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No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces production costs relative to conventional tillage (CT). However, many producers in southern Italy are reluctant to adopt this practice because NT can have contrasting consequences on grain yield depending on weather conditions. The effect of NT and CT on continuous durum wheat ( Triticum durum Desf.) under rainfed Mediterranean conditions was studied, over a 3-year period (2000–2002) at two locations (Foggia and Vasto) in southern Italy. Yield, grain quality [thousand kernel weight (TKW), test weight (TW) and protein content (PC)] and soil water content were assessed. Higher yield was obtained with NT than CT in the first 2 years at Foggia. In contrast, mean yield and quality parameters at Vasto were similar for the two treatments, except in the third year in which CT produced more than NT (4.6 Mg ha −1 versus 2.9 Mg ha −1 ). At Foggia, TW and TKW were higher in NT than CT in all years. Highest PC was obtained under CT (19.6% and 15.5% for CT versus 14.7% and 11.4% for NT, respectively, in the growing season 2000–2001 and 2001–2002) indicating that grain was shriveled with low starch accumulation. At Foggia, where this study was part of a long-term experiment started in 1995, a strong correlation was observed between yield and rainfall during the wheat growing season. The coefficient of determination ( R 2 ) values for CT and NT were 0.69 * and 0.31 ns, respectively, and the regression straight line crossed around 300 mm of rainfall. These results indicate that NT was superior below this rainfall value, whereas more rainfall enhanced yield in CT. We conclude that NT performed better at Foggia with limited rainfall during the durum wheat growing season. The superior effect of NT in comparison to CT, was due to lower water evaporation from soil combined with enhanced soil water availability.

The plant uncoupling mitochondrial protein (PUMP) and the plant mitochondrial potassium channel (PmitoKATP) are two recently discovered energy-dissipating systems present in plant mitochondria, which may play a role as defence systems under environmental stress. To verify whether hyperosmotic stress affects the two dissipating systems in durum wheat (Triticum durum Desf.), their functioning was studied in early etiolated seedlings maintained under moderate and severe salt (NaCl) and osmotic (mannitol) stress. As measures of mitochondrial stress mitochondrial integrity, membrane potential maintenance and oxygen uptake coupled with ATP synthesis during succinate and proline oxidation were investigated. Both PUMP and PmitoKATP were activated under stress conditions. Activation was clearly evident even under moderate stress when proline oxidation was inhibited, although mitochondrial integrity and succinate oxidation were still unaffected. Under severe stress, which significantly affected all the tested indicators of mitochondrial integrity and functionality, PUMP and PmitoKATP activation was further enhanced. Interestingly, both systems were activated by reactive oxygen species and were able to control mitochondrial superoxide anion production. These results suggest that PUMP and PmitoKATP serve as early antioxidant defence systems in response to hyperosmotic stress and that they are involved in a prolonged response to stress.

Four mutants with delayed leaf senescence were selected from seed of durum wheat mutagenized with ethylmethane sulphonate. Changes in net photosynthetic rate, efficiency of photosystem II and chlorophyll concentration during the maturation and senescence of the flag leaves of both mutant and parental plants were determined under glasshouse conditions. The four mutant lines maintained photosynthetic competence for longer than the parental line and are therefore functionally 'stay green'. The mutant lines also had higher seed weights and grain yields per plant than the parental line.

During pasta making, semolina is subject to various modifications that are mainly related to oxidative activities with relative effects on some of its components. To evaluate the involvement of hydroperoxidation and bleaching of lipoxygenase (LOX) and peroxidase (POD) activities on loss of pigments and -SH groups, their behavior in semolina and during processing was analyzed. Processing was done in standard and four experimental conditions, applying chemical (pH 5.0 and 8.0) and physical (10 and 40°C) treatments, during the mixing and extrusion phases, to study their effects on components. Results pointed out that treatments principally affected hydroperoxidation and bleaching activities of LOX rather than the POD. During pasta making, enzymatic activities showed the same trend in all cultivars, and this was reproducible in all the experimental conditions. Temperature effects on preservation of components were modest, whereas pH 8.0 improved the residual pigment and -SH group content in pasta, pr...

Alfalfa ( Medicago sativa L.) is widely grown as a forage crop due to its good quality characteristics and high adaptability. However, seed yield is generally considered to be of secondary importance and is characterized by fluctuating yields with often poor seed quality. A field experiment using five alfalfa cultivars (Equipe, Iside, Lodi, Robot, Romagnola) was carried out in 1995, 1996 and 1997 at Foggia (southern Italy) to evaluate the effects of four defoliation practices (H1: crop mown during early plant growth; H2: plant desiccation by chemical agent at the end of February; H3: crop mown at early flowering; H4: never cut) and two irrigation treatments (I: irrigation applied from April to beginning of seed filling; NI: non-irrigated control) on seed yield, seed yield components and seed quality (as determined by seed germination with and without accelerated ageing (AA)). The relationships between yield components (stems per m 2 , pods per stem, seeds per pod, 1000-seed weight) were determined by path-coefficient analysis. Irrigation significantly increased seed yield; on average doubling the control yield over the three seasons. However, the potential seed yield (calculated from seed yield components) was, on average, five times the actual seed yield. The two mowing treatments produced consistently higher seed yields than either desiccated or untreated swards. Cultivar differences were evident for seed yield, with Equipe having the highest value (40% higher than the mean of the other cultivars). Irrigation improved the yield primarily because it led on average a greater than four fold increase in the density of stems (the most influential yield component). By contrast, seeds per pod and 1000-seed weight increased in the absence of irrigation. Defoliation treatments had little effect on stems per m 2 , seeds per pod and seed weight, whereas pods per stem were reduced by desiccation. Path analyses calculated across irrigation treatments and years revealed that stems per m 2 had the largest positive direct effect on alfalfa seed yield under each harvest management (path-coefficient values ≥0.89), and its indirect effects on seed yield via other traits were negligible. Seed quality, as measured by germination percentage both before and after AA, remained relatively consistent across both defoliation and irrigation treatments and cultivars, but was anomalously low in the 1997 irrigated crops. Overall, the highest seed yields were obtained under irrigated conditions when crops were mown during early growth or at early flowering. The potential seed yield of alfalfa varieties is sufficient to guarantee a profitable seed harvest. However, the harvest efficiency of the combine-harvester was low (20% of the potential seed yield); thus, more appropriate harvest techniques should be used.

Grain protein content (GPC) is an important quality factor in both durum and bread wheats. GPC is considered to be a polygenic trait influenced by environmental factors and management practice. The objectives of this study were both to compare the quantitative trait loci (QTL) for GPC in a population of 65 recombinant inbred lines of tetraploid wheats evaluated in three locations for several years (eight data sets), and to investigate the genetic relationship among GPC and grain yield. QTLs were determined based on the Messapia × dicoccoides linkage map which covers 217 linked loci on the 14 chromosomes with 42 additional loci as yet unassigned to linkage groups. The map extends to 1352 cM; the average distance between adjacent markers was 6.3 cM. Seven QTLs for GPC, located on the chromosome arms 4BS, 5AL, 6AS (two loci), 6BS, 7AS and 7BS, were detected that were significant in at least one environment at P

The quality of durum wheat cannot be simply defined since it changes depending on the worker and end-use. Here we report a description of quality aspects evaluated at different levels: by the farmer, grain dealer, seed company, milling industry, pasta industry and consumer. The transformation of durum wheat to improve the quality for traditional end-uses and for novel applications is also described.

Berseem clover (Trifolium alexandrinum L.) is an important crop in semi-arid regions; its herbage and seed yields are often reduced by water stress. Our objectives were (i) to determine the effect of water stress, applied after a conditioning period, on water relations, proline accumulation and plant dry weight, and (ii) to investigate if some physiological responses differed in varieties of berseem. Five cultivars (Axi, Bigbee, Lilibeo, Sacromonte and Saniros) were grown in a controlled environment, and subjected to four irrigation treatments (T1, T2, T3 and T4 referring to plants irrigated to field capacity every 1, 2, 3 or 4 d, respectively) during a conditioning period (12 d). T1 treatment indicated the well-watered control, whereas T2, T3 and T4 treatments represented the conditioned plants. Leaf water potential (Ψ), osmotic potential (Ψπ), relative water content (RWC), gravimetric soil water content (GSWC) and leaf proline concentration were recorded during the conditioning period and a subsequent water deficit period (3 d) applied at early flowering growth stage. The conditioned plants subjected to subsequent water deficit maintained higher values of Ψ, Ψπ, RWC and GSWC, and lower values of leaf proline concentration. Reductions in parameter values were inversely related to the water stress severity that plants had previously experienced. At the end of the experiment, T1 showed 42%, 58% and 31% lower values for Ψ, Ψπ and RWC, respectively, than those of T4. Conditioned plants were also shorter and accumulated less leaf, stem and total dry weight. The conditioning treatments did not affect the relation between Ψ and Ψπ since conditioned plants show similar values of Ψπ as the control at the same Ψ value. Thus, drought acclimation in berseem clover contributed to water stress tolerance by the maintenance of tissue hydration. The berseem cultivars examined showed differences in plant growth parameters, but they were very similar for physiological responses to water deficit. The main genetic difference was recorded for turgor maintenance capacity.

In order to gain some insights into durum wheat lipoxygenase (LOX) biochemistry and in particular in order to find out whether the antioxidants α-tocopherol and L-ascorbate can prevent the LOX-dependent semolina bleaching, which leads to a low quality of pasta product, a study of LOX activity in a crude protein extract from semolina was performed by means of spectrophotometric techniques. Measurements made of linoleate hydroperoxidation reaction (λ=234 nm) and of the coupled β-carotene bleaching reaction (λ=460 nm), demonstrated the existence of more than one enzyme exhibiting LOX activity as revealed by the different pH profiles. The linoleate hydroperoxidation reaction exhibited a sigmoidal dependence on the substrate concentration (K0·5=60±0·67 μ M ,Vmax =1·12±0·055 units/g of semolina), while β-carotene bleaching showed a hyperbolic relationship and followed the Michaelis-Menten equation (Km=3·3±0·53 μ M , Vm=0·030±0·0062 units/g). Both linoleate hydroperoxidation and β-carotene bleaching were strongly inhibited by added α-tocopherol. In both cases, the enzyme affinity for the substrate was reduced, while the Vmaxwas not affected. In particular, β-carotene bleaching was inhibited in a competitive manner (Ki=7·7±0·21 μ M ). L-ascorbate also inhibited both reactions: the Vmaxof linoleate hydroperoxidation was lowered, while theK0·5 remained unchanged; in the case of β-carotene bleaching the inhibition was uncompetitive (Ki=445±71·5 μ M ). Therefore, the use of both α-tocopherol and L-ascorbate to reduce semolina bleaching during pasta making is suggested. A purification procedure of semolina LOX is also reported, showing the existence of two isoforms.

Grain yield is a complex trait, strongly influenced by the environment: severe losses can be caused by drought, a stress common in most maize-growing areas, including temperate climatic zones. Accordingly, drought tolerance is one of the main components of yield stability, and its improvement is a major challenge to breeders. The aim of the present work was the identification, in maize genotypes adapted to temperate areas, of genomic segments responsible for the expression of drought tolerance of yield components: ear length, ear weight, kernel weight, kernel number and 50-kernel weight. A linkage analysis between the expression of these traits and molecular markers was performed on a recombinant inbred population of 142 families, obtained by repeated selfing of the F1 between lines B73 and H99. The population, genotyped at 173 loci (RFLPs, microsatellites and AFLPs), was evaluated in well-watered and water-stressed conditions. A drought tolerance index was calculated as the ratio between the mean value of the trait in the two environments. For the traits measured, a highly positive correlation was found over the two water regimes, and more than 50% of the quantitative trait loci (QTLs) detected were the same in both; moreover, the direction of the allelic contribution was always consistent, the allele increasing the trait value being mostly from line B73. Several QTLs were common to two or more traits. For the tolerance index, however, most of the QTLs were specific for a single component and different from those controlling the basic traits; in addition, a large proportion of the alleles increasing tolerance were provided by line H99. The data suggest that drought tolerance for yield components is largely associated with genetic and physiological factors independent from those determining the traits per se. The implications of these results for developing an efficient strategy of marker-assisted selection for drought tolerance are discussed.

Drought is a serious agronomic problem, and one of the most important factors contributing to crop yield loss. In maize grown in temperate areas, drought stress occurs just before and during the flowering period; consequently, tolerance to water stress in this species is largely determined by events that occur at or shortly after flowering. The purposes of our investigation were: (1) to identify the chromosomal regions where factors conferring drought tolerance for traits related to plant development and flowering are located and (2) to compare these regions with those carrying QTLs controlling these traits, in order to get indirect information on the genetic and physiological basis of maize response to water stress. To this aim, we performed a linkage analysis between the expression of male and female flowering time, anthesis-silking interval (ASI), plant height and molecular markers. The experiment was carried out under two environmental conditions, well-watered and water-stressed, on a maize population of 142 recombinant inbred lines obtained by selfing the F1 between lines B73 and H99 and genotyped by RFLP, microsatellites (SSR) and AFLP markers, for a total of 153 loci. Linkage analysis revealed that, for male flowering time and plant height, most of the QTLs detected were the same under control and stress conditions. In contrast, with respect to female flowering time and ASI diverse QTLs appeared to be expressed either under control conditions or under stress. All of the QTLs conferring tolerance to drought were located in a different chromosome position as compared to the map position of the factors controlling the trait per se. This suggests that plant tolerance, in its different components, is not attributable to the presence of favourable allelic combinations controlling the trait but is based on physiological characteristics not directly associated with the control of the character.

Test weight or bulk density in durum wheat is a physical quality characteristic considered by semolina millers. High test weight values are desirable because they positively influence market grade and price. This study reports data on kernel size features, determined on a sample size of only 25 kernels, replicated three-times, of 16 commercial durum wheat cultivars grown in two locations in southern Italy, to ascertain whether some kernel traits could be related to test weight. For each year and cultivar, the analysis of variance for all of characteristics showed that sample size effect was not significant, enabling the use such a small sample for further investigations. The kernel trait with the highest variation for year was kernel width. The absolute variation of 1994 with respect to 1993 growing season was 30.9%. While kernel weight or volume did not correlate with test weight, a negative association with kernel length (r = -0.61, P = 0.05) and perimeter (r = -0.57, P = 0.05) was found. The k...

The quantum yield of photosynthetic electron transport (ΦPSII), evaluated by means of chlorophyll (Chl) fluorescence analysis, has proven to be a useful screening test for drought tolerance in durum wheat (Triticum durum Desf.). To explore the potential of this parameter further in detecting drought-tolerant genotypes, three cereal species were studied; ΦPSII measurements were carried out under two different gas mixtures, at three points of the induction curve (to obtain the maximal ΦPSII and both the transient and steady-state actual ΦPSII), and at three different water stress levels (moderate, severe and drastic). The species investigated were durum and bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.); two cultivars per species, characterized by different levels of drought tolerance, were tested. The two gas mixtures used were normal air (21% O2, 0.035% CO2 in N2) to monitor the whole photosynthetic process under physiological conditions, and CO2 enriched-low O2 air (1% O2, 5% CO2 in N2) to monitor ΦPSII reduction under stress mainly related to Calvin cycle activity. When ΦPSII related to both assimilatory and non-assimilatory metabolism was evaluated, the cultivar differences observed under normal Air were more representative of the agronomic performance upon drought stress than under high CO2-low O2 air. Maximal ΦPSII showed no difference among either cultivars, gas mixtures or stress levels, the efficiency of excitation capture being highly resistant to drought. The ΦPSII evaluated during the transient yielded predictable values in respect of drought tolerance for durum wheat and barley cultivars, highlighting the key role of regulatory processes such as the Mehler peroxidase reaction and possibly also cyclic electron transport, in preventing overreduction under stress. The results clearly show that when Chl fluorescence analysis is used as a parameter in plant breeding, different experimental conditions should be used depending on the physiological mechanism that is bred or selected for.

In an effort to define the role of bound water in drought tolerance, relationships between the leaf segments affinity for water, leaf water status, leaf area (LA) and drought intensity were analyzed, using three durum wheat cultivars grown in a growth chamber. Previous studies indicated that Appulo and Capeiti 8 cultivars are more drought tolerant than Creso. A new simplified analysis of water sorption that consists of measuring the differences in water sorbed (DWS) by the leaf segments at two temperatures was applied to evaluate the tissue strength of water binding. The turgid weight (TW)/dry weight (DW) ratio was also determined to obtain a rough estimate of bound water. Five different levels of soil water content (SWC) were obtained by limiting irrigation water for 20 days. The TW/DW ratio was not affected by water deficit. Leaf area, water potential (Ψw) and relative water content (RWC) decreased with increasing drought intensity, but genotypic differences were not observed. At high SWC Creso showed greater DWS values than Appulo and Capeiti 8, whereas at low SWC the latter varieties had greater DWS values than Creso. The drought induced increase in DWS observed in the more drought tolerant plants was not related to greater leaf water content or growth under drought.

Many plants accumulate proline as a non-toxic and protective osmolyte under saline or dry conditions. Its accumulation is caused by both the activation of its biosynthesis and inactivation of its degradation. We report here on the alterations induced by water and salt stress in the proline metabolism and amino acid content of 5-day-old seedlings of Triticum durum cv. Simeto. Most of the amino acids showed an increase with the induction of either stress, but proline increased more markedly than did other amino acids. We also measured the activities of two enzymes, Δ 1 -pyrroline-5-carboxylate (P5C) reductase (EC 1.5.1.2) and proline dehydrogenase (EC 1.5.1.2), which are involved in proline biosynthesis and catabolism, respectively. The activity of P5C reductase was enhanced during both water and salt stress, while proline dehydrogenase was inhibited only during salt stress. The results indicate that synthesis de novo is the predominant mechanism in proline accumulation in durum wheat. Use of a cDNA clone that encodes PSC-reductase from Arabidopsis thaliana, showed no differences in the gene expression between controls and stressed plants, implying that the increase in enzyme activity is unrelated to the expression of this gene.

The aim of this study was to evaluate the agronomical performance of old unhulled wheat species (farro) in comparison with an old cultivar of durum wheat, selected for morphological and rusticity characteristics similar to farro, in a drought-flat land environment of southern Italy. The trials were carried out during the 1992/93 and 1993/94 growing seasons. Agronomical responses concerned the behaviour of the different species to weeding treatment (diclofop-methyl, 568 g a.i. ha -1 ) and to three (0 %, 50 %, 100 %) artificial weed levels with Avena fatua and Phalaris arundinacea with respect to grain yield and its components, plant morphological aspects and two qualitative characters. In all of the species the weeding treatment increased the mean values of almost all the parameters analysed except for days to head and grain protein content which remained constant. The effect of weed treatment on the characters considered was a general decrease of mean values when weed level was increased. The grain protein content showed an opposite trend. As far as the grain yield alone is concerned, yielding differential in medium and large farro decreased by 3 % whereas in small farro it increased by 4.3 % vs. durum wheat when no weeding and weeding treatments were compared. Small and large farro resulted more susceptible than medium farro and durum wheat to weed treatment. In fact, these latter showed, at the maximum weed level, the same grain yield loss as small and large farro at the 50 % weed level. Small farro was the most susceptible species, while Triticum dicoccum showed similar affinity and behaviour to durum wheat.

The unpredictability of the Mediterranean climate causes a large fluctuation in wheat yield and quality but offers the opportunity for the production of high quality wheats which are lacking in the European Union. This paper describes the effects of nitrogen fertilization rate and timing on five Triticum aestivum L. cultivars differing in bread-making quality, cultivated in six representative Italian sites (years/locations). Nitrogen was applied at each location at two rates, the first corresponding to the amount estimated to maximize grain yield, the second 30% higher. Three timings of nitrogen applications were tested including a late application at the boot stage. Bread-making quality was evaluated with the Chopin alveograph and each sample was assigned to the following qualitative classes of the Italian market: Class 1, improver wheat; Class 2, for direct bread-making; Class 3, ordinary wheat. Cultivars differed significantly in all agronomic and qualitative traits. Grain yield was highest in the northern location (7.1 t ha −1 ) and lowest in the south of the Italian peninsula (2.61 ha −1 ), while in Sicily abundant rains in both years enabled a yield of 6.41 ha −1 to be obtained. As far as bread-making quality is concerned, the greatest proportion of grain samples belonging to Class 1 was obtained from the northern location. The year of cultivation strongly affected quality, particularly with regard to gluten tenacity, in all locations, though the quality ranking of the cultivars remained substantially stable across locations. Nitrogen applications greater than those considered optimal to maximize yield, combined with a better distribution during the life cycle, significantly improved bread-making quality. It was concluded that high quality wheats can be obtained in a wide range of growing conditions in the Mediterranean climate. However the likelihood of genotype × environment interactions, statistically significant for both yield and quality, call for a more precise management of nitrogen fertilization in relation to the cultivars chosen and the climatic features of each site.

The relationships between photosynthesis and osmotic adjustment (OA) under water stress are not yet well understood. Therefore, a possible association between the quantum yield of photosynthetic electron transport at the Photosystem II level (ΦPSII) and OA was evaluated in drought-stressed durum wheat plants in this paper. Four cultivars (cvs) differing in the degree of drought resistance as estimated by the ΦPSII maintenance, were grown in a growth chamber under two different water stress cycles; in both cases two stress intensities (moderate and severe) were used. Leaf water potential (ΨW), osmotic potential at full turgor (Ψπ100), ΦPSII and the efficiency of excitation capture by open Photosystem II reaction centres (ECPSII) were determined in the different experimental conditions, both in control and stressed plants. ΦPSII and ECPSII were evaluated by in vivo chlorophyll fluorescence analysis. ΦPSII showed a significant decrease only under severe water stress and for the drought susceptible cvs; on the other hand, ECPSII showed no change under the different water stress conditions. The percent decrease of ΦPSII under water deficit was confirmed to be a good indicator of drought resistance in durum wheat. OA was estimated as the difference in the Ψπ100 between leaves from water-stressed and well-watered plants. No relationship between the maintenance of the ΦPSII and OA under water deficit was observed in the adopted experimental conditions; this result is discussed in the light of the contrasting evidence in the literature.

The influence of cutting applied at four stages of plant growth on dry matter, crude protein, total available carbohydrates and reducing sugar partitioning was examined in six genotypes of berseem (Trifolium alexandrinum L.). The research was conducted in Foggia (Italy) during 1990 and 1991 in a glasshouse with controlled water application. The plants were grown in a plastic-lined, PVC cylinder. At each cut, dry matter and chemical components were evaluated in leaf, stem and root fractions; at the end of the biological cycle, seed yield was recorded. Plants showed similar dry matter partitioning between leaves and stems at the eighth internode stage. The crude protein concentration was highest in leaf fractions, reaching the maximum value (31%) at an early stage of growth (fourth internode stage). The maximum value of total available carbohydrates was obtained in the stems at the early flowering stage (11 %), whereas reducing sugars almost always showed higher concentrations in the leaves (4 %). As for forage and seed yields, the developmental stage at cutting had a great influence on dry matter and chemical component partitioning among the different organs. Genotypic differences were observed for dry matter partitioning in leaves and stems in all developmental stages, but diversity in chemical component content was more evident in the roots.

SUMMARYThe chlorophyll fluorescence parameters ΔF/Fm′ and Fv′/Fm′, related respectively to the quantum yield of photosynthetic electron transport and to the efficiency of excitation capture by the open centres of photosystem II, have been evaluated as possible indicators of drought tolerance in durum wheat. ΔF/Fm′ and Fv′/Fm′ measurements were carried out on excised leaves, both control and dehydrated, of 25 cultivars. ΔF/Fm′ and Fv′/Fm′ values were obtained at two times after the start of fluorescence measurement: at 14 s, i.e. during the induction curve (ΔF/Fm′14s and Fv′/Fm′14s) and at 200s, i.e. at steady state fluorescence (ΔF/Fm′200s and Fv′/Fm′200s).In dehydrated leaves a mean significant decrease of 20% (P < 0·001) was observed in ΔF/Fm′14s values. In contrast, no great differences were observed between control and dehydrated leaves with regard to ΔF/Fm′200s, Fv′/Fm′14s and Fv′/Fm′200s.The percentage decrease of ΔF/Fm′14s after dehydration was correlated with the drought susceptibility index (DSI) of the cultivars, evaluated on a yield basis and a significant correlation (r = 0·72, P < 0·001) was found.

Summary The relationship of the expression levels of drought — ( AF93 — Grossi et al., 1992) and ABA-regulated genes ( Dhn1 — Close et al., 1989), water potential and ABA content was analyzed in durum wheat at the grain-filling stage. The moisture-stressed plants exhibited a marked reduction of water potential, a rise in ABA content and induction of mRNAs homologous to AF93 ; no mRNAs homologous to Dhn1 were found.

Triticum monococcum ssp. monococcum (einkorn), a widely cultivated crop in the Neolithic age, is reconsidered in modern agriculture because of the rising demand for high quality, low input cereals. Yield and yield related traits of Triticum monococcum ssp. monococcum (einkorn) were measured by growing twenty-one lines in Cologne (Germany), Milano, Ascoli Piceno and Foggia (Italy). The effects of six different seeding rates (ranging from 100 to 600 kernels m−2) and three different nitrogen levels (0, 80 and 120 kg ha−2) were tested at three Italian locations (Milano, Chieuti and Foggia). The gross grain yield (i.e., the yield of the grain with adhering glumes) was influenced by the environment, with a maximum at Cologne (4.5 t ha−2) and a minimum at Foggia (0.84 t ha−2). The three nitrogen levels did not influence grain yield or plant height. These two traits and the heading time were significantly affected by the seeding rate. The maximum gross grain yield was obtained with a seeding rate of 300 kernels m−2. With the exception of the total biomass and the number of spikes m−2 , all other yield related traits varied significantly among the einkorn lines. In the Southern environments the long life cycle of einkorn wheat appears to be a yield-limiting factor. The observed genetic differences for important traits like earliness in this limited sample of einkorn lines, indicate that breeding programs could generate lines being better adapted to modern farming.

Variations in water binding strength, water relations and the accumulation of solutes during water stress of three durum wheat (Triticum durum Desf.) cultivars are reported and discussed. Water binding strength was determined by constructing adsorption isotherms at 5 and 20°C and by calculating the differential enthalpy (ΔH) after van't Hoff. Reducing sugars, proline, K+ and Cl− were the major contributors to osmotic adjustment. Solutes, such as quaternary ammonium compounds, and non-reducing sugars contributed to osmotic potential at full turgor, but did not increase in proportion to water stress. Genotypic differences have been observed for K+ accumulation capability, the water-stressed leaves of cv. Capeiti 8 showing the largest increase. The same cultivar demonstrated the most negative ΔH values, indicative of strongly bound water, and the highest integrated enthalpy (ΔHinf) values for leaf moisture below 0.1 g H2O per g dry weight, i.e. in the isotherm region where water was presumably chemisorbed to the charged groups of macromolecules. The accumulation of ions (Cl−, K+) and proline was concurrent with an increase in the binding-strength of tightly and weakly bound water, respectively.

SUMMARYThe aim of this study was to identify a fluorescence parameter whose estimate could be used reliably for a drought tolerance test in durum wheat (Triticum durum). Twenty-five cultivars were grown in a glasshouse over two seasons (1987/88 and 1988/89) at Foggia, Southern Italy. Photochemical and non-photochemical quenching (qQ and qE), the half time of fluorescence decay (tP½) and the initial slope of fluorescence decay (ISPS) were measured on control and dehydrated pre-darkened excised leaves; qQ and qE were measured twice: first at 14 s after actinic illumination and second at the steady state.No great difference in qQ and qE was apparent between control and dehydrated leaves at the steady state; however, at 14 s after illumination there was a decrease in qQ and in ISPS and an increase in tP½ in dehydrated leaves. The predictive capability of fluorescence parameters was assessed by comparison with a yield-based drought susceptibility index (DSI). The percentage decrease in qQ at 14 s showed the highest correlation with DSI (r = 0·75, significant at P < 0·001), so it may be considered a good indicator of drought tolerance in durum wheat. Results obtained at different developmental stages with different fluorescence levels (Fo, P and Fm) and parameters (qQ, qE and tP½) indicated that for maximum reliability the test must be applied at the vegetative phase.

Among the cultivars of bread wheat, durum wheat and barley grown in the South of Italy, genetic variation for adaptation to the high temperature and drought stress conditions typical of the Mediterranean environment has been found.

Mapping quantitative trait loci (QTLs) responsible for malting quality traits in barley populations has been the main genetic approach to malting quality breeding. A ‘winter × spring’ doubled haploid barley population ‘Nure’ × ‘Tremois’, where such traits were segregating, has been recently developed. Our objective was to map QTLs for malting quality from 2 years of trials in two contrasting locations. QTLs were found on six chromosomes, with a main cluster on chromosome 1H. For wort viscosity and malt extract, favourable alleles at two loci on chromosome 5H were carried by the winter feeding parent ‘Nure’. Doubled-haploids with higher quality than the spring malting cultivar ‘Tremois’ showed either a facultative or a winter growth habit and a level of frost tolerance comparable with that of the winter tolerant parent ‘Nure’. Markers and QTLs of quality traits were further validated on a separate set of DH lines, coming from the same cross, by means of marker-assisted selection. This showed that, at least in the present cross combination, positive contributions to malting quality can be found in winter feed barley.

The regulation of protein expression and activity has been for long time considered only in terms of transcription/translation efficiency. In the last years, the discovery of post-transcriptional and post-translational regulation mechanisms pointed out that the key factor in determining transcript/protein amount is the synthesis/degradation ratio, together with post-translational modifications of proteins. Polyubiquitinaytion marks target proteins directed to degradation mediated by 26S-proteasome. Recent functional genomics studies pointed out that about 5% of Arabidopsis genome codes for proteins of ubiquitination pathway. The most of them (more than one thousand genes) correspond to E3 ubiquitin ligases that specifically recognise target proteins. The huge size of this gene family, whose members are involved in regulation of a number of biological processes including hormonal control of vegetative growth, plant reproduction, light response, biotic and abiotic stress tolerance and DNA repair, indicates a major role for protein degradation in control of plant life.

Bound water has been studied intensively in relation to abiotic stress tolerance, but investigations of its role as a component of drought resistance in crop plants have been hampered by lack of rapid, inexpensive, and reliable methods capable of processing large populations in a short time. We investigated the possibility of estimating thermodynamic properties of strongly bound water in wheat leaves (Triticum durum Desf.) using a simplified analysis of water sorption, which made use of 39 paired isotherm curves constructed at 5 and 20°C, and thermodynamic parameters derived from them. Tissue affinity for strongly bound water (expressed as average differential enthalpy = ΔH) was compared with measurements of the difference in water sorbed (DWS) by the leaves at 5 and 20°C at relative humidities of 7, 11, 33, and 43%. Measurement of DWS at 33% relative humidity gave the best estimate of ΔH, and therefore constituted a reliable, inexpensive, simplified method for the evaluation of tissue affinity for strongly bound water.

The sustained increase of users and the request for advanced multimedia services are amongst the key motivations for designing new high-capacity cellular telecommunication systems. The proposals that are being pursued by several studies and field implementations consider hierarchical architectures and dynamic resource allocation. A hierarchical cellular communication network is analyzed, taking user mobility into account and exploiting dynamic channel-allocation schemes. In particular, a finite number of users has been considered, moving at different speeds in a geographical region covered by a finite number of cells structured in two hierarchical levels: micro- and macrocells. For such a system, mobility and traffic models have been developed, both based on queueing networks analyzing maximum packing (MP), a dynamic channel-allocation scheme. The obtained results, validated by simulation experiments, allow the evaluation of main system-performance parameters in terms of new-call and handoff blocking probabilities, and forced-termination probability as a function of load and system parameters.

Grain protein content (GPC) is an important quality factor in both durum and bread wheats. GPC is considered to be a polygenic trait influenced by environmental factors and management practice. The objectives of this study were both to compare the quantitative trait loci (QTL) for GPC in a population of 65 recombinant inbred lines of tetraploid wheats evaluated in three locations for several years (eight data sets), and to investigate the genetic relationship among GPC and grain yield. QTLs were determined based on the Messapia x dicoccoides linkage map which covers 217 linked loci on the 14 chromosomes with 42 additional loci as yet unassigned to linkage groups. The map extends to 1352 cM; the average distance between adjacent markers was 6.3 cM. Seven QTLs for GPC, located on the chromosome arms 4BS, 5AL, 6AS (two loci), 6BS, 7AS and 7BS, were detected that were significant in at least one environment at P0.001 or in at least two environments at P0.01. One QTL was significant in all but one environment, two were significant in four or five environments, and four were significant in two out of eight environments. Six out of seven protein content QTLs had pleiotropic effects or were associated to QTLs for grain yield and explained the negative correlation among GPC and yield components. The present results support the concept that studies conducted in a single environment are likely to underestimate the number of QTLs that can influence a trait and that the phenotypic data for a quantitative trait should be collected over a range of locations to identify putative QTLs and determine their phenotypic effects.

The characterization of the promoter of a wheat (Triticum aestivum) cv. Cheyenne high molecular weight glutenin subunit (HMW subunit) gene, Glu-1D-1 is reported. The nucleotide sequence of the promoter from position -1191 to -650 with respect to the transcription start site was determined, to add to that already determined. Analysis of this region of the promoter revealed the presence of an additional copy of part of the primary enhancer sequence and sequences related to regulatory elements present in other wheat seed protein genes. A chimaeric gene was constructed comprising the 5' flanking region of the Glu-1D-1 gene from position -1191 to +58, the coding region of the UID:A (Gus) gene, and the nopaline synthase (Nos) gene terminator. This chimaeric gene was introduced into wheat (Triticum durum cv. Ofanto) by particle bombardment of inflorescence explants. Two independent transgenic lines were produced, and both showed expression of the Gus gene specifically in the endosperm during mid-development (first detected 10-12 d after anthesis). Histochemical analysis of homozygous T(2) seed confirmed this pattern of expression, and showed that expression was initiated first in the central lobes of the starchy endosperm, and then spread throughout the endosperm tissue, while no expression was detected in the aleurone layer. Native HMW subunit protein was detectable by Western analysis 12-14 d after anthesis, consistent with concurrent onset of activity of the native and introduced HMW subunit gene promoters.

Summary Recent works on hexaploid wheat and barley have demonstrated that the cephalosporin antibiotic, cefotaxime, stimulates callus growth, embryogenesis, and plant regeneration (Mathias and Boyd, 1986; Mathias and Mukasa, 1987). Cefotaxime was added in various concentrations to the callus culture medium of two varieties of durum wheat, cv. Ofanto and Creso, characterized by different regenerative capabilities, both under propagative and regenerative conditions. Results obtained showed that cefotaxime did not influence callus induction frequency and the number of established regenerable cell lines, as callus culture. Conversely, cefotaxime strongly promoted plant regeneration in both genotypes tested. In particular, the variety Creso, characterized by a low number of regenerated plantlets obtained per gram fresh weight callus, enhanced regeneration up to 17-fold the value obtained in non-treated calli. Intact active cefotaxime was needed for the maximum effect on the cultures, because autoclaved antibiotic did not show any consistent effect. These observations suggest that cefotaxime can be utilized for improving non-responding genotypes in cereal tissue culture studies.

The maize locus, Opaque-2, controls the expression in developing endosperm of structural genes encoding a family of storage proteins, the 22 kd zeins, and an abundant albumin, termed b-32. It is shown that the promoter of the b-32 gene is activated in vivo in the presence of the O2 gene product and that the information necessary for this activation resides in a 440 bp DNA fragment containing five O2 binding sites (GATGAPyPuTGPu). Two of these sites are embedded in copies of the 'endosperm box', a motif thought to be involved in endosperm-specific expression, which is also represented in 22 kd zein promoters. The O2 protein is also shown to be capable of binding in vitro and activating in vivo, its own promoter.

The synthesis and deposition of seed storage proteins in maize are affected by several dominant and recessive mutants. The effect of three independent mutations, floury-2 (fl2), Defective endosperm-B30 (De-B30), and Mucronate (Mc), that reduce zein level in the endosperm were investigated. These mutations also control the level of b-70, a polypeptide bound to protein bodies, which is separable into the two isoforms b-70I and b-70II by two-dimensional gel electrophoresis. Both isoforms are overexpressed 10-fold in fl2; however, only b-70I is present in De-B30 and Mc, which contain an amount of total b-70 isoforms fivefold higher than in the wild type. Both b-70I and b-70II resemble heat shock protein (HSP70) in that they bind ATP, cross-react with anti-HSP antibodies, and have N-terminal sequence homology to HSP70. All maize protein body-located b-70 characteristics are typical of those of chaperone-like HSPs. A third protein, b-70III, similar in size to but slightly more acidic than b-70I and b-70II, also binds ATP and reacts with the same antibody, providing evidence for the presence in endosperm extracts of a cytosolic chaperone-like protein. The level of b-70III was not altered by the mutations studied. The results suggested that the repression effect of the three mutations on zein accumulation may be mediated by the alteration of a zein transport or zein assembly process involving b-70I and b-70II.

As derived from a cDNA clone, the structure of the b-32 protein of Zea mays, a putative regulatory factor of zein expression, has a central acidic region separated by two domains covered by secondary structure motifs. In this work, three b-32 genomic clones were selected from two genomic libraries obtained from the maize inbred lines W64A and A69Y. The nucleotide sequences of the complete coding region of each b-32 gene, as well as long stretches of their 5' and 3' flanking regions, were determined. Introns are not present in the b-32 genomic sequences. Minor variations among the three genes and an earlier reported b-32 cDNA indicates that they constitute a gene family showing a characteristic polymorphism. Such a polymorphism is highly evident in large segments of the upstream regulatory sequences. Interestingly, when compared with cDNA (W64A) or with gene b-32.120 (W64A), the genes b-32.129 (W64A) and b-32.152 (A69Y) show three jumps of the reading frame in the central part of the coding region, resulting in a completely different sequence of the b-32 protein central domain. In all cases, variations in the N- and C-terminal domains account only for microheterogeneity.

The deposition of zein protein in maize endosperm is under the control of several regulatory loci. The isolation of DNA sequences corresponding to Opaque-2 (O2), one of such loci, is described in this paper. The mutable allele, o2-m5 was first induced moving the Ac transposable element present at the wx-m7 allele to the O2 locus. Genetic data suggest that a functional Ac element is responsible for the observed somatic mutability of o2-m5. The isolation of genomic clones containing flanking sequences corresponding to the O2 gene was possible by screening an o2-m5 genomic libary with a probe corresponding to internal Ac sequences usually absent in the defective element Ds. Out of 27 clones isolated with homology to the central part of Ac element, only clones 6IP and 21IP generated a 2.5 kb internal fragment size of an active Ac element when digested with PvuII restriction enzyme. A sequence representing a XhoI fragment of 0.9 kb lying, in the 6IP clone, adjacent to the Ac elements, was subcloned and utilized to prove that it corresponded to a part of the O2 gene. To obtain this information we made use of: (1) DNAs from several reversions originating from the unstable (o2mk-(r) allele, which, when digested with SstI, showed a correct 3.4 kb fragment typical of non-inserted alleles of the O2 locus; and (2) recessive alleles of the O2 locus which were devoid of a 2.0 kb mRNA, present on the contrary in the wild type and in other zein regulating mutants different from O2.