Molecular differentiation in Indian Citrus L. (Rutaceae) inferred from nrDNA ITS sequence analysis

Molecular differentiation in 24 accessions representing 19 taxa of Indian Citrus has been examined through sequence analysis of Internal Transcribed Spacer (ITS) region of nrDNA. Sequence length in the 24 accessions of Citrus taxa ranged from 512 to 665 bp (ITS1 & ITS2 partial and 5.8S complete sequence). The ITS sequences were very rich in G+C content ranging from 61.40 to 66.60% with an average of 64.2%. Genetic distance within Citrus group ranged from 0 to 13.4% with an average of 4.6%, showing moderate rate of nucleotide divergence. The phylogeny was inferred using the Maximum parsimony (MP) and Neighbor-Joining (NJ) methods. Both MP and NJ trees separated all the 24 accessions of Citrus into six distinct clusters. The disposition of all the accessions of Citrus in separate clusters in ITS-derived dendrograms was partly in accordance with the morpho-taxonomic affinities of the target taxa. This study supports the concept of Citrus medica (citron), C. reticulata (mandarin), and C. maxima (pummelo) as the basic species of the genus. However, ITS marker could not find any clear cut differentiation between subgenera Citrus and Papeda as proposed in Swingle’s Citrus classification system. The present study also supports the distinctiveness of C. indica (Indian wild orange), C. latipes (Khasi papeda) and C. hystrix (Melanesian papeda) as true species, besides elucidating the probable hybrid origin and relationships among the cultivated species/biotypes, such as Citrus ×aurantiifolia (sour lime) C. ×limon (lemon), C. ×taitensis (Indian rough lemon), C. limettioides (sweet lime), C. ×aurantium (including sour and sweet oranges and grapefruit), and other indigenous varieties of Indian origin: C. megaloxycarpa (sour pummelo), C. karna (karna orange), C. pseudolimon (Hill lemon), ‘Memang athur’, ‘Pummelo-lemon’ and ‘Kathairi nimbu’.     

ISSR polymorphism in Indian wild orange (Citrus indica Tanaka,Rutaceae) and related wild species in North-east India

Inter simple sequence repeats (ISSR) polymorphism in Citrus indica Tanaka (Rutaceae), an endemic and threatened wild species, was examined along with three other closely related wild taxa (C. medica L., C. latipes (Swingle) Tanaka, and C. sp. ‘Memang athur’) by analyzing 53 representative accessions sampled from North-east India. Jaccard's similarity values among 53 accessions of Citrus ranged from 0.46 to 0.97 (average = 0.75). Genetic similarity values among all the 34 accessions of C. indica were found in the range of 0.82 to 0.97 with an average of 0.90. Heterozygosity (Ht = 0.123) and Shannon's information index (I = 0.188) values estimated for C. indica revealed significantly low level of genetic variation within the species. UPGMA dendrogram grouped all 53 accessions of Citrus into four major clusters: Cluster I – C. latipes; Cluster II – C. medica; Cluster III – ‘Memang athur’ and Cluster IV – C. indica. The dendrogram placed all the 34 accessions of C. indica in five sub-clusters under Cluster IV. The placement of C. indica accessions in various sub-clusters and groups in the dendrogram was based on molecular differentiation of individual accessions rather than their geographical origin. Very low genetic diversity and destruction of its natural habitat pose serious threat to C. indica even in the Citrus Gene Sanctuary in Nokrek Biosphere Reserve (NBR) in Meghalaya. Low genetic variability, heterozygosity and Shannon's information index in C. medica, C. latipes and ‘Memang athur’ are also concerns that need to be addressed for developing appropriate strategies to conserve the genetic diversity extant in these valuable genetic resources.     

Sarcophine-Diol Inhibits Expression of COX-2, Inhibits Activity of cPLA2, Enhances Degradation of PLA2 and PLC��1 and Inhibits Cell Membrane Permeability in Mouse Melanoma B16F10 Cells

Sarcophine-diol (SD) is a semi-synthetic derivative of sarcophine with a significant chemopreventive effect against non-melanoma skin cancer both in vitro and in vivo. Recently, we have studied the effect of SD on melanoma development using the mouse melanoma B₁₆F₁₀ cell line. In this study, our findings show that SD suppresses cell multiplication and diminishes membrane permeability for ethidium bromide (EB), a model marker used to measure cell permeability for Ca²⁺ ions. SD also decreases protein levels of COX-2, and increases degradation of phospholipases PLA₂ and PLC_γ1 and diminishes enzymatic activity of the Ca²⁺-dependent cPLA₂. This lower membrane permeability for Ca²⁺-ions, associated with SD, is most likely due to the diminished content of lysophosphosphatidylcholine (lysoPC) within cell membranes caused by the effect of SD on PLA₂. The decrease in diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP₃) due to inhibition of PLC_γ1, leads to the downregulation of Ca²⁺-dependent processes within the cell and also inhibits the formation of tumors. These findings support our previous data suggesting that SD may have significant potential in the treatment of melanoma.     

Effect of zinc application methods on apparent utilization efficiency of zinc and potassium fertilizers under rice-wheat rotation

Apparent utilization of zinc (Zn) and potassium (K) fertilizers was examined in rice (Oryza sativa L.)-wheat (Triticum aestivum L.) using combinations of no K; soil applied K levels and no Zn; soil and foliar applied Zn. Application of 33.2 kg K ha^?1 in rice and 24.9 kg K ha^?1 in wheat along with foliar spray of 2 kg Zn ha^?1 at 30 and 60 days gave the highest mean grain yields. Foliar application of zinc increased Zn concentration in flag leaves, grain, and straw of rice and wheat and K concentration in flag leaves of rice and straw of wheat significantly. Potassium application increased Zn concentration in rice grain and straw and K concentration in wheat straw significantly. Zinc and K increased the uptake of each other in grain; straw and total uptake by both crops significantly. Zinc fertilizer enhanced the utilization of soil K. Potassium fertilizer enhanced the utilization of applied Zn.     

Naturally occurring auxins and inhibitor and their role in fruit growth and drop of mango ‘Dashehari’

The pattern of fruit growth in mango ‘Dashehari’ (Mangifera indica L.) was sigmoid. Pollinated ovaries and young fruits dropped in two main waves: 0–14 days and 28–35 days. A third wave, a mild one, was continuous and irregular from 35 days after pollination to maturity of the fruit.One acidic and one non-acidic auxin and one acidic inhibitor were detected in the immature fruit. The increase in the levels of auxin corresponded with a period of rapid fruit growth, while high levels of inhibitor tended to correspond with a high rate of fruit drop from pollination to 42 days. The auxins appear to play a major role in the growth of the fruit, whereas the inhibitor appears to cause fruit drop.     

Identification of genomic locations associated with grain micronutrients (iron and zinc) in rice (Oryza sativa L.)

Genetic Resources and Crop Evolution - In this investigation, recombinant inbred lines (RILs) population derived from PAU 201 (high yielding) and Palman 579 (high iron and zinc content) varieties...     

Inland saline aquaculture increased carbon accumulation rate and stability in pond sediments under semi-arid climate

Purpose

Similar to fresh- and brackish water aquaculture ponds, commercial shrimp farming in degraded saline areas holds the potential to bury carbon (C) in the sediments. However, studies on the mechanisms of sediment C dynamics and C-flux in response to inland saline aquaculture management practices are still scarce. Therefore, the objectives of the present study are to quantify the C burial rate in inland saline aquaculture ponds and assess the impact of inland saline aquaculture on sensitive C fractions in the bottom sediment of the ponds.

Materials and methods

The sediment samples (n?=?12 from each pond) were collected from six shrimp farming ponds (1000 m² area of each pond) of different ages. The sediment depth, sediment accumulation rate and the levels of total carbon (TC), total organic carbon (TOC) and sediment oxidizable organic carbon (SOC) and its different fractions were determined using standard procedures. The data were analysed by one-way analysis of variance (ANOVA), followed by the Duncan's multiple range test for comparing the means, and the Pearson correlation test was used to assess the relationship between the different pond sediment parameters and SOC content.

Results and discussion

The results revealed that the annual C accumulation rates varied from 902 to 1346 kg C ha^?1 year^?1 in 7-year-old earthen ponds (EPs) and bottom cemented ponds (BCPs), respectively. The sediment C fractions, including TC, TOC, SOC and its fractions (very labile, VLc; labile, Lc; less labile, LLc), and non-labile carbon (NLc)) were progressively increased over the pond age. The inland saline aquaculture practices over the years increased both active (AC) and passive carbon (PC) pools in the pond sediments, helped in the restoration and improvement of sediment quality and enhanced C sequestration potential of the sediments. Furthermore, a significant increase in the level of particulate organic carbon (POC) in BCPs justified that the non-ploughing practices at BCPs facilitated the formation of macro- and micro-aggregates, thereby increasing the C retention and stability of the pond sediments.

Conclusion

This study suggested that the shrimp farming ponds in semi-arid saline soils represented considerable C burial hotspots, enhanced the stable passive C pools and improved the sediment quality.

     

Molecular identification of a Candidatus phytoplasma (Group16SrV-D) coding partial uvrB gene and degV gene on a new host – mesta (Hibiscus sabdariffa) – with phyllody and reddening of leaves in India

Mesta (Hibiscus sabdariffa) is an important bast fiber crop. In August 2011, there was an outbreak of a phytoplasma-like disease on H. sabdariffa in different villages of the northern coastal mesta-growing region of Andhra Pradesh, India, covering mainly two districts – Srikakulam and Vijayanagaram. The infected plants showed characteristic symptoms such as phyllody and reddening of leaves. PCR with P1/P7 universal primer pair of 16 S rDNA yielded amplicons of 1850 bp from all symptomatic mesta leaf samples similar to samples of brinjal little leaf (phytoplasma positive reference control). However, asymptomatic samples were not amplified. Multiplex nested-PCR showed simultaneous amplification of DNA fragments with phytoplasma specific primers, viz., P1/P7 universal primer pair of 16 S rDNA, nested primer pair R16F2n/R2, uvrB and DegV gene-specific uvrB-degVF/R primer generating amplicons of 1850 bp, 1200 bp and 1023bp, respectively. However, SecY-map gene specific primer SecY-mapF/R was not amplified. The 1023 bp nucleotide sequence of uvrB and DegV gene of the phytoplasma was deposited in the GenBank (NCBI) with the accession no. JX975061. NCBI BLASTn analysis of the 1023 bp products showed that the phytoplasma strain belonged to elm yellows group (16SrV-D). This is the first report that Hibiscus sabdariffa is infected by a phytoplasma and we named it mesta phyllody disease (MPD).     

Insecticidal properties of Mentha species: A review

In view of the environmental, food-safety and health related issues associated with the application of chemical insecticides, growing emphasis is being laid on insect-pest control through plant resources. Mentha (mint) is one of the most common herb which has been known for its medicinal and aromotherapeutic properties since ancient times and in the last few decades, its insecticidal potential has also been investigated. The present review consolidates studies concerning insecticidal activity of Mentha against various stored grain pests and vectors. Insecticidal properties of different Mentha species are commonly inherent in its essential oils or plant extracts which is correlated with their chemical composition. Insect/pest control potential of various Mentha species has been evaluated by conducting adulticidal, larvicidal and growth/reproduction inhibition bioassays. Fumigant and repellent activity of Mentha essential oil has been studied against several stored grain pests (Tribolium castaneum, Sitophilus oryzae, Acanthoscelides obtectus, etc.) and vectors. Nevertheless, studies exploring larvicidal and growth/reproduction regulatory activity of Mentha, are relatively less. Among the vectors, mosquitocidal activity of several Mentha essential oils and their constituents is established. However, the studies directed towards formulation or product development and performance assessment in actual field conditions are lacking. Hence, although a ground has been set based on the lab scale research investigations, field studies on these aspects are warranted to ensure wide scale application.