A Jasmonate-Induced Defense Elicitation in Mature Leaves Reduces Carbon Export and Alters Sink Priority in Grape (Vitis vinifera Chardonnay)

This work aims to understand how Vitis vinifera (Chardonnay) vines prioritise the export and distribution of recently fixed photoassimilate between root tissue, fruit, and defence, following the elicitation of a defence response. Jasmonic acid (JA) and its methyl ester, MeJA, are endogenous plant hormones, known collectively as jasmonates, that have signalling roles in plant defence and consequently are often used to prime plant defence systems. Here, we use exogenous jasmonate application to mature source leaves of Chardonnay grapevines to elucidate the prioritisation strategy of carbon allocation between plant defence and growth. Our results demonstrate that jasmonate application to Chardonnay leaves can elicit a defence response to Botrytis cinerea, but the effect was localised to the jasmonate-treated area. We found no evidence of a systemic defence response in non-treated mature leaves or young growing tissue. JA application reduced the photosynthetic rate of the treated leaf and reduced the export rate of recently fixed carbon-11 from the leaf. Following JA application, a greater proportion of available recently fixed carbon was allocated to the roots, suggesting an increase in sink strength of the roots. Relative sink strength of the berries did not change; however, an increase in berry sugar was observed seven days after JA treatment. We conclude that the data provide evidence for a “high sugar resistance” model in the mature treated leaves of the vine, since the export of carbon was reduced to ensure an elevated defence response in the treated leaf. The increase in berry sugar concentration seven days after treatment can be explained by the initial prioritisation of a greater portion of the exported carbon to storage in the roots, making it available for remobilisation to the berries once the challenge to defence had passed.

Produs nou biorațional pentru combaterea dăunătorilor în spaţii protejate

The article presents the results of pesticidal activity study of product elaborated on the neem oil base. Bioassays were performed on aphids and spider mites in order to compare the pesticidal activity of new preparative form NEEM-01 with that of the commercial biorational products Pelecol and MatrinBio. The product NEEM- 01at a dose of 10 l/ ha has potential as aphicide and acaricide, although in terms of efficacy in controlling aphids and mites it is different. NEEM-01 was quite effective against the aphid population compared to spider mites, which are more mobile, ceasing to feed on the treated leaf. A higher mortality of pests with higher biological efficacy of NEEM- 01 was achieved after two treat-ments with an interval of 10 days between them. The results are preliminary, the research continues.

Absorption and Translocation of [14c]2,4-Dichlorophenoxyacetic Scid in Herbicide-tolerant Chromosome Substitution Lines of Gossypium Hirsutum L.

Upland cotton is sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D), and the identification of potentially 2,4-D tolerant cotton chromosome substitution (CS) lines and understanding tolerance mechanisms provide a significant step into the development and genetic improvement of upland cotton to reduce yield loss caused by 2,4-D herbicide effects including the drifts. Experiments were conducted to understand the possible mechanism of herbicide tolerance in CS-T04-15, CS-T07, and CS-B15sh, 2,4-D herbicide-tolerant cotton CS lines compared with TM-1, the 2,4-D herbicide susceptible recurrent parent of the CS line as control, using [14C]2,4-D. Percent absorption rate and translocation patterns of the 14C-labeled herbicide application at 5.17 kBq at 6 to 48 hours after treatment (HAT) were determined. The tolerant cotton CS lines showed 15-19% [14C]2,4-D uptake while TM-1 exhibited a reduced uptake of only 1.4% [14C]2,4-D at 24 HAT. Distribution of the absorbed [14C]2,4-D showed that 2-5% was translocated outside the treated leaf. In TM-1, 77% of the herbicide was translocated above and below the treated leaf, contrasting with the reduced translocation of 14C-labeled herbicide observed in the tolerant CS lines. Interestingly, CS-T04-15 showed a restricted movement of 14C below the treated leaf at 6 to 48 HAT, suggesting a novel mechanism of herbicide tolerance. This finding is the first report on upland cotton demonstrating a complex differential uptake and translocation associated with herbicide tolerance for [14C]2,4-D in cotton CS lines.

Non-Target Site Mechanisms Endow Resistance to Glyphosate in Saltmarsh Aster (Aster squamatus)

Of the six-glyphosate resistant weed species reported in Mexico, five were found in citrus groves. Here, the glyphosate susceptibility level and resistance mechanisms were evaluated in saltmarsh aster (Aster squamatus), a weed that also occurs in Mexican citrus groves. The R population accumulated 4.5-fold less shikimic acid than S population. S plants hardly survived at 125 g ae ha−1 while most of the R plants that were treated with 1000 g ae ha−1, which suffered a strong growth arrest, showed a vigorous regrowth from the third week after treatment. Further, 5-enolpyruvylshikimate-3-phosphate basal and enzymatic activities did not diverge between populations, suggesting the absence of target-site resistance mechanisms. At 96 h after treatment, R plants absorbed ~18% less glyphosate and maintained 63% of the 14C-glyphsoate absorbed in the treated leaf in comparison to S plants. R plants metabolized twice as much (72%) glyphosate to amino methyl phosphonic acid and glyoxylate as the S plants. Three non-target mechanisms, reduced absorption and translocation and increased metabolism, confer glyphosate resistance saltmarsh aster. This is the first case of glyphosate resistance recorded for A. squamatus in the world.

In vitro biological activity of ethanolic extracts from plants of the Meliaceae family on Diaphorina citri Kuwayama 1908 (Hemiptera: Liviidae)

In vitro effect of ethanolic extracts of Azadirachta indica seeds, Melia azedarach and Swietenia humilis (Meliaceae) were evaluated on the mortality, repellency and oviposition of Diaphorina citri (Hemiptera: Liviidae). Toxicity was determined by the placement of adults and nymphs on orange leaf discs (Citrus sinensis cv. Valencia) previously sprayed or immersed in the treatments. The repellency was estimated through an exposition of adults to the treated leaf, in an experimental arena for 24 h. In order to inhibit oviposition, Murraya paniculata sprouts sprinkled with 2.5 mL of solution were used. The ethanolic extracts from the three meliaceus showed toxicity on nymphs and adults; however, adults evidenced the toxic effect as of 100.0 mg/mL, while nymphs did at 4.10 mg/mL. With a repellent effect, the 100 mg/mL solution stands out, with 82 and 78% for A. indica and S. humilis, respectively; effect associated to the concentration and the time. The oviposition was affected by ethanolic extracts of S. humilis and A. indica at 100.0 mg/mL. It is inferred that the ethanol extracts from S. humilis and A. indica present potential to be considered in the development of alternatives for the integrated management of D. citri.

Effects of Zinc Oxide Nanoparticles on Physiological and Anatomical Indices in Spring Barley Tissues

The aim of the present work was to investigate the toxic effects of zinc oxide nanoparticles (ZnO NPs, particle size < 50 nm) on the physiological and anatomical indices of spring barley (Hordeum sativum L.). The results show that ZnO NPs inhibited H. sativum growth by affecting the chlorophyll fluorescence emissions and causing deformations of the stomatal and trichome morphology, alterations to the cellular organizations, including irregularities of the chloroplasts, and disruptions to the grana and thylakoid organizations. There was a lower number of chloroplasts per cell observed in the H. sativum leaf cells treated with ZnO NPs as compared to the non-treated plants. Cytomorphometric quantification revealed that ZnO NPs decreased the size of the chloroplast by 1.5 and 4 times in 300 and 2000 mg/L ZnO NP-treated plants, respectively. The elemental analysis showed higher Zn accumulation in the treated leaf tissues (3.8 and 10.18-fold with 300 and 2000 mg/L ZnO NPs, respectively) than the untreated. High contents of Zn were observed in several spots in ZnO NP-treated leaf tissues using X-ray fluorescence. Deviations in the anatomical indices were significantly correlated with physiological observations. The accumulation of Zn content in plant tissues that originated from ZnO NPs was shown to cause damage to the structural organization of the photosynthetic apparatus and reduced the photosynthetic activities.

TREATMENT EFFECT OF LEUCAENA LEAF MEAL ON THE CARCASS CHARACTERISTICS OF RABBITS.

A total of forty five white rabbit weaners were fed for 8 weeks on a control diet and four other diets containing 20% Leucaena leucocephala leaves that have been subjected to sun drying, ensilage, heat treatment or soaking in water. The rabbits fed the diet containing ensilled leucaena leaves had the least feed intake, daily weight gain and in general performed worse than rabbits on any other diet in most of the parameters evaluated. The rabbits fed the heat treated leaf meal diet ranked next to those fed the control diet which performed best in most of the parameters evaluated. The rabbits fed the diet containing sun dried leaves experienced alopecia. In general, the results obtained indicate that heat treated leucaena leaves could serve as a dry season feed ingredient for rabbits in the tropics.

Modification of Olive Leaves’ Surface by Ultrasound Cavitation. Correlation with Polyphenol Extraction Enhancement

We investigated the impact of ultrasound at 20 kHz on olive leaves to understand how acoustic cavitation could increase polyphenol extraction. Application of ultrasound to whole leaf from 5 to 60 min enabled us to increase extraction from 6.96 to 48.75 µg eq. oleuropein/mL of extract. These results were correlated with Environmental Scanning Electron Microscopy, allowing for leaf surface observation and optical microscopy of treated leaf cross sections to understand histochemical modifications. Our observations suggest that the effectiveness of ultrasound applied to extraction is highly dependent on plant structure and on how this material will react when subjected to acoustic cavitation. Ultrasound seems to impact the leaves by two mechanisms: cuticle erosion, and fragmentation of olive leaf surface protrusions (hairs), which are both polyphenol-rich structures.

Can Control of Glyphosate Susceptible and Resistant Conyza sumatrensis Populations Be Dependent on the Herbicide Formulation or Adjuvants?

In this work, we studied the effect of three glyphosate formulations (isopropylamine, ammonium and potassium salts) and two non-ionic adjuvants on the resistance response of two resistant (R1, R2) and one susceptible population of the highly invasive Asteraceae, Conyza sumatrensis, from Southern France vineyards. Only in R1, an amino acid substitution (Pro106Thr) was found in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The two adjuvants, in a similar fashion, significantly reduced GR50 values for every population and glyphosate formulation. Without adjuvants, glyphosate as potassium salt was the only formulation able to significantly reduce the GR50 values of every population. For every population, the two adjuvants improved, indistinguishably, leaf retention of the herbicidal solution and the potassium salt formulation led to the highest retention, both with and without the adjuvant added. Uptake responses paralleled those of retention and adjuvant addition was more effective in increasing foliar uptake of the lower performing formulations (isopropylamine and ammonium salts). The allocation pattern of glyphosate among plant compartments was only dependent on population, with R2 retaining most glyphosate in the treated leaf, clearly suggesting the occurrence of a Non-Target Site Resistance (NTSR) mechanism. Results indicate that control of weed populations possessing NTSR mechanisms of resistance to glyphosate may be improved through adequate selection of formulation and adjuvant use.

Vernalization affects absorption and translocation of clopyralid and aminopyralid in rush skeletonweed (Chondrilla juncea)

The developmental status of perennial weeds such as rush skeletonweed (Chondrilla juncea L.) can influence herbicide absorption and translocation. Differential efficacy between fall and spring applications suggests vernalization impacts herbicide absorption and translocation in other perennial asters. Clopyralid and aminopyralid absorption and translocation were quantified in nonvernalized and vernalized plants following application of 14C-labeled herbicides 2, 4, 8, 24, and 72 h after treatment. Less 14C clopyralid was absorbed, and at a slower rate, in vernalized plants. Movement out of the treated leaf was slower, with 14C clopyralid translocating more rapidly than 14C aminopyralid. More 14C moved to the roots in nonvernalized plants compared with vernalized plants, regardless of herbicide. Increased translocation to belowground survival structures is needed for effective control of C. juncea.