plots was significantly higher (2-5 kg seeds h(-1)) compared with foraging efficiency in wild pea populations (ranging from a few grams to 0·6 kg h(-1)). CONCLUSIONS: Germination and yield data from 'cultivation' of wild pea suggest that Near Eastern legumes are unlikely to have been domesticated via a protracted process. Put differently, the agronomic implications of the hardseededness of wild legumes are incompatible with a millennia-long scenario of unconscious selection processes leading to 'full' domestication. This is because net yield loss in cultivation attempts is most likely to have resulted in abandonment of the respective species within a short time frame, rather than perpetual unprofitable cultivation for several centuries or millennia.

Evidence of polar auxin flow in 375 million-year-old fossil wood.

In living woody seed plants (conifers and dicotyledons), when various obstacles such as buds and branches disrupt the axial polar auxin flow, auxin whirlpools are formed that induce the differentiation of circular tracheary elements in the secondary xylem. Identical circular patterns also occur at the same positions in the wood of the 375 million-year-old Upper Devonian fossil progymnosperm Archaeopteris. We propose that this is the earliest clear fossil evidence of polar auxin flow. Such spiral patterns do not occur in the primary xylem of the ca. 390-385 million-year-old Lower Devonian fossil land plants, fossil progymnosperms, Psilotum nudum, living ferns, and current seed plants that we examined. This discovery reveals an exciting potential for plant fossils to provide structural evidence of evolutionarily diagnostic physiological and developmental mechanisms and for the use of a combination of fossil evidence and developmental biology to characterize evolutionary patterns in terms of genetic changes in growth regulation.

Vernalization response of wild chickpea.

• Response to low temperature during early growth in cultivated chickpea (Cicer arietinum) and its wild progenitor C. reticulatum was investigated to clarify the evolutionary processes under domestication in this crop. • Parental lines and their F2 and F3 progeny were exposed to cold treatment (4°C) for 30°d after seed imbibition and compared with controls. • Cold treatment caused a 19-d advance in flowering time in wild chickpea, but only a 3-d advance in cultivated chickpea. It also promoted apical dominance of the main stem of the wild chickpea, whereas apical dominance was constitutive in the cultivated type. F3 progeny showed significant genetic variation affecting the response of flowering time to low temperature. We suggest that selection against alleles conferring vernalization requirements was a major step in the evolution of cultivated chickpea. The reduced low-temperature response was fundamental both for the ancient conversion of chickpea from an autumn- to a spring-sown crop ('summer crop') in west Asia, and for its spread into the lower-latitude regions of India and east Africa. • Attempts to improve yield and/or resistance to biotic and abiotic stresses through introgression with wild chickpea species carry the risk of reintroducing vernalization sensitive alleles into the cultigen.

Aposematic (warning) coloration associated with thorns in higher plants.

Aposematic coloration, a well-known phenomenon in animals, has been given little attention in plants. Here I discuss two types of conspicuousness of thorns which are typical of many plant species: (1) colorful thorns, and (2) white spots, or white and colorful stripes, associated with thorns in leaves and stems. Both types of aposematic coloration predominate the spine system of taxa rich with spiny species-Cacti, the genera Agave, Aloe and Euphorbia. The phenomena have been recorded here in over a thousand species originating in several continents of both the Old and New World. I propose that this is a case of vegetal aposematic coloration analogous to such coloration of poisonous animals, and which communicates between plants and herbivores.

Clausa, a tomato mutant with a wide range of phenotypic perturbations, displays a cell type-dependent expression of the homeobox gene LeT6/TKn2.

Class I knox genes play an important role in shoot meristem function and are thus involved in the ordered development of stems, leaves, and reproductive organs. To elucidate the mechanism underlying the expression pattern of these homeobox genes, we studied a spontaneous tomato (Lycopersicon esculentum) mutant that phenotypically resembles, though is more extreme than, transgenic plants misexpressing class I knox genes. This mutant was found to carry a recessive allele, denoted clausa:shootyleaf (clau:shl)-a newly identified allele of clausa. Mutant plants exhibited abnormal leaf and flower morphology, epiphyllus inflorescences, fusion of organs, calyx asymmetry, and navel-like fruits. Analysis by scanning electron microscopy revealed that such fruits carried ectopic ovules, various vegetative primordia, as well as "forests" of stalked glandular trichomes. In situ RNA hybridization showed a peculiar expression pattern of the class I knox gene LeT6/TKn2; expression was restricted to the vascular system and palisade layer of mature leaves and to the inner part of ovules integuments. We conclude that CLAUSA regulates various aspects of tomato plant development, at least partly, by rendering the LeT6/TKn2 gene silent in specific tissues during development. Considering the expression pattern of LeT6/TKn2 in the clausa mutant, we suggest that the control over a given homeobox gene is maintained by several different regulatory mechanisms, in a cell type-dependent manner.

Developmentally regulated organ-, tissue-, and cell-specific expression of calmodulin genes in common wheat.

Recently, we reported on the characterization of the calmodulin (CaM) gene family in wheat [44]. We classified wheat CaM genes into four subfamilies (SFs) designated SF-1 to SF-4, each representing a series of homoeoallelic loci on the homoeologous chromosomes of the three genomes of common wheat. Here we studied the expression of these wheat CaM genes in the course of wheat development. Northern blot analysis using SF-specific probes revealed differences in SF expression levels in different organs and stages of development. Subsequently, cell-specific expression of CaM SFs was investigated by in situ RNA hybridization. In developing seeds, all CaM SFs showed highest expression in the embryo and less in the aleurone and in the starchy endosperm. In primary roots, all four CaM SFs were expressed in the root cap, meristematic regions and in differentiating cells. During development of the roots, expression gradually decreased. The wheat glutenin gene, which was used as a control throughout our experiments, was found to be expressed in the starchy endosperm but not in the aleurone, embryos or vegetative tissues. In stems, at advanced stages of growth, differences in cell-specific expression of CaM SFs were found. For example, SF-2 was highly expressed in differentiating phloem fibers. Thus, CaM genes in common wheat exhibit a developmentally regulated organ-, tissue-, cell- and SF-specific expression patterns.

Expression of an Aspartate Kinase Homoserine Dehydrogenase Gene Is Subject to Specific Spatial and Temporal Regulation in Vegetative Tissues, Flowers, and Developing Seeds.

Although the regulation of amino acid synthesis has been studied extensively at the biochemical level, it is still not known how genes encoding amino acid biosynthesis enzymes are regulated during plant development. In the present report, we have used the [beta]-glucuronidase (GUS) reporter gene to study the regulation of expression of an Arabidopsis thaliana aspartate kinase-homoserine dehydrogenase (AK/HSD) gene in transgenic tobacco plants. The polypeptide encoded by the AK/HSD gene comprises two linked key enzymes in the biosynthesis of aspartate-family amino acids. AK/HSD-GUS gene expression was highly stimulated in apical and lateral meristems, lateral buds, young leaves, trichomes, vascular and cortical tissues of growing stems, tapetum and other tissues of anthers, pollen grains, various parts of the developing gynoecium, developing seeds, and, in some transgenic plants, also in stem and leaf epidermal trichomes. AK/HSD-GUS gene expression gradually dimished upon maturation of leaves, stems, floral tissues, and embryos. GUS expression was relatively low in roots. During seed development, expression of the AK/HSD gene in the embryo was coordinated with the initiation and onset of storage protein synthesis, whereas in the endosperm it was coordinated with the onset of seed desiccation. Upon germination, AK/HSD-GUS gene expression in the hypocotyl and the cotyledons was significantly affected by light. The expression pattern of the A. thaliana AK/HSD-GUS reporter gene positively correlated with the levels of aspartate-family amino acids and was also very similar to the expression pattern of the endogenous tobacco AK/HSD mRNA as determined by in situ hybridization.

Calmodulin binding to glutamate decarboxylase is required for regulation of glutamate and GABA metabolism and normal development in plants.

Glutamate decarboxylase (GAD) catalyzes the decarboxylation of glutamate to CO2 and gamma-aminobutyrate (GABA). GAD is ubiquitous in prokaryotes and eukaryotes, but only plant GAD has been shown to bind calmodulin (CaM). Here, we assess the role of the GAD CaM-binding domain in vivo. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain (GADdeltaC plants) exhibit severe morphological abnormalities, such as short stems, in which cortex parenchyma cells fail to elongate, associated with extremely high GABA and low glutamate levels. The morphology of transgenic plants expressing the full-length GAD (GAD plants) is indistinguishable from that of wild-type (WT) plants. In WT and GAD plant extracts, GAD activity is inhibited by EGTA and by the CaM antagonist trifluoperazine, and is associated with a CaM-containing protein complex of approximately 500 kDa. In contrast, GADdeltaC plants lack normal GAD complexes, and GAD activity in their extracts is not affected by EGTA and trifluoperazine. We conclude that CaM binding to GAD is essential for the regulation of GABA and glutamate metabolism, and that regulation of GAD activity is necessary for normal plant development. This study is the first to demonstrate an in vivo function for CaM binding to a target protein in plants.

A basic-type PR-1 promoter directs ethylene responsiveness, vascular and abscission zone-specific expression.

Pathogenesis-related (PR) proteins form a heterogeneous group of host-encoded, low-molecular-mass proteins that are secreted through the exocytic pathway. They are synthesized by the plant in response to various stimuli, including pathogen attack or exposure to certain chemicals. The PRB-1b gene of Nicotiana tabacum codes for a basic-type PR-1 protein whose transcription is regulated by ethylene. A minimal ethylene-responsive promoter element was defined by deletion analysis in transgenic tobacco plants. Promoter sequences containing 213 bp or more were sufficient to enhance a 20-fold increase of beta-glucuronidase reporter gene expression in transgenic tobacco leaves exposed to 20 microliters l-1 of ethylene, while 67 bp were not sufficient to trigger ethylene responsiveness. All the constructs that retained ethylene inducibility exhibited phloem-specific activity, which was constitutive in petiole and pedicel abscission zones. This functional study was correlated to an in vitro screening of the major nuclear proteins' binding sites present on the promoter. Gel-shift analysis using nuclear extracts from ethylene-treated and non-treated plants revealed five sequence-specific protein-DNA complexes on promoter sequences spanning -863 to -142 bp. Constitutive expression of the basic-type PR-1 genes at the leaf and petiole or flower and pedicel interfaces may represent pre-emption of plant defenses against potential pathogens, suggesting a functional similarity to pathogen-induced expression in the leaf.