Mapping QTLs for Yield Stability in Durum Wheat Grown under Different Water Regimes

Among the most important Mediterranean annual crops, durum wheat is widely grown in drought-prone areas. Therefore, improving water-use efficiency （WUE） of durum wheat represents a major breeding goal. IDu-WUE （Improving Durum wheat for Water Use Efficiency and yield stability through physiological and molecular approaches） is a collaborative project among public and private research centres in Italy, Spain and WANA （West Asia and North Africa） countries （Morocco, Tunisia, Syria and Lebanon） funded by the European Union aimed at investigating the genetic variation for WUE and yield stability in durum wheat grown in Mediterranean droughtprone areas. During the first year of the project, a number of morpho-physiological traits （e.g. early vigour, flowering time, leaf rolling, number of fertile tillers, etc.）, WUE, WUE-related traits （e.g. carbon isotope discrimination, canopy temperature, chlorophyll fluorescence, etc.）, yield and its components have been investigated in a RIL population （249 lines） and a collection of ca. 190 durum wheat accessions characterized by a high level of linkage disequilibrium （Maccaferri et al., 2005）,     

Effect of Staphylococcus aureus and Streptococcus uberis on apoptosis of bovine mammary gland lymphocytes

The aim of this study was to determine whether lymphocyte apoptosis is modulated by infections caused by Staphylococcus aureus and Streptococcus uberis. Samples of cell populations were obtained by lavage of the mammary glands at 4 intervals (24, 48, 72 and 168 h) following infection. The percentage of apoptotic lymphocytes peaked at 168 h after challenge with S. aureus or S. uberis. Subsequent experiments focused on in vitro cultivation of mammary gland lymphocytes with S. aureus and S. uberis. These experiments showed a lower percentage of apoptotic lymphocytes following 3 h of cultivating cells with bacteria than after cultivation without bacteria. The results demonstrate that during both experimental infection of bovine mammary glands with S. aureus or S. uberis and during in vitro cultivation of lymphocytes with S. aureus or S. uberis, apoptosis of lymphocytes is delayed.     

Responses of Batis maritima plants challenged with up to two‐fold seawater NaCl salinity

Batis maritima is a promising halophyte for sand‐dune stabilization and saline‐soil reclamation. This species has also applications in herbal medicine and as an oilseed crop. Here, we address the plant response to salinity reaching up to two‐fold seawater concentration (0–1000 mM NaCl), with a particular emphasis on growth, water status, mineral nutrition, proline content, and photosystem II integrity. Plant biomass production was maximal at 200 mM NaCl, and the plants survived even when challenged with 1000 mM NaCl. Plant water status was not impaired by the high accumulation of sodium in shoots, suggesting that Na⁺ compartmentalization efficiently took place in vacuoles. Concentrations of Mg²⁺ and K⁺ in shoots were markedly lower in salt‐treated plants, while that of Ca²⁺ was less affected. Soluble‐sugar and chlorophyll concentrations were hardly affected by salinity, whereas proline concentration increased significantly in shoots of salt‐treated plants. Maximum quantum efficiency (F_v/F_m), quantum yield of PSII (Φ_PSII), and electron‐transport rate (ETR) were maximal at 200–300 mM NaCl. Both nonphotochemical quenching (NPQ) and photochemical quenching (qP) were salt‐independent. Interestingly, transferring the plants previously challenged with supraoptimal salinities (400–1000 mM NaCl) to the optimal salinity (200 mM NaCl) substantially restored their growth activity. Altogether, our results indicate that B. maritima is an obligate halophyte, requiring high salt concentrations for optimal growth, and surviving long‐term extreme salinity. Such a performance could be ascribed to the plant capability to use sodium for osmotic adjustment, selective absorption of K⁺ over Na⁺ in concomitance with the stability of PSII functioning, and the absence of photosynthetic pigment degradation.     

Two complementary recessive genes conferring resistance to Cucurbit Aphid Borne Yellows Luteovirus in an Indian melon line (cucumis melo L.)

The genetic control of resistance to cucurbit aphid-borne yellows luteovirus (CABYV) in Cucumis melo L. was studied in three progenies obtained from the cross between a resistant Indian line, PI 124112, and a susceptible cultivar of Charentais type, Védrantais. An F2 progeny and recombinant inbred lines were screened respectively in 1993 and 1995 under natural infection conditions in open field at Montfavet, France whereas the back cross (PI 124112 × F1) was inoculated by viruliferous Myzus persicae in controlled conditions. ELISA was used for assessing degree of virus multiplication in the plants resistance. In the three trials performed, segregation analysis were consistent with the hypothesis that the resistance to CABYV in PI 124112 is conferred by two independent complementary recessive genes, for which the symbols cab-1 and cab-2T are proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Combined effects of salinity and phosphorus availability on growth,gas exchange,and nutrient status of Catapodium rigidum

The combined effects of NaCl-salinity and phosphorus deficiency on biomass production, nutritional status, and photosynthetic activity were studied in Catapodium rigidum: an annual Poacea with fodder potential. Plants were grown in hydroponic conditions for 55 days under two phosphorus (P) supply: 5 (low) or 180?µmol KH₂PO₄ (sufficient), in the absence or presence of 100?mM NaCl. Obtained results demonstrated that both salinity and P deficiency treatments applied separately reduced substantially plant growth and CO₂ assimilation rate with a more marked impact of salt stress. Salinity has no substantial effect on both shoot P concentrations and phosphorus acquisition efficiency independently of P availability. The highest decrease in plant growth (?91%) was observed in plants simultaneously submitted to both stresses suggesting an additive effect of the two stresses and that P deficiency increased the susceptibility of C. rigidum to salinity. This may be linked to a significant decrease in potassium acquisition (?95%), K/Na selectivity ratio (?73%), stomatal conductance (?66%), CO₂ assimilation rate (?64%), and shoot water content (66%). Furthermore, plants cultivated under combined salinity and sufficient P supply displayed higher stomatal conductance, CO₂ assimilation rate, K/Na selectivity ratio, and plant growth than plants cultivated under combined effects of salinity and P deficiency. These results suggest that adding P to saline soils could be an alternative for alleviating the negative effects of salinity and may ameliorate salinity tolerance.     

Effects of salt treatment on growth,lipid membrane peroxidation,polyphenol content,and antioxidant activities in leaves of Sesuvium portulacastrum L.

Changes in growth, leaf contents of proline, oxidative stress-related parameters, and phenolic compounds, and antioxidant activities were investigated in the halophyte species Sesuvium portulacastrum L. under saline conditions. Rooted cuttings were individually cultivated in sandy soil. After five weeks of pre-treatment, seedlings were submitted during one month to different salt concentrations ranging from 0 to 800?mM NaCl. The plant growth was significantly improved by salt at 200–600?mM concentration. This trend was associated with (i) the stimulation of photosynthetic activity, (ii) the protection of membrane integrity (leaf MDA content 50% lower than the control), and (iii) higher total antioxidant activity, especially at 400?mM NaCl. At this salt concentration plants accumulated high contents of proline, polyphenols, antocyanins, and carotenoids. These compounds could be implied in the protection of the photosynthetic system and in the improvement of growth. Exposure to 800?mM NaCl impaired significantly photosynthesis, proline, polyphenol, antocyanin, and carotenoid accumulation. Yet, the strong antiradical activity (DPPH) observed at this extreme salinity might partly explain the plant survival. S. portulacastrum could be used in the rehabilitation and the stabilisation of saline or saline arid land. Additionally, under saline conditions, S. portulacastrum accumulate a large amount of proline and exhibits important antioxidant potentialities.     

Insect hormone activity of p-(1,5-dimethylhexyl)benzoic acid derivatives in Dysdercus species

Derivatives of p-(1,5-dimethylhexyl)benzoic acid are juvenile hormone analogs with selective action on the hemipteran insects of the family Pyrrhocoridae. Their juvenile hormone activity is constant on five species of Dysdercus; it is about ten times lower on Pyrrhocoris, and no activity has been detected on hemipterans of some other families. Absence of profound species-specific variations in the activity suggests that the most active compounds of this type can be used as selective pesticides against all species of Dysdercus.     

Prevalence, antibiotic resistance, virulence traits and genetic lineages of Staphylococcus aureus in healthy sheep in Tunisia

Nasal swabs of 163 healthy sheep were obtained from two farms and one abattoir in Tunisia during 2010. Samples were inoculated in Baird Parker agar and ORSAB medium for Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) recovery, respectively. MRSA was detected in 5 of these 163 samples (3%) in ORSAB medium, and one isolate per sample was further studied. MRSA isolates were mecA-positive, typed as ST153-CC80-t044-agrIII, and contained blaZ, ant(6)-Ia, aph(3')-IIIa, erm(C), tet(K), and fusB genes encoding penicillin, streptomycin, kanamycin, erythromycin, tetracycline and fusidic acid resistance, respectively. These MRSA isolates showed indistinguishable or closely related PFGE-patterns and harboured the lukF/lukS gene encoding the Panton-Valentine leukocidin and the luk-ED, hla, hld, and hlg(v) genes. Methicillin-susceptible S. aureus (MSSA) were recovered in 68 of the 163 samples (41.7%) and one isolate per sample was characterized. Most of MSSA (82.4%) showed susceptibility to the tested antibiotics with exceptions: penicillin (6%, carrying blaZ gene), tetracycline (19%, carrying tet(K) gene) and fusidic acid (9%). The following toxin-genes were identified among MSSA: tst (53 isolates), luk-M (52), luk-ED, hla, hlb, hld and hlg(v) (67), hlg (1), sec (49), sel (52), and the egc-cluster-like sen-sem-sei-seo-seg (1). Ten spa-types (two of them new ones) and nine sequence types (six new ones) were detected among the 73 S. aureus isolates, and they were ascribed to agr types I and III. All MRSA and MSSA isolates were able to coagulate bovine plasma and MRSA harboured the immune-evasion-gene-cluster type E. Conclusions. Nares of healthy sheep could be a reservoir of PVL-positive community-associated-MRSA and also of TSST-positive S. aureus isolates, with potential implications in public health.     

Differential responses to phosphorus availability in the halophytes Aeluropus Littoralis,Catapodium rigidum,and Hordeum maritimum

The objective of this experiment was to explore the variability of response to phosphorus (P) availability in three fodder Poaceae species native of saline biotopes, Aeluropus littoralis, Catapodium rigidum, and Hordeum maritimum. The behavior of these wild species has been compared to that of a cultivated one, Hordeum vulgare. Plants were grown in plastic pots filled with inert sand. The experiment was carried out in a greenhouse with six P levels: 0, 5, 15, 60, 180, and 360?µM P concentration supplied as KH₂PO₄. Results showed that the growth of the four species is strongly affected by the low phosphorus availability in the medium. Furthermore, to reach 80% of their maximum yield expressed as shoot dry weight (DW), a soil phosphorus concentration of approximately 40?µM P concentration is sufficient for Hordeum maritimum, whereas approximately 66, 120, and 132?µM P concentration are needed for C. rigidum, A. littoralis, and Hordeum vulgare plants, respectively. Thus, our results showed that spontaneous species are more tolerant to P deficiency than cultivated barley. The relative performance of the three wild Poaceae species is likely related to their capacity to maintain higher P acquisition efficiency (PAE) under low P concentration conditions. These native Poaceae species may therefore represent genetic resources for the improvement of barley.