pheophytin-a and Disease-Resistance

Plant pathogens are increasingly compromising forest health, with impacts to the ecological, economic, and cultural goods and services these global forests provide. One response to these threats is the identification of disease resistance in host trees, which with conventional methods can take years or even decades to achieve. Remote sensing methods have accelerated host resistance identification in agricultural crops and for a select few forest tree species, but applications are rare. Ceratocystis wilt of 'ōhi'a, caused by the fungal pathogen Ceratocystis lukuohia has been killing large numbers of the native Hawaiian tree, Metrosideros polymorpha or 'Ōhi'a, Hawaii's most common native tree and a biocultural keystone species. Here, we assessed whether resistance to C. lukuohia is detectable in leaf-level reflectance spectra (400-2500 nm) and used chemometric conversion equations to understand changes in leaf chemical traits of the plants as indicators of wilt symptom progression. We collected leaf reflectance data prior to artificially inoculating 2-3-year-old M. polymorpha clones with C. lukuohia. Plants were rated 3x a week for foliar wilt symptom development and leaf spectra data collected at 2 to 4-day intervals for 120 days following inoculation. We applied principal component analysis (PCA) to the pre-inoculation spectra, with plants grouped according to site of origin and subtaxon, and two-way analysis of variance to assess whether each principal component separated individuals based on their disease severity ratings. We identified seven leaf traits that changed in susceptible plants following inoculation (tannins, chlorophyll a+b, NSC, total C, leaf water, phenols, and cellulose) and leaf chemistries that differed between resistant and early-stage susceptible plants, most notably chlorophyll a+b and cellulose. Further, disease resistance was found to be detectable in the reflectance data, indicating that remote sensing work could expedite Ceratocystis wilt of 'ōhi'a resistance screenings.

Topics: Ceratocystis; Child, Preschool; Chlorophyll A; Disease Resistance; Humans; Plant Leaves; Spectrum Analysis; Trees

Mungbean is an important legume mainly cultivated in Southeast Asia known for cheap source of food protein. Yellow mosaic disease (YMD) of mungbean is one of the most damaging diseases caused by mungbean yellow mosaic virus (MYMV) and mungbean yellow mosaic India virus (MYMIV) in India. The genetic basis of YMD resistance of mungbean is not well studied yet. Our present studies aimed to explore the genetic basis of YMD resistance through molecular, biochemical and metabolomics approach. Molecular analysis of YMV-infected mungbean plant materials revealed the presence of MYMIV. Chlorophyll contents were estimated as mosaic symptoms that cause chlorosis and necrosis in infected leaves. Chlorophyll a, b and total chlorophyll content were significantly reduced by 27-55% in infected samples compared non-infected control samples.

Topics: Chlorophyll A; Disease Resistance; Fabaceae; Plant Diseases; Vigna

Heavy losses by dark leaf spot disease in oilseed Brassica have incited research towards identifying sources of genetic tolerance against causal pathogen, Alternaria brassicicola. Several morpho-molecular parameters were evaluated to test the performance of field mustard and rapeseed genotypes under artificial inoculation with this pathogen. During Brassica-Alternaria interaction, physio-biochemical defense response was witnessed in tolerant genotypes. Two tolerant genotypes (one for field mustard and one for rapeseed), i.e., EC250407 and EC1494 were identified. However, necrotic lesions were more prominent in susceptible genotypes with minimum chlorophyll (chlorophyll a, chlorophyll b and total chlorophyll) and carotenoids contents. Contrary to photosynthetic pigments, increase in total soluble protein (TSP) contents was observed with disease progression in susceptible genotypes. Tolerant genotypes of field mustard and rapeseed displayed remarkable increase in the activities of redox enzyme in infected leaves with least yield loss (6.47% and 5.74%) and disease severity index (DSI) of 2.9 and 2.1, respectively. However, yield/plant showed close association with other morpho-yield parameters, photosynthetic pigments and redox enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) activities except silique length and TSP. Based on the results of morpho-biochemical analyses, redox enzymes and morphological parameters; their interplay is proposed to determine the tolerance outcome of the Brassica-A. brassicicola interaction.

Topics: Alternaria; Antioxidants; Brassica napus; Brassica rapa; Brassicaceae; Carotenoids; Catalase; Chlorophyll; Chlorophyll A; Disease Resistance; Genotype; Oxidation-Reduction; Photosynthesis; Plant Diseases; Superoxide Dismutase

Previous studies have shown that Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), is able to colonize remote areas in infected plants of Ulmus such as the leaf midrib and secondary veins. The objective of this study was to compare the performances in leaf traits between two Dutch elm hybrids 'Groeneveld' and 'Dodoens' which possess a contrasting tolerance to DED. Trait linkages were also tested with leaf mass per area (LMA) and with the reduced Young's modulus of elasticity (MOE) as a result of structural, developmental or functional linkages.. Measurements and comparisons were made of leaf growth traits, primary xylem density components, gas exchange variables and chlorophyll a fluorescence yields between mature plants of 'Groeneveld' and 'Dodoens' grown under field conditions. A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to reveal nanomechanical properties of the cell walls of tracheary elements such as MOE, adhesion and dissipation.. 'Dodoens' had significantly higher values for LMA, leaf tissue thickness variables, tracheary element lumen area (A), relative hydraulic conductivity (RC), gas exchange variables and chlorophyll a fluorescence yields. 'Groeneveld' had stiffer cell walls of tracheary elements, and higher values for water-use efficiency and leaf water potential. Leaves with a large carbon and nutrient investment in LMA tended to have a greater leaf thickness and a higher net photosynthetic rate, but LMA was independent of RC. Significant linkages were also found between the MOE and some vascular traits such as RC, A and the number of tracheary elements per unit area.. Strong dissimilarities in leaf trait performances were observed between the examined Dutch elm hybrids. Both hybrids were clearly separated from each other in the multivariate leaf trait space. Leaf growth, vascular and gas exchange traits in the infected plants of 'Dodoens' were unaffected by the DED fungus. 'Dodoens' proved to be a valuable elm germplasm for further breeding strategies.

Topics: Chimera; Chlorophyll; Chlorophyll A; Disease Resistance; Fluorometry; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Ophiostoma; Photosynthesis; Plant Diseases; Plant Leaves; Plant Transpiration; Trees; Ulmus; Wood; Xylem