New genetic resources for aphid resistance were identified from a newly developed wheat mutant library

Reports on development of resilient wheat mutants to aphid infestation-causing heavy losses to wheat production in many parts of the world, are scanty. The present study aimed to identify genetic diversity of wheat mutants in terms of varying degree of resistance to aphid infestation which can help protect wheat crop, improve yields and enhance food security. Resistance response to aphid infestation was studied on newly developed 33 wheat mutants, developed through irradiating seed of an elite wheat cultivar "Punjab-11" with gamma radiations, during three normal growing seasons at two sites. Data on various traits including aphid count per plant, biochemical traits, physiological traits and grain yield was recorded. Meteorological data was also collected to unravel the impact of environmental conditions on aphid infestation on wheat plants. Minimum average aphid infestation was found on Pb-M-2725, Pb-M-2550, and Pb-M-2719 as compared to the wild type. High yielding mutants Pb-M-1323, Pb-M-59, and Pb-M-1272 supported the moderate aphid infestation. The prevailing temperature up to 25 °C showed positive correlation (0.25) with aphid count. Among biochemical traits, POD (0.34), TSP (0.33), TFA (0.324) exhibited a high positive correlation with aphid count. In addition, CAT (0.31), TSS (0.294), and proline content (0.293) also showed a positive correlation with aphid count. However, all physiological traits depicted negative correlation with aphid count, while, a very weak correlation (0.12) was found between mean aphid count and grain yield. In PCA biplots, the biochemical variables clustered together with aphid count, while physiological variables grouped with grain yield. Biochemical parameters contributed most, towards first dimension of the PCA (48.6%) as compared to the physiological variables (13%). The FAMD revealed that mutant lines were major contributor towards total variation; Pb-M-1027, Pb-M-1323, Pb-M-59 were found to be the most diverse lines. The PCA revealed that biochemical parameters played a significant role in explaining variations in aphid resistance, emphasizing their importance in aphid defense mechanisms. The identified mutants can be utilized by the international wheat community for getting insight into the molecular circuits of resistant mechanism against aphids as well as for designing new KASP markers. This study also highlights the importance of considering both genetic and environmental factors in the development of resilient wheat varieties and pave the way for further investigations into the molecular mechanisms underpinning aphid resistance in wheat.

Eco-physiological trait variation in widely occurring species of Western Himalaya along elevational gradients reveals their high adaptive potential in stressful conditions

Species distributed across a wide elevation range have broad environmental tolerance and adopt specific adaptation strategies to cope with varying climatic conditions. The aim of this study is to understand the patterns of variation in leaf eco-physiological traits that are related to the adaptation of species with a wide distribution in different climatic conditions. We studied the variability in eco-physiological traits of two co-occurring species of Western Himalaya (Rumex nepalensis and Taraxacum officinale), along elevational gradients. We conducted our study in elevations ranging from 1000 to 4000 m a.s.l. in three transects separated in an eco-region spanning 2.5° latitudes and 2.3° longitudes in the Western Himalaya. We hypothesized substantial variation in eco-physiological traits, especially increased net rate of photosynthesis (PN), Rubisco specific activity (RSA), and biochemicals at higher elevations, enabling species to adapt to varying environmental conditions. Therefore, the photosynthetic measurements along with leaf sampling were carried out during the months of June-August and the variations in photosynthetic performance and other leaf traits were assessed. Data was analyzed using a linear mixed effect model with 'species,' 'elevation' as fixed and 'transect' as random factor. Elevation had a significant effect on majority of traits. It was found that PN and maximum carboxylation rate of Rubisco (Vcmax) have unimodal or declining trend along increasing elevations. High RSA was observed at higher elevations in all the three transects. Trends for biochemical traits such as total soluble sugars, total soluble proteins, proline, and total phenolics content suggested an increase in these traits for the survival of plants in harsh environments of higher elevations. Our study reveals that although there is considerable variation in the eco-physiological traits of the two species across elevational gradients of different transects, there are certain similarities in the patterns that depict their high adaptive potential in varying climatic conditions.

Is intraspecific trait differentiation in Parthenium hysterophorus a consequence of hereditary factors and/or phenotypic plasticity?

Of the various strategies adopted by an invasive plant species for expanding its niche breadth, phenotypic differentiation (either due to plasticity and/or adaptive evolution) is proven to be the most successful. Lately, we studied the persistence of substantial morpho-functional variations within the individuals of alien invasive plant, Parthenium hysterophorus in Chandigarh, India, through field surveys. Based on observed differences, the individuals were categorized into two morphotypes, PA and PB. PA had higher leaf area, leaf biomass, and chlorophyll content as compared with PB. However, PB had a higher stem circumference, stem specific density, twig dry matter content, profuse branching, bigger canopy, and better reproductive output than PA. To substantiate the persistence of intraspecific variations in P. hysterophorus and to deduce the possible genesis of these variations, we propagated both the morphotypes under experimental conditions in winter and summer. Apart from the key morpho-functional differences observed during the field studies, protein and carbohydrate metabolism were studied in leaves and roots of the propagated plants. Differences in plant metabolism were observed only during the early growth period, whereas the morpho-functional traits varied in the mature flowering plants. The effect of growth season was highly significant on all the studied morpho-functional and biochemical parameters (p ≤ 0.05). Parent morphotypes (P) and interactions between morphotypes and seasons significantly affected several growth parameters (p ≤ 0.05). The analyses revealed that the contrasting growth conditions at the time of transplantation and early growth may regulate the phenotype of P. hysterophorus. The pattern of intraspecific variations observed during the study is justified to consider morphotype PA as winter biotype and morphotype PB as summer biotype of P. hysterophorus. The study points towards the role of plasticity or a combination of genetic and environmental (G × E) factors in producing the phenotypic variability observed in the population of P. hysterophorus.

The potentiality of biostimulant (Lawsonia inermis L.) on some morpho-physiological, biochemical traits, productivity and grain quality of Triticum aestivum L

BACKGROUND

In conformity with the international trend to substitute the artificial agro-chemicals by natural products to improve growth and productivity of crops, there is a necessity to focus on the environment sustainable and eco-friendly resources to increase crops productivity per unit area. One of these resources is the use of biostimulants. The aim of this study is to allow the vertical expansion of wheat crop by improving its growth and productivity per unit area as well as enhancing its grain quality using henna leaf extract as a biostimulant.

RESULTS

Field study was conducted to evaluate the potentiality of different doses of henna leaf extract (HLE) for improving the performance of wheat plants (Triticum aestivum L.) at three development stages. Results revealed that the response was dose dependent hence both 0.5 and 1.0 g/L doses significantly enhanced the growth of shoot and root systems, biochemical traits, yield and yield related components with being 1.0 g/L the most effective one. Furthermore, 1.0 g/L HLE markedly enhanced the quality of the yielded grains as revealed by increasing the content of soluble sugars (23%), starch (19%), gluten (50%), soluble proteins (37%), amylase activity (27%), total phenolics, flavonoids and tannins (67, 87 and 23%, respectively) as well as some elements including Ca (184%), Na and Fe (10%). Also, HPLC analysis of grains revealed that 1.0 g/L dose significantly increased the level of different phytohormones, soluble sugars and flavonoids (quercetin, resveratrol and catechin).

CONCLUSION

Application of Henna (Lawsonia inermis) leaf extract at 1.0 g/L dose as a combination of seed priming and foliar spray can be recommended as a nonpolluting, inexpensive promising biostimulant, it can effectively enhance wheat growth, biochemical traits and productivity as well as improving the quality of the yielded grains.

Influence of polyvinyl chloride microplastic on chromium uptake and toxicity in sweet potato

The extensive use of plastic products and rapid industrialization have created a universal concern about microplastics (MPs). MPs can pose serious environmental risks when combined with heavy metals. However, current research on the combined effects of MPs and hexavalent chromium [Cr(VI)] on plants is insufficient. Herein, a 14-day hydroponic experiment was conducted to investigate the impact of PVC MPs (100 and 200 mg/L) and Cr(VI) (5, 10, and 20 μM) alone and in combination on sweet potato. Results showed that combined Cr(VI) and PVC MPs affected plant growth parameters significantly, but PVC MPs alone did not. The combined application of PVC MPs and Cr(VI) resulted in a decrease in plant height (24-65%), fresh biomass per plant (36-71%), and chlorophyll content (16-34%). Cr(VI) bioaccumulation increased with the increase in its doses, with the highest concentration of Cr(VI) in the leaves (16.45 mg/kg), stems (13.81 mg/kg), and roots (236.65 mg/kg). Cr(VI) and PVC MPs-induced inhibition varied with Cr(VI) and PVC MPs doses. Osmolytes and antioxidants, lipid peroxidation, and H₂O₂ contents were significantly increased, while antioxidant enzymes except CAT were decreased with increasing Cr(VI) concentration alone and mixed treatments. The presence of PVC MPs promoted Cr(VI) accumulation in sweet potato plants, which clearly showed severe toxic effects on their physio-biochemical characteristics, as indicated by a negative correlation between Cr(VI) concentration and these parameters. PVC MPs alone did not significantly inhibit these parameters. The findings of this study provide valuable implications for the proper management of PVC MPs and Cr(VI) in sweet potato plants.

Physio-biochemical characterization of wheat genotypes under temperature stress

Thermal stress is a major abiotic stress in wheat and is highly complex in mechanism. A large area in northwestern plain zones (NWPZ), which is the wheat bowl of India is affected by heat stress. Climate change also causes an abrupt increase in temperature at different growth stages of wheat. Thus, wiser selection of stress tolerant varieties is an important strategy to combat the climate change effect. The present study aims for physiological and biochemical screening of timely sown NWPZ wheat varieties (WB2, HD3086, DBW88, DPW621-50, DBW17, HD2967 and PBW550) of India for their thermal stress tolerance along with heat tolerant (RAJ3765) and susceptible checks (RAJ4014) at seedling stage. The experiment was conducted in completely randomized design under controlled laboratory condition and heat stress was induced at 37 °C at seedling stage. Later different physio-biochemical traits were studied in both control and stress seedlings. All traits exhibited significant variations among genotypes under heat stress condition. Root and shoot weight, relative water content, chlorophyll content index and chlorophyll fluorescence reduced significantly, whereas membrane leakage, osmotic potential, catalase, ascorbate peroxidase, guaiacol peroxidase, malondialdehyde content and proline content were increased in stress plants. A tolerance matrix was prepared based on stress response of the genotypes for each trait and a final tolerance score was given to each genotype. Based on this tolerance matrix, DBW88 and PBW550 were identified as tolerant, DPW621-50, DBW17 and HD2967 as moderately susceptible and HD3086 and WB2 as susceptible to heat stress. Earlier studies parade that seedling level stress tolerance has high correlation with adult level stress tolerance under field condition in wheat. Hence, this study helps in wiser selection of varieties for sowing in NWPZ based on weather forecast of the location for creating varietal mosaic in context of climate change.

Influence of silicon and chitosan on growth and physiological attributes of maize in a saline field

Soil salinity is the main constraint for crop productivity in many parts of the world. Application of silicon (Si) and chitosan (Chi) can improve crop growth under saline soil conditions. The current study was aimed to examine the effects of Si and Chi on mitigation of salinity, morphological and physiological attributes as well as the antioxidant system of maize (Zea mays L.) under saline soil conditions. A field experiment was conducted that comprised of nine treatments as follows: (i) Control (no amendment), (ii) Silicon 40 kg ha^-1 (Si1), (iii) Chitosan 15 kg ha^-1 (Chi1), (iv) Si1 + Chi1, (v) Silicon 80 kg ha^-1 (Si2), (vi) Chitosan 30 kg ha^-1 (Chi2), (vii) Si2 + Chi2, (viii) Si1 + Chi2 and (ix) Si2 + Chi1. Application of Si and Chi substantially improved the morphological and physiological attributes as well as antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of maize plants, and combined application of Si and Chi was more effective when compared with Si and Chi treatments separately. Membrane stability index was improved by 25%, relative water content by 26%, chlorophyll a by 69% and b by 56% with combined application of Si and chitosan (Si2 + Chi2) compared with control. The SOD, POD and CAT increased by 36%, 38% and 65% with Si2 + Chi2 compared with control. The results suggest that Si and Chi application is the possible option for alleviating salinity stress in maize plant. Further research is suggested to examine Si and Chi effects on various crop's growth.

Association of molecular markers with physio-biochemical traits related to seed vigour in rice

Eighteen physio-biochemical traits influencing seed vigour were studied for their association with molecular markers using a mini core set constituted from 120 germplasm lines. High genetic variation was detected in the parameters namely chlrophyll a, Chlrophyll b, total chlorophyll, carotenoids, total anthocyanin content, gamma-oryzanols, total phenolics content, superoxide dismutase, catalase, guaicol peroxidase, total soluble sugar, total protein, seed vigour index -I and seed vigour index -II. Strong positive correlation of seed vigour index II was observed with amylose content, total anthocyanin content, catalase, total phenolic content and total flavonoid content while a negative association was observed for gamma-oryzanol content. High gene diversity (0.7169) and informative markers value (0.6789) were estimated from the investigation. Three genetic structure groups were observed in the panel population and genotypes were grouped in the subpopulations based on the seed vigour trait. Differences in the fixation indices of the three sub populations indicated existence of linkage disequilibrium in the studied panel population. Association of the traits namely total flavonoids, superoxide dismutase, catalase, chlorophyll a, Chlorophyll b, total chlorophyll, carotenoids, starch, amylose, total anthocyanin, gamma-oryzanol, total phenolics with the molecular markers were detected by Generalized Linear Model and Mixed Linear Model showing > 0.10 R² value. Association of the trait, total flavonoids with marker RM7364 located on chromosome 8 reported in earlier study was validated in this investigation. The validated markers and the novel markers detected showing higher R² value will be useful for improvement of seed vigour in rice.

Crop nitrogen monitoring: Recent progress and principal developments in the context of imaging spectroscopy missions

Nitrogen (N) is considered as one of the most important plant macronutrients and proper management of N therefore is a pre-requisite for modern agriculture. Continuous satellite-based monitoring of this key plant trait would help to understand individual crop N use efficiency and thus would enable site-specific N management. Since hyperspectral imaging sensors could provide detailed measurements of spectral signatures corresponding to the optical activity of chemical constituents, they have a theoretical advantage over multi-spectral sensing for the detection of crop N. The current study aims to provide a state-of-the-art overview of crop N retrieval methods from hyperspectral data in the agricultural sector and in the context of future satellite imaging spectroscopy missions. Over 400 studies were reviewed for this purpose, identifying those estimating mass-based N (N concentration, N%) and area-based N (N content, N_area) using hyperspectral remote sensing data. Retrieval methods of the 125 studies selected in this review can be grouped into: (1) parametric regression methods, (2) linear nonparametric regression methods or chemometrics, (3) nonlinear nonparametric regression methods or machine learning regression algorithms, (4) physically-based or radiative transfer models (RTM), (5) use of alternative data sources (sun-induced fluorescence, SIF) and (6) hybrid or combined techniques. Whereas in the last decades methods for estimation of N_area and N% from hyperspectral data have been mainly based on simple parametric regression algorithms, such as narrowband vegetation indices, there is an increasing trend of using machine learning, RTM and hybrid techniques. Within plants, N is invested in proteins and chlorophylls stored in the leaf cells, with the proteins being the major nitrogen-containing biochemical constituent. However, in most studies, the relationship between N and chlorophyll content was used to estimate crop N, focusing on the visible-near infrared (VNIR) spectral domains, and thus neglecting protein-related N and reallocation of nitrogen to non-photosynthetic compartments. Therefore, we recommend exploiting the estimation of nitrogen via the proxy of proteins using hyperspectral data and in particular the short-wave infrared (SWIR) spectral domain. We further strongly encourage a standardization of nitrogen terminology, distinguishing between N% and N_area. Moreover, the exploitation of physically-based approaches is highly recommended combined with machine learning regression algorithms, which represents an interesting perspective for future research in view of new spaceborne imaging spectroscopy sensors.

Evaluation of tea (Camellia sinensis L.) biochemical traits in normal and drought stress conditions to identify drought tolerant clones

Abiotic stresses, such as drought, can induce different morphological, physiological and molecular responses in the tea plants. Since there have not been any experiments on the screening of tea genotypes in terms of drought tolerance, this study was conducted to screen the drought resistance of 14 tea clones of Iran germplasm in a randomized complete block design with three replications, separately in two stressed and non-stressed conditions at Fashalam tea station. The results of grouping the clones under normal and stress conditions and comparing their results with the results of mean comparison of the agronomic and biochemical traits showed that in all cases, clones 100, Bazri and 399 were in the group that can be identified as the drought-tolerant group. Also, the results showed that in the most cases, clones 278, 276 and 285 were placed in a group that had low values for all of the traits and could be considered as a group that are susceptible to drought stress.

Deciphering adverse effects of heavy metals on diverse wheat germplasm on irrigation with urban wastewater of mixed municipal-industrial origin

The current study provides one of the first attempts to identify tolerant, moderately sensitive, and highly sensitive wheat genotypes on the basis of heavy metal accumulation, biochemical attributes, and human health risk assessments on urban wastewater (UW) irrigation. Mean heavy metals (Fe, Co, Ni, Cu, Zn, Pb, Cd, Cr, Mn) and macro-nutrients (Na, K, Ca, Mg) levels increased in the roots, stem, and grains of studied genotypes. Except K (stem > root > grain), all metals were accumulated in highest concentrations in roots followed by stem and grains. Principal component analyses (PCA) identified three groups of UW-irrigated genotypes which were confirmed by hierarchical agglomerative cluster analyses (HACA). Wheat genotypes with the lowest metal accumulation were regarded as tolerant, whereas those with maximum accumulation were considered highly sensitive. Tolerant genotypes showed the lowest hazard quotient for heavy metals, i.e., Co, Mn, Cd, Cu, Fe, Pb, and Cr, and hazard index (HI) values (adults, 2.04; children, 2.27) than moderately and highly sensitive genotypes. Higher health risks (HI) associated with moderate (adults 2.26; children 2.53) and highly sensitive (adults 2.52; children 2.82) genotypes revealed maximum uptake of heavy metals. The heatmap showed higher mean biochemical levels of chlorophyll, carotenoids, membrane stability index (MSI%), sugars, proteins, proline, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in tolerant genotypes than remaining genotypes. With the lowest metal accumulation and advanced biochemical mechanisms to cope with the adverse effects of heavy metals in their plant bodies, tolerant genotypes present a better option for cultivation in areas receiving UW or similar type of wastewater.

Impact of lactation stage on milk composition and blood biochemical and hematological parameters of dairy Baladi goats

The objective of this study was to elucidate the impact of lactation stage on milk composition, hematological and biochemical parameters of dairy Baladi goats under Egyptian conditions. Forty-eight Baladi goats (32.8 ± 2.9 kg of BW) were enrolled in the current study. The lactation period has been divided into three stages; early (DIM less than 80 days), Mid (DIM 80-140 days), and Late (DIM over 140 days). Baladi goats had decreased daily-MY at a rate of 18.4% and 31.9% at mid and late stages of lactation, compared with early stage, respectively (p = 0.001). Furthermore, lactose% decreased significantly with progress of lactation (p = 0.017). Total solids%, however, decreased significantly at early stage of lactation in comparison with mid and late stages (p = 0.022). On the contrary, no significant differences were found in protein, fat and SNF percentages at different stages of lactation (p = 0.836, 0.625 and 0.281, respectively). Serum glucose and total protein were significantly reduced at late stage of lactation in comparison with early and mid stages (p = 0.001 and 0.001, respectively). On the contrary, no significant differences were found for erythrocytes count, hemoglobin, serum cholesterol, catalase and triiodothyronine at different stages of lactation. There were high and positive correlations between daily-MY and serum total protein (r = 0.87, P < 0.01) and triiodothyronine (r = 0.41, P < 0.01). However, negative estimates were reported between daily-MY and triglycerides (r = -0.55, P < 0.01) and cholesterol (r = -0.33, P < 0.05). Our results indicate that dairy Baladi goats produce milk with relatively stable protein, fat and solid not fat (SNF) contents at the different stages of lactation, encouraging the continuous utilization of their milk in processing. Also, dairy Baladi goats seem able to maintain the most vital biochemical parameters.