Root knot and cyst nematodes induce large multinucleated cells, designated giant cells and syncytia, respectively, in plant roots. We have used molecular markers to study cell cycle progression in these specialized feeding cells. In situ hybridization with two cyclin-dependent kinases and two cyclins showed that these genes were induced very early in galls and syncytia and that the feeding cells progressed through the G2 phase. By using cell cycle blockers, DNA synthesis and progression through the G2 phase, or mitosis, were shown to be essential for gall and syncytium establishment. When mitosis was blocked, further gall development was arrested. This result demonstrates that cycles of endoreduplication or other methods of DNA amplification are insufficient to drive giant cell expansion. On the other hand, syncytium development was much less affected by a mitotic block; however, syncytium expansion was inhibited.

Molecular markers and cell cycle inhibitors show the importance of cell cycle progression in nematode-induced galls and syncytia.

Sedentary nematodes are important pests of crop plants. They are biotrophic parasites that can induce the (re)differentiation of either differentiated or undifferentiated plant cells into specialized feeding cells. This (re)differentiation includes the reactivation of the cell cycle in specific plant cells finally resulting in a transfer cell-like feeding site. For growth and development the nematodes fully depend on these cells. The mechanisms underlying the ability of these nematodes to manipulate a plant for its own benefit are unknown. Nematode secretions are thought to play a key role both in plant penetration and feeding cell induction. Research on plant-nematode interactions is hampered by the minute size of cyst and root knot nematodes, their obligatory biotrophic nature and their relatively long life cycle. Recently, insights into cell cycle control in Arabidopsis thaliana in combination with reporter gene technologies showed the differential activation of cell cycle gene promoters upon infection with cyst or root knot nematodes. In this review, we integrate the current views of plant cell fate manipulation by these sedentary nematodes and made an inventory of possible links between cell cycle activation and local, nematode-induced changes in auxin levels.

Cell cycle activation by plant parasitic nematodes.

Nymphaea stellata Willd. (Syn. Nymphaea nouchali Burman f.) (Nymphaeaceae) is an important and well-known medicinal plant, widely used in the Ayurveda and Siddha systems of medicines for the treatment of diabetes, inflammation, liver disorders, urinary disorders, menorrhagia, blenorrhagia, menstruation problem, as an aphrodisiac, and as a bitter tonic. There seems to be an agreement between the traditional use and experimental observations, such as, hepatoprotective, anti-inflammatory, and particularly antidiabetic activity. Nymphayol, a steroid isolated from the flowers has been scientifically proved to be responsible for the traditionally claimed antidiabetic activity; it reverses the damaged endocrine tissue and stimulates secretion of insulin in the β-cells. However, taking into account the magnitude of its traditional uses, the studies conducted are still negligible. This review is an attempt to provide the pharmaceutical prospective of Nymphaea stellata.

/pdf/a-comprehensive-review-on-nymphaea-stellata-a-traditionally-3y92gi18qg.pdf

A comprehensive review on Nymphaea stellata: A traditionally used bitter.

Question: How resilient is the seed bank of an invaded dune system? Is that resilience dependent on duration of invasion? How does the accumulated litter layer contribute to the soil seed bank?



Location: Coastal sand dunes invaded by Acacia longifolia, Portugal.



Methods: Seedling emergence was used to quantify and compare soil seed banks in long-invaded, recently invaded and non-invaded areas. Changes in seed banks were also compared with areas where A. longifolia and the litter layer were removed.



Results: Species richness, seedling density and diversity were higher in non-invaded and recently-invaded areas than in long-invaded areas. Although there was an apparent similarity between non-invaded and recently-invaded areas, analyses of species traits revealed differences. Non-invaded areas had a wider array of traits. Exotic/invasive species dominated invaded seed banks while native species dominated non-invaded seed banks. Life forms, growth forms, longevity and dispersal mode showed differences between areas, with cleared plots of long-invaded areas being apparently the most similar to non-invaded plots. Acacia longifolia seeds were most abundant in long-invaded areas, particularly where the litter layer remained. Removal of A. longifolia plus the litter had little effect on the seed bank composition of recently-invaded areas but resulted in noticeable changes in seed banks of long-invaded areas.



Conclusions: Long-invaded areas are less resilient and show a higher reinvasion potential, despite severe alteration of the seed banks of both areas. Seed bank studies can be a useful tool to guide management, but can give misleading results when invasion periods are protracted.

The potential role of seed banks in the recovery of dune ecosystems after removal of invasive plant species.

Statistical yearbook of Bangladesh = Bāṃlādeśa parisaṃkhyāna barshagrantha

SUMMARY: The experiment was carried out to ascertain the effects of age on wheat and barley seeds. Germination percentage of different years old wheat and barley seeds were found to decrease gradually with an increase of the storage time. The germination percentages of wheat seeds were much lower than that of barley seeds. Mitotic index and chromosomal irregularities from root tip cells were also studied. Most of the irregularities were characterized by precocious separation of chromosomes and inactivation of spindle mechanism, chromosome fragment, laggard, bridge, condensed and sticky chromosome, ring chromosomes etc. In both the materials, the frequencies of dividing cells were found to decrease with the increase of the age of seeds. Frequency of abnormal cells were also found to increase with the increase of the age of seeds. The frequency of chromosomal aberrations with increased storage time was closely related to the loss of germinability.

Aging effect of wheat and barley seeds upon germination mitotic index and chromosomal damage

Laboratory studies were conducted with leaf powder of three plants to show the preservative effect for maintaining the quality of lentil seeds in storage. After processing and drying, seeds were preserved with different botanicals and stored them in earthen pots for eight months. Botanicals, such as whole leaf powder of neem (Azadirachta indica), dholkalmi (Ipmoea sepiara), and bishkatali (Polygonum hydropiper) were used at a dose of 5% w/w (25 g botanical per 500 g of lentil seeds). The lentil seeds were stored till next planting time and seed quality, such as moisture content, germination capacity, root length, shoot length of the seedlings and vigour index were observed. The highest values for all these characters except moisture content were significant when the seeds were preserved with neem leaf powder and bishkatali. Among three botanicals, dholkalmi was less effective. Keywords: Lentil; botanicals; storage; seed quality DOI: http://dx.doi.org/10.3329/bjar.v36i3.9266 BJAR 2011; 36(3): 381-387

/pdf/effect-of-preserved-seeds-using-different-botanicals-on-seed-1ymuvp4lf1.pdf

Effect Of Preserved Seeds Using Different Botanicals On Seed Quality Of Lentil

This study shows that enhancement of soil fertility along with the yield of chickpea due to nodulation by the Rhizobium is possible to some extent. Data on plant height (cm) at maturity, primary branches/plant, days to flower, pods/plant, pod dry weight/plant (g), seeds/pod, seed dry weight/pod (g), 50 seeds weight (g), nodules/plant, fresh weight of nodules/plant and dry weight of nodules/plant were considered to assess the effect of nodulation in chickpea. Soils treated with Rhizobium always showed higher values than control regarding total nitrogen and organic matter (%). Campus soil showed the highest value for organic matter (%) and N content but Cholonbil soil exhibited the highest value for number of seeds per pod. All the parameters for growth analysis yielded greater values for treated soils compared to that of the control. DOI: http://dx.doi.org/10.3329/jles.v6i0.9720 JLES 2011 6: 45-50

/pdf/effect-of-rhizobium-inoculant-on-nodulation-yield-and-yield-4xty0l18ye.pdf

Effect Of Rhizobium Inoculant On Nodulation, Yield And Yield Traits Of Chickpea ( Cicer Arietinum L.) In Four Different Soils Of Greater Rajshahi

Mitotic effect of leaf extracts of Ipomoea carnea on Allium cepa.

Interphase nuclear organization was studied in six species of Cicer and all the species showed chromocentric nuclear organization in both meristematic and differentiated cells instead of reticulate organization. The number of chromocentres and treatment duration with acid or alkali were found to be species specific character. Percentage heterochromatin values determined by two different techniques were somewhat high in meristematic cells than those in differentiated cells. On the basis of heterochromatin values both in meristematic and differentiated cells C. reticulaturn can be considered as primitive of the six Cicer species. Nuclear organization was found to be governed by small size of chromosomes and low DNA content, but the relationship between heterochromatin values and DNA content was not clear.

https://www.jstage.jst.go.jp/article/cytologia1929/54/1/54_1_27/_pdf

G Kabir

Papers

Aging effect of wheat and barley seeds upon germination mitotic index and chromosomal damage

Effect Of Preserved Seeds Using Different Botanicals On Seed Quality Of Lentil

Effect Of Rhizobium Inoculant On Nodulation, Yield And Yield Traits Of Chickpea ( Cicer Arietinum L.) In Four Different Soils Of Greater Rajshahi

Mitotic effect of leaf extracts of Ipomoea carnea on Allium cepa.

Interphase nuclear structure and heterochromatin in Cicer species