Histochemical techniques in plant science: more than meets the eye

Histochemistry is an essential analytical tool interfacing extensively with plant science. The literature is indeed constellated with examples showing its use to decipher specific physiological and developmental processes, as well as to study plant cell structures. Plant cell structures are translucent unless they are stained. Histochemistry allows the identification and localization, at the cellular level, of biomolecules and organelles in different types of cells and tissues, based on the use of specific staining reactions and imaging. Histochemical techniques are also widely used for the in vivo localization of promoters in specific tissues, as well as to identify specific cell wall components such as lignin and polysaccharides. Histochemistry also enables the study of plant reactions to environmental constraints, e.g. the production of reactive oxygen species (ROS) can be traced by applying histochemical staining techniques. The possibility of detecting ROS and localizing them at the cellular level is vital in establishing the mechanisms involved in the sensitivity and tolerance to different stress conditions in plants. This review comprehensively highlights the additional value of histochemistry as a complementary technique to high-throughput approaches for the study of the plant response to environmental constraints. Moreover, here we have provided an extensive survey of the available plant histochemical staining methods used for the localization of metals, minerals, secondary metabolites, cell wall components, and the detection of ROS production in plant cells. The use of recent technological advances like CRISPR/Cas9-based genome-editing for histological application is also addressed. This review also surveys the available literature data on histochemical techniques used to study the response of plants to abiotic stresses and to identify the effects at the tissue and cell levels.The authors would like to thank Head of the Department, University of Allahabad, Allahabad, India, for providing the necessary facilities to carry out the work

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Not AvailableThree Vertisols from Nagpur, Amravati and Akola districts were studied in detail to understand the relation between moisture and soil properties. These soils are deep and during dry periods cracks cut through the slickensides in some soils with subsoil sodicity. A significant positive correlation between available water content (AWC) and smectite content, exchangeable sodium percentage (ESP) and exchangeable magnesium percentage (EMP) indicates the nature of clay and cations in exchange site plays an important role in retaining and releasing moisture. Studies on biophysical factors on water retention and release, and cotton yield in 32 Vertisols indicate that the determination of AWC and PAWC at 33 and 1500 kPa overestimates the soil moisture content because in field conditions soil water in the subsoil do not reach the saturation at 33kPa due to low to very low saturated hydraulic conductivity. A significant positive correlation between PAWC (estimated at 100-1500 kPa for non-sodic and 300-1500 kPa for sodic soils), and yield of cotton indicates that the PAWC estimated by this method can be considered as an important biophysical parameter for evaluation of rain fed Vertisols for growing deep rooted crops in Indian states in general and Vidarbha region of Maharashtra state in particular.Not Availabl

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Not AvailableHydroxy-interlayerig (HI) in soil clay smectites of Vertisols in Peninsular India is a common phenomenon. Presence of small to moderate amounts of HI also affects the properties of soils. Earlier the view was that pH higher than 7.5 in soils may be the reason for HI. However, this explanation did not work in soil clay smectites of sodic Vertisols of Anantapur district of Andhra Pradesh and Purna valley of Maharashtra as the smectites in these areas are not hydroxy-interlayered. This demanded investigation for possible source and reason of HI in the soil clay smectites. Clay smectites of some Vertisols from Maharashtra (Takarkheda, Seloo and Saikhindi series) had small (about 3-5% in Seloo and Saikhindi) to moderate (about 5-15% in Takarkheda) HI. Mineralogical analysis by X-ray diffraction of soil clays indicated presence of HI, that were identified by (1) the nature of the graphs of K-saturated samples heated from 110° to 550°C; the peak at 1.0 nm was greatly reinforced with tailing on its low angle sides. In absence of chlorite, the 1.4 nm peak indicated hydroxy-interlayered smectite (HIS), (2) intensity of Ca-treated samples were higher than the Ca-EG treated samples which indicated presence of HIS and (3) persistence of 1.4 nm peak (after Greene-Kelly test) confirmed presence of HIS. The hydroxy-interlayered materials in hydroxy-interlayered smectities (HIS) are positively charged hydroxy-cations such as [Al3(OH)4]5+, [Al6(OH)15]3+, [Fe3(OH)6]3+, [Mg2Al(OH)6]+, etc. The positively charged hydroxy-cations are usually formed under acid weathering conditions in a humid tropical climate where substantial amount of Fe3+, Al3+, Mg2+ are available. Hence, the transformation of smectite to HIS by inclusion of hydroxy-cations would require acid weathering under humid tropical environment. In contrast, the study area where the Vertisols are formed have a semi-arid climate and a moderately to strongly alkaline conditions. This suggests that the presence of HIS in the study area representing semi-arid climate and having alkaline conditions is unlikely to favour the formation of HIS. Thus, the reactions involving hydroxy-interlayering is not a contemporary pedogenic process under semi-arid climatic conditions. The HIS which has been produced in the humid tropical area may have been transported through rivers and streams. After this depositional episode in wetter climate, soils became calcareous due to the change of climate to semi-arid. Thus, the HIS remained as a signature of climate change phenomenon.Not Availabl

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Not AvailableShrink-swell (Vertisols and their intergrades) soils cover an extensive area especially in Peninsular India with smectites as the dominant mineral. It was felt necessary to find out the species of smectites for better management of these soils. Hence, two benchmark Vertisols namely Seloo from Wardha and Saikhindi from Ahmadnagar districts of Maharashtra were chosen for the study. High resolution mineralogical analysis employed through X ray diffraction (XRD) techniques of the silt, total clay and fine clay fractions of both the pedons were carried out along with Greene-Kelly test with only fine clays. Silt (50-2 μm), total clay (<2 μm) and fine clay (<0.2 μm) fractions are dominated by smectite in both the soils; the smectites content increased gradually with decreasing size fraction. The fine clay fractions are mostly composed of smectite with small amounts of vermiculite and traces of chlorite, kaolin and feldspar. Greene-Kelly test indicated that both Seloo and Saikhindi soil fine clays are dominated by beidellite/nontronite over montmorillonite. The Seloo fine clay smectite is composed of 18-26 per cent and 74-82 per cent montmorillonite and beidellite/nontronite, respectively, and for Saikhindi it is composed of 32-41 per cent and 59-68 per cent for montmorillonite and beidellite/nontronite, respectively. However, these fine clay smectites are of low charge dioctahedral nature and therefore may not have any K selectivity. This property appears to have implications in K management of shrink-swell soils of Deccan basalt areas.Not Availabl

The Incidence of Helminth Parasites in Donkeys

The faeces of 82 donkeys irrespective of sex and age were collected and examined for any parasitic ova. The faecal sample of68 donkeys were infected with: Strongylus sp. (54.87%), Parascaris sp. (29.26%), Strongyloides sp. (24.39%), Trichonema sp. (15.85%),Oxyuris sp. (8.53%), Gastrodiscus sp. (8.53%), Entamoeba sp. (8.53%), Dictyocaulus sp. (3.65%), and Triodontophorus sp. (2.43%). [Vet World 2009; 2(6.000): 224-224