An in Vitro Approach to Investigate the Role of Abscisic Acid in Alleviating the Negative Effects of Chilling Stress on Banana Shoots

Banana is a tropical crop cultivated in warm places.Chilling stress in Egypt is making banana crops less productive.Abscisic acid(ABA),a key plant hormone,regulates metabolic and physiological processes and protects plants from a variety of stresses.In vitro growing banana shoots were pre-treated with ABA at four concentrations(0,25,50,and 100 mM)and chilled at 5℃for 24 h,followed by a six-day recovery period at 25℃.By comparing ABA treatments to both positive and negative controls,physiological and biochemical changes were investigated.Chilling stress(5℃)caused a considerable increase in lipid peroxidation and ion leakage and reduced photosynthetic pigments in cold-treated plantlets.Increasing the concentration of ABA to 100μM enhanced the response to chilling stress.ABA had a major effect on mitigating chilling injury in banana shoots by keeping cell membranes stable and lowering the amount of ion leakage and lipid peroxidation.Also,ABA significantly maintained the photosynthetic pigment concentration of banana shoots;accumulated higher amounts of total soluble carbohydrates and proline;and increased DPPH radical scavenging activity.Furthermore,ABA treatment enhanced cold tolerance in chilling-stressed banana shoots through the regulation of antioxidant enzyme activity.Overall,the results show that ABA is a good choice for protecting banana shoots from the damage caused by chilling stress.

Seed Germination Traits of Loquat (Eriobotrya japonica Lindl.) as Affected by Various Pre-Sowing Treatments (Cutting of Cotyledons, Removal of Perisperm, Moist Chilling and/or Exogenous Application of Gibberellin)

The purpose of this study was to investigate the effects of various presowing treatments on the germinability(final germination percentage)and germination rate of loquat seeds in order to increase seedling production in nurseries(applied research)as well as provide answers for important physiological issues related to loquat seeds and their seed coat(basic research).Three experiments were carried out with various pre-sowing treatments.These treatments included full or partial removal of seed coat(perisperm),partial cutting of cotyledons as well as moist chilling at 5℃ for 13 days and/or soaking the seeds in water or 250 ppm gibberellic acid(GA_(3))solution for 24 h.According to the results,cotyledons excision resulted in delayed germination,regardless of the presence or absence of the seed coat in comparison with the decoated seeds that demonstrated the highest germination rate amongst them.In addition,even the partial excision of seed coats affected positively both the germinability and the germination rate,compared to the control-intact seeds.Furthermore,control-intact seeds had a higher germination percentage when exposed to moist chilling independently of the application or not of gibberellin;while the combination of gibberellin application and moist chilling improved both the percentage and the rate of germination of decoated seeds.In conclusion,the role of perisperm(seed coat)in the germination procedure of loquat seeds seems to be important,indicating the existence of seed coat-imposed dormancy on loquat seeds.Finally,the existence of a mild endogenous embryo-dormancy on loquat is also discussed.

Decoding altitude-activated regulatory mechanisms occurring during apple peel ripening

Apple(Malus domestica Borkh)is an important fruit crop cultivated in a broad range of environmental conditions.Apple fruit ripening is a physiological process,whose molecular regulatory network response to different environments is still not sufficiently investigated and this is particularly true of the peel tissue.In this study,the influence of environmental conditions associated with low(20 m)and high(750 m)altitude on peel tissue ripening was assessed by physiological measurements combined with metabolomic and proteomic analyses during apple fruit development and ripening.Although apple fruit ripening was itself not affected by the different environmental conditions,several key color parameters,such as redness and color index,were notably induced by high altitude.Consistent with this observation,increased levels of anthocyanin and other phenolic compounds,including cyanidin-3-O-galactoside,quercetin-3-O-rhamnoside,quercetin-3-O-rutinoside,and chlorogenic acid were identified in the peel of apple grown at high altitude.Moreover,the high-altitude environment was characterized by elevated abundance of various carbohydrates(e.g.,arabinose,xylose,and sucrose)but decreased levels of glutamic acid and several related proteins,such as glycine hydroxymethyltransferase and glutamate–glyoxylate aminotransferase.Other processes affected by high altitude were the TCA cycle,the synthesis of oxidative/defense enzymes,and the accumulation of photosynthetic proteins.From the obtained data we were able to construct a metabolite-protein network depicting the impact of altitude on peel ripening.The combined analyses presented here provide new insights into physiological processes linking apple peel ripening with the prevailing environmental conditions.

Whole genome re-sequencing of sweet cherry(Prunus avium L.)yields insights into genomic diversity of a fruit species

Sweet cherries,Prunus avium L.(Rosaceae),are gaining importance due to their perenniallity and nutritional attributes beneficial for human health.Interestingly,sweet cherry cultivars exhibit a wide range of phenotypic diversity in important agronomic traits,such as flowering time and defense reactions against pathogens.In this study,wholegenome resequencing(WGRS)was employed to characterize genetic variation,population structure and allelic variants in a panel of 20 sweet cherry and one wild cherry genotypes,embodying the majority of cultivated Greek germplasm and a representative of a local wild cherry elite phenotype.The 21 genotypes were sequenced in an average depth of coverage of 33.91×.and effective mapping depth,to the genomic reference sequence of‘Satonishiki’cultivar,between 22.21×to 36.62×.Discriminant analysis of principal components(DAPC)with SNPs revealed two clusters of genotypes.There was a rapid linkage disequilibrium decay,as the majority of SNP pairs with r2 in near complete disequilibrium(>0.8)were found at physical distances less than 10 kb.Functional analysis of the variants showed that the genomic ratio of non-synonymous/synonymous(dN/dS)changes was 1.78.The higher dN frequency in the Greek cohort of sweet cherry could be the result of artificial selection pressure imposed by breeding,in combination with the vegetative propagation of domesticated cultivars through grafting.The majority of SNPs with high impact(e.g.,stop codon gaining,frameshift),were identified in genes involved in flowering time,dormancy and defense reactions against pathogens,providing promising resources for future breeding programs.Our study has established the foundation for further large scale characterization of sweet cherry germplasm,enabling breeders to incorporate diverse germplasm and allelic variants to fine tune flowering and maturity time and disease resistance in sweet cherry cultivars.

Mass production, fermentation, formulation of <i>Pseudomonas putida</i>for controlling of die back and phomopsis diseases on grapevine

The export oriented agricultural and horticultural crops depends on the export of residue free produce and has created a great potential and demand for the incorporation of biopesticides in crop protection. PGPR with wide scope for commercialization includes Pseudomonas putida. Pseudomonas putida was effective in reducing die back caused by a fungus Botryodiplodia theobromae and phomopsis or arm death, caused by a fungus, Phomopsis viticola of grapevine in vitro and in vivo. Pseudomonas putida showed optimum Siderophore pseudobactin production at 72 h, and growth peak at 120 h. glycerol as a source of carbon and yeast as a source of nitrogen Pseudomonas putida was formulated using polysaccharide dextran starch, which led to the elongation of conservation and the effectiveness of the biofungicide. Pseudomonas putida was very effective as biocontrol agents to reduce the die back and phomopsis diseases on grapevine. The obtained results showed that both bacterial treatments significantly increased the growth parameters as well as fruits dry weights and yield of grapevine.

Synthesis of an eco-friendly nanocomposite fertilizer for common bean based on carbon nanoparticles from agricultural waste biochar

The burning of agricultural waste is a major cause of environmental pollution.In this study,we sought to prepare biochar from agricultural waste as a source material for the preparation of carbon nanoparticles(CNPs).Surface morphology,hydrodynamic particle size,and purity and crystallinity of CNPs were extensively investigated using transmission electron microscopy(TEM),zeta sizing,and X-ray diffraction(XRD)spectroscopy,respectively.The CNPs were subsequently immersed in a solution of potassium nitrate(KNO_(3))to prepare a CNPs/NK nanocomposite(CNPs loaded with nitrogen(N)and potassium(K))as a nanocomposite fertilizer for common bean(Phaseolus vulgaris L.).The CNPs/NK nanocomposite was sprayed as a foliar fertilizer at 0,10,20,30,and 40 mg L^(-1) on common bean plants 25 d after sowing on a farm in Shebin El-Kom,El-Monifia,Egypt.The growth,yield,and quality of common bean were investigated during two successive growing seasons(2017 and 2018).The highest seed yields of 2.04 and 2.01 t ha^(-1) and the highest values of growth parameters including plant height of 61.5 and 59.2 cm,number of leaves per plant of 35 and 35,number of flowers per plant of 83.3 and 82.7,and plant fresh weight of 148.7 and 152.8 g plant^(-1) were obtained when using the CNPs/NK nanocomposite at a concentration of 20 mg L^(-1) during the 2017 and 2018 growing seasons,respectively.