Piriformospora indica suppresses the symptoms produced by Banana bract mosaic virus by inhibiting its replication and manipulating chlorophyll and carotenoid biosynthesis and degradation in banana.

Banana bract mosaic virus (BBrMV) infection results in characteristic reddish streaks on pseudostem and chlorotic spindle lesions on leaves leading to traveler's palm appearance and complete crop loss depending on the stage of infection in banana plants. Here, we discuss the influence of P. indica colonization (a beneficial fungal root endophyte) on BBrMV infection, specific viral component genes responsible for symptom development, chlorophyll and carotenoid biosynthesis, and degradation in BBrMV-infected banana plants. P. indica colonization significantly and substantially reduced the severity of Banana bract mosaic disease (BBrMD) in addition to increased growth, development and yield of banana plants. The percent disease incidence (PDI) of BBrMV ranges from 50 to 70 per cent in plants raised from suckers and from 58 to 92 per cent in TC plants under artificial inoculation. P. indica-colonized plants inoculated with BBrMV resulted in an enhanced plant height, root length, leaf width, and leaf length of 72, 88, 90, and 60 per cent, respectively, compared to BBrMV alone-infected banana plants along with the reduced disease severity. BBrMV infection showed a drastic decrease of chlorophyll a, chlorophyll b, and total chlorophyll contents by down-regulating chlorophyll biosynthesis (Chlorophyll synthase-CHLG) and upregulating chlorophyll degradation (Chlorophyllase-CLH1 and CLH2 and Pheophytin pheophorbide hydrolase-PPH) genes; and by up-regulating carotenoids biosynthesis (Phytoene synthases-PSY1 and PSY2) and down-regulating its degradation (Phytoene desaturase-PDS) genes compared to P. indica-colonized banana plants challenge inoculated with BBrMV. P. indica also inhibited the expression of the viral genes (P3 and HC-Pro) involved in symptom development. P. indica-colonized banana plants reduced the BBrMV symptoms severity by enhancing chlorophyll biosynthesis; and decreasing chlorophyll degradation and carotenoid biosynthesis and degradation; and inhibiting the viral genes responsible for symptom development in addition to enhanced growth and yield of banana plants. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-024-03983-y.

Nano-PCR for the early detection of tomato leaf curl virus.

Nano-PCR is a potential tool for the early detection of plant viruses. In the current study, different concentrations of silver nanoparticles (20 nm) and magnesium oxide nanoparticles (50 nm) were included in the PCR mixture to improve the sensitivity of PCR for the detection of tomato leaf curl virus. The inclusion of nanoparticles in single or combination in PCR mixture has resulted in improvement of PCR sensitivity. Four-fold improvement was exhibited by the inclusion of 3 ng/µL silver nanoparticles, whereas the combination of silver and magnesium oxide nanoparticles (3 ng/µL and 200 ng/µL, respectively), resulted in a 4.5-fold improvement. The inclusion of 200 ng/µL of magnesium oxide nanoparticles in the PCR mixture exhibited a 7.6-fold increase in PCR sensitivity. Replacement of magnesium chloride with a combination of silver and magnesium oxide nanoparticles (3 ng/µL and 275 ng/µL, respectively) resulted in a 12-fold increase. A 13-fold improvement in PCR sensitivity was observed by the replacement of magnesium chloride in PCR buffer with 275 ng/µL of magnesium oxide nanoparticles. This could also produce detectable amplicon in PCR with a minimum of 25 cycles, resulting in a 26.5% reduction in the duration of PCR. This is the first report on the use of magnesium oxide nanoparticles in PCR for the early detection and better management of tomato leaf curl virus. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03842-2.

Impact of biofertilisers on iron homeostasis and grain quality in the rice variety Uma under Elevated CO2.

The diminishing nutritional quality of rice with increasing concentrations of atmospheric CO2 is currently a major global concern. The present study was designed with the objective of assessing the impact of biofertilisers on grain quality and iron homeostasis in rice under elevated CO2. A completely randomised design with four treatments ([KAU, POP (control), POP+Azolla, POP+PGPR, and POP+AMF]), each replicated three times under ambient and elevated CO2 conditions, was followed. The analysed data revealed that yield, grain quality, and iron uptake and translocation were modified in an unfavourable manner under elevated CO2, which was reflected in the lower quality and iron content of the grains. The response of iron homeostasis in the experimental plants to the application of biofertilisers, especially plant-growth-promoting rhizobacteria (PGPR), under elevated CO2 strongly suggests the possibility of utilising them for designing iron management strategies for achieving higher quality in rice.

High temperature induced changes in quality and yield parameters of tomato (Solanum lycopersicum L.) and similarity coefficients among genotypes using SSR markers.

High temperature induced by climatic fluctuations are an important threat for plant growth, development and quality of agricultural produces. Adaptableness to environmental changes generally derives from a large set of genetic traits affecting physio-morphological, biochemical and agronomic parameters. Therefore, the identification of genotypes with higher yield and good quality parameters at high temperatures is becoming increasingly necessary for future breeding programs. Here, we analyzed the performance of different tomato genotypes grown under elevated temperatures in terms of yield and nutritional quality of the fruit. High temperature stress was induced from flower initiation to maturity stage by keeping the pots in a temperature controlled green house facility for 45 days. The quality and yield parameters were taken at the harvesting stage. Starch and soluble sugar concentration in the leaves of tomato genotypes showed significant reduction in its amount under heat stress. Titrable acidity (TA), total soluble solids (TSS) and ascorbic acid content of tomato fruits were highest under high temperature conditions compared to ambient condition but lycopene content decreased with rise in temperature. The yield attributes viz., number of fruits/plant, fruit set %, average fruit weight (g), yield per plant (g/plant) were significantly lower for Arka Saurabh, Arka Rakshak and Pusa Rohini when compared to other genotypes under study. Molecular characterization of selected 22 tomato genotypes were assessed using 25 simple sequence repeat (SSR) markers. Phylogenetic tree was constructed by the unweighted neighbour-joining method (UPGMA) using NTSYSpc cluster analysis software. The Jaccard's similarity matrix was constructed using the SIMQUAL method using UPGMA algorithm in NTSYSpc. Jaccard's similarity matrix among these tomato genotypes ranged from a minimum of 0.22 to a maximum of 1 with an average genetic similarity of 0.67. Hence this study has importance in identifying genotypes that could maintain good quality and higher yield under high temperature condition.

Water stress mediated root trait dynamics and identification of microsatellite markers associated with root traits in rice (Oryza sativa L.).

To identify microsatellite markers associated with root traits for drought tolerance in rice (Oryza sativa L.) a study was conducted at Department of Plant Physiology, College of Agriculture, Trivandrum, Kerala Agricultural University. A set of thirty-five rice genotypes were exposed to water stress and evaluated for physio-morphological components as indices of water stress tolerance. Observations were made on leaf rolling score and root traits, especially the root length, root dry weight, root volume and root shoot ratio at booting stage. As of the data obtained, ten tolerant and ten susceptible varieties were selected for bulk line analysis to identify the DNA markers linked with target gene conferring drought tolerance. Out of 150 SSR primers screened, RM474 showed polymorphism between the tolerant and susceptible bulks. Individual genotypes of the bulks also showed the same product size of the respective tolerant and susceptible bulks.

Cytokinin oxidase activity and cytokinin content in roots of sunflower under water stress.

Contents of trans-zeatin riboside (ZR), dihydrozeatin riboside (DZR) and N6-(delta2-isopentenyl) adenosine (iPA) was quantified by an indirect ELISA using polyclonal antibodies, in the roots, xylem sap and leaves of pot grown sunflower plants subjected to water stress (RWC of leaves approximately 65 per cent). The delivery rates of all three cytokinins decreased significantly under stress. Cytokinin levels also decreased in roots and in leaves of stressed plants. Three-fold increase in cytokinin oxidase activity was observed in stressed roots after polymin P-ammonium sulphate fractionation. Further purification using Con A agarose resulted in elution of protein with cytokinin oxidase activity and was found to be 30 kDa protein on SDS-PAGE.

Unusual discrimination against carrier protein antibodies during partial purification of hapten-protein polyclonal antibodies to plant stress hormones.

Polyclonal antibodies (PcAb) were raised against t-zeatin riboside (t-ZR) and abscisic acid (ABA). t-ZR-BSA and ABA-BSA antibodies had high titre and specificity to haptens but also contained BSA specific antibodies as observed in double immuno diffusion and quantitative precipitation tests. Partial purification of antiserum by precipitation, desalting, and ion-exchange chromatography almost completely eliminated interference from BSA specific antibodies. Consequently, very little or no reaction was observed in dot-immunoblot assays even when high concentrations of BSA were probed with partially purified t-ZR-BSA IgG. Further studies with ABA antiserum showed that discrimination against BSA occurred during chromatography and not during salt fractionation. Because antibodies to both hapten and carrier protein were predominantly of IgG class, this unusual discrimination against carrier protein Ab was possibly influenced by two approaches followed for DEAE chromatography, viz. (i) adsorption of IgG at pH 8 followed by elution; or (ii) adsorption of contaminating proteins at neutral pH while specific IgG comes off as unbound fraction.