Annual Research & Review in Biology

The extraction of high-quality DNA from cassava leaves suitable for various molecular techniques is a challenge due to the presence of polysaccharides, proteins and polyphenols that interfere with the isolation procedures and downstream applications. This article describes a rapid and efficient procedure for isolating high yield and quality DNA from cassava leaves of six different cultivars (Kibandameno, Seveu, Mkombozi, TMS60444, TME14 and TME419). Improvement on the quantity and quality of the extracted DNA was achieved through modification of cetyl trimethylammonium bromide (CTAB) DNA extraction procedure. The modifications included addition of 20% sodium dodecyl sulfate (SDS) and 4% polyvinylpyrrolidone (PVP), use of increased concentration of ethylenediaminetetraaceticacid (EDTA) and exclusion of liquid nitrogen. The quantity and quality of extracted DNA was assessed using a spectrophotometer and agarose gel electrophoresis. The modified method in this study yielded an average amount of 2400.5 - 2919.8 ng/μl per 100 mg of leaf materials with UV absorbance ratios A260/280 of 1.81 - 1.85. Agarose gel electrophoresis (1%) illustrated intact, sharp and clear bands without degradation. The isolated DNA with this protocol served as a robust template for PCR based downstream applications of simple sequence repeats (SSR) and virus detection.

The results presented in this study demonstrate the suitability of CTAB-SDS method in yielding high quality DNA from cassava leaves suitable for downstream molecular biology techniques.

Aims: The present investigation aimed at in vitro establishment, multiplication and regeneration of plantlets from tomato callus using leaf, internode and root explants from in vitro geminated seedlings of cv. Solan Vajr.

Study Design: Completely randomized design (CRD).

Place and Duration of Study: Department of Biotechnology, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India -173230, between 2013 and July 2015.

Methodology: Murashige and Skoog (MS) medium given in 1962 was used to carry out tissue culture experiments. Seeds of Tomato cv. Solan Vajr were sterilized using bavistin and sodium hypochlorite before proceeding for germination. Different concentrations of 6- Benzylaminopurine (BAP) and Naphthalene acetic acid (NAA) were tried for callus establishment, multiplication and regeneration.

Results: Treatment of leaf explant with 0.1% (w/v) bavistin for ten minutes and 0.5% (v/v) sodium hypochlorite for three minutes was the most effective giving 68.05% uncontaminated cultures and 60.94% survival of seedlings. MS medium supplemented with 1.2 mg/l GA₃ gave the optimum seedling germination of 32.33%. MS medium supplemented with 3.0 mg/l NAA+ 1.0 mg/l BAP gave maximum growth of callus. Leaf and root explants gave 95.21% and 81.11% callus induction than internode (100%). The medium found best for callus growth was also found most suitable for callus multiplication and regeneration.

Conclusion: This study standardized protocols for callus initiation from different types of explants. Internode was found the best explant for callus induction in tomato cv. Solan Vajr. Protocol was also successfully established for multiplication, maintenance and regeneration from callus. This in vitro generated callus can further be used for cell selection studies.

The present study was aimed to document the anatomy of the hind limb skeleton from a structural and functional perspective for the better understanding of locomotor behavior of the orange rumped agouti (Dasyprocta leporina), a caviomorph rodent on the verge of domestication in Trinidad and Tobago. The study was carried out by collecting bones from 6 adult male and 6 adult female animals. The results showed that several features were indicative of emphasized parasagittal movements and stabilized joints. The well-developed ischial tuber, long and strongly built ilium with wide wing and close grouping of greater and lesser trochanter near the proximal tuberosity of the femur imply that the animal possesses a well developed flexor-extensor muscle set adapted to quick movements (reaction). The rather elongated body of the calcaneus strengthened the good jumping ability of D. leporina. These features along with elongation of the shank and foot indicate that D. leporina exhibits a well-developed cursorial ability with high jumping potential.

A two-year data set of Periwinkle (Tympanotonous fuscatus) population from a deforested mangrove area was used to assess its population dynamics. Periwinkle snail samples in one hundred (100) 1 m² quadrats were collected, each in 2015 and 2016. The summary statistics of the periwinkle population show a mean density of 21 indv/m² in 2015 and 12 indv/m² in 2016. The length parameter ranged from 0.9 cm-3.6 cm (mean 2.00±0.33) in 2015 and 1.4 cm-5.1 cm (mean 1.76±0.43) in 2016 while the weight parameter ranged from 1.5 g-5 g (mean 1.50±1.51) and 0.4 g-2.53 g (mean 0.70±0.48). The population density indicated a significant change between 2015 and 2016. The total abundance of periwinkle snails between the years declined by forty (40%) percent, varying from a density of 2090 snails in 2015 to 1192 snails in 2016. The distribution statistics also showed that the likelihood of obtaining seven (7) snails in 2016 collections with 1 m² quadrats declined by 10%; and 18 and 29 snails by sixty-five (65%) percent. The significant difference in abundance values using the Student’s t variance estimate (p<0.05) was also observed (p<0.05) for the variance estimates of the length and weight categories. In the length category, evidence of significant change was indicated by the decline in obtaining the class interval of 1.2 cm-1.6 cm by ten (10%) percent in 2016 collections. Further evidence of significant change in population characteristic was also observed in the weight parameter where the weight class 3 g to 5.5 g was absent in the 2016 collections. The relationship between length-weight was non-collinear in 2015 year collections with a very low R² = 0.007, indicating that the contribution of shell length to body weight can only be predicted by 0.3%. In contrast, in the 2016 collections, the length-weight relationship returned a value of R² = 0.646971 indicating that the contribution of the shell length to body weight can be predicted by sixty percent (60%). These differences in population characteristics were interpreted as evidence of the snail response to interplay of environmental conditions between the dates of collection which were similar. Harvesting pressure and indiscriminate habitat destruction are noted as extreme drivers that can likely overwhelm the natural balance of ecological factors. Although the influences of habitat conditioning factors were not discussed, evidence of the quantitative variation in the population dynamics is given to direct future research in conservation.

Wheat (Triticum spp) is a crop of global significance and occupies a premier place among cereals. Due to its high nutritive value and huge acreage devoted for cultivation of wheat, it is a staple food supplying approximately 20% of total food calories. Although wheat has a wide range of climatic adaptability, it is usually affected by many biotic factors the most devastating of which are the rust diseases. All the three species of rusts viz. stem (black) rust (Puccinia gramims); leaf (brown) rust (P. triticina) and stripe (yellow) rust (P. striiformis) infect wheat crop. Yellow and leaf rusts cause enormous reduction in grain weight and yield. Both usually occurs in cooler areas when temperature ranges between 10-21°C. Different rust races are evolving and a total of 49 races of leaf rust and 22 of stripe rust identified. The wheat cultivars become susceptible to rusts due to their narrow genetic base and the rapid rate of evolution of the pathogen.  In order to sustain wheat production, use of disease resistant varieties is economical and efficient with resource poor farmers. The Indian wheat breeding programmes have also designated 49 and 67 genes for resistance to stripe and leaf rusts of wheat. Rust resistance genes most prevalent in Indian wheat varieties are Lr1, Lr3, Lr10, Lr13, Lr19, Lr23, Lr24, Lr26, Lr28, Lr34 for leaf rust, YrA, Yr2, Yr9, Yr18, Yr 27 for stripe rust. So the ultimate objective of the wheat breeding is to have improved better yielding, resistant cultivars with combined resistance through pyramiding especially those Lr/Yr genes which act against important races of leaf and yellow rusts.