Heterogeneity in Ty1-copia group of retroelements in chickpea (Cicer arietinum) genome

Retrotransposons constitute a major fraction of plant genomes and these elements may have played a significant role in evolution and sequence organization of genomes. In order to access the diversity of Ty1-copia group of retroelements, reverse transcriptase (RT) sequences were amplified from chickpea genome, using the primers derived from two conserved domains of RT region. Thirty-six RT regions from independent amplicons were cloned and sequenced. On the basis of homology of deduced amino acids, the RT sequences could be grouped into three major families. The intra-family divergence at amino acid level ranges from 2 to 19%. Though intra-family RT sequences were conserved but no two sequences were identical. The results indicate a high degree of heterogeneity among the Ty1-copia group of retroelements from chickpea. It was possible to isolate RT specific sequences from RNA isolated from stressed seedlings, indicating that some of the retroelements may be functional under certain stress conditions

Encapsulated somatic embryos of grape (Vitis vinifera L.): An efficient way for storage and propagation of pathogen-free plant material

Cotyledonary-stage somatic embryos (5-7 mm in length) originating from leaf explants of grape (Vitis vinifera L.) cv. Pusa seedless were encapsulated individually in 2 % alginate gel. The encapsulated somatic embryos (ESEs) germinated successfully on 0.7 % agar medium containing B5 macrosalts (half strength), MURASHIGE and SKOOG microsalts (full strength), 3 % sucrose and 2.9 μM gibberellic acid. The percentage of germination of ESEs was higher than that of nonencapsulated somatic embryos (NSEs) of the same size on the same medium. The percent germination of ESEs increased (69.2 ±2.8) on medium supplemented with quarter strength B5 macrosalts. Of the germinating ESEs, 36 % developed into plantlets. Abscisic acid at 0.004 and 0.02 μM had no significant influence on the frequency of germination and plantlet development, however resulted in a 4-week delay in germination. Transferring the embryos onto the full-strength B5 medium containing sucrose and ABA (0.04 μM) for 4-6 weeks prior to encapsulation resulted in extended storage of up to 90 d without loss of the germination potential and the capacity to regenerate into plantlets. Normally developed plantlets regenerated from ESEs were successfully adapted to soil.

Expression of a rice chitinase gene enhances antifungal potential in transgenic grapevine (Vitis vinifera L.)

To enhance the antifungal potential of grapevine, transgenic plants were generated by transferring rice chitinase gene under a maize-ubiquitin promoter along with its first intron into the leaf disc-induced somatic embryos via Agrobacterium mediated transformation. After co-cultivation for 2 days with recombinant Agrobacterium, somatic embryos were transferred onto WPM medium containing BAP 1.5 μM and NAA 0.1 μM supplemented with 25 mg/L hygromycin. Secondary or tertiary embryos were selected and the antibiotic resistant transgenic plantlets were analyzed. The integration and stability of the transgene were confirmed by PCR, RT-PCR, Southern blotting and by Western blot analyses. The transgenic plants exhibited higher chitinase activity than the non-transformed plants. These analyses indicated that the foreign gene was translated into the protein of expected molecular weight that showed chitinase activity. Following in vitro inoculation of powdery mildew (Uncinula necator), the transgenic plants showed delayed onset of the disease and smaller lesions. The transgenic plants were adapted to the greenhouse and did not show any phenotypic alterations.

Automatic weed control system for processing tomatoes

WORLD CONGRESS OF THE INTERNATIONAL COMMISSION OF AGRICULTURAL AND BIOSYSTEMS ENGINEERING (17) (17.2010.QUEBEC CITY, CANADA)This study describes a fully automatic system developed at UC Davis for intra-row mechanical weed control for processing tomatoes in California. We developed a novel weed control system using a real-time kinematics (RTK) global positioning system (GPS) to automatically control the path of a pair of weed knives based upon an automatically generated GPS plant map. The system was capable of precisely guiding mechanical weed knives within the seedline of the crop row and around the crop plants as the system was pulled along the row. In this study, processing tomato plants were transplanted using a GPS-enabled transplanter, which developed a precision plant map documenting the geo-spatial location of each tomato plant. At the time of first cultivation, a few weeks after planting, the GPS-controlled weed knives were operated in seven tomato rows. The weed knives were set to "open" 6 cm prior to reaching, and "close" 6 cm after passing each tomato plant, killing weeds between tomato plants when the knives were in the closed position. Results show that the average distance between knife opening and closing events was 12.4 cm with a standard deviation of 1.4 cm. The standard deviation of the opening and closing positions (relative to the crop plant) was 2.08 and 2.11 cm, respectively. These results demonstrate the feasibility of using RTK-GPS to automatically control a mechanical weed control system for sustainable production of row crops

Development of an RTK GPS plant mapping system for transplanted vegetable crops.

This study investigated the feasibility of using real-time kinematics (RTK) GPS to automatically map the locations of tomato transplants in the field as they are planted using a vegetable crop transplanter retrofitted with an RTK GPS receiver, and an on board real-time controller. Two detection methods were evaluated for sensing plant location during planting. One method used an infrared light beam sensor to detect the stem location of each plant immediately after planting. The second method used an absolute shaft encoder mounted on the planting wheel to sense the location that each plant was placed in the soil. Odometry was used to determine the actual Easting and Northing GPS coordinates of each plant by interpolation from the original RTK GPS data stream. A field test was conducted to compare the accuracy of this transplant map with actual plant location. The average absolute differences between the automatically generated transplant map and the plant location determined by GPS survey was 0.8 to 2.1 cm in the Northing direction and 1.6 to 3.8 cm in the Easting direction, which was also the travel direction. Results suggest the feasibility of creating an accurate plant map using an RTK GPS equipped transplanter

‘DUS’ characterization of an endangered salt tolerant radish landrace (Newar)

In this study, responses to salinity stress of three varieties of radish, viz., ‘Newar’ (landrace), ‘Pusa Mridula’ and ‘White Excel’, were recorded. Additionally, landrace Newar was also characterized for ‘Distinctness, Uniformity and Stability’ (DUS) using 34 descriptors. Results indicated higher salt tolerance in ‘Newar’ as evidenced by relatively early germination and high early seedling vigour than other varieties regardless of the salinity of the irrigation water. Although salinity stress, especially up to 8.0 dS m-1, had no adverse effect on shoot growth in all the varieties, effects on root growth were quite different. While ‘Newar’ exhibited non-significant differences in root fresh weight (RFW) at different salinity levels, ‘White Excel’ displayed nominal variations up to 8.0 dS m-1 salinity and ‘Pusa Mridula’ registered consistent declines in RFW with increasing salinity. ‘Newar’ plants were found to be efficient in Na+ exclusion and in maintaining a favourable Na+ to K+ ratio in their shoots and roots. Further, proline accumulation was much higher in salt treated Newar than in ‘White Excel’ and ‘Pusa Mridula’ plants. Based on DUS descriptors, number of leaves, leaf length, and root length and weight were found to be the major distinguishable characters in Newar

Antisense expression of a gene encoding a calcium-binding protein in transgenic tobacco leads to altered morphology and enhanced chlorophyll

Entamoeba histolytica contains a novel calcium-binding protein like calmodulin, which was discovered earlier, and we have reported the presence of its homologue(s) and a dependent protein kinase in plants. To understand the functions of these in plants, a cDNA encoding a calcium-binding protein isolated from Entamoeba histolytica (EhCaBP) was cloned into vector pBI121 in antisense orientation and transgenic tobacco plants were raised. These plants showed variation in several phenotypic characters, of which two distinct features, more greenness and leaf thickness, were inherited in subsequent generations. The increase in the level of total chlorophyll in different plants ranged from 60% to 70%. There was no major change in chloroplast structure and in the protein level of D1, D2, LHCP and RuBP carboxylase. These morphological changes were not seen in antisense calmodulin transgenic tobacco plants, nor was the calmodulin level altered in EhCaBP antisense plants

Pearl millet germplasm at ICRISAT genebank - status and impact

Pearl millet (Pennisetum glaucum) is an important food and forage crop in Africa and Asia, and forage in Americas. It is probably the world’s hardiest crop and has great potential because of its suitability to the extreme limits of agriculture. It is mainly cultivated in Niger, Nigeria, Burkina Faso, Togo, Ghana, Mali, Senegal, Central African Republic, Cameroon, Sudan, Botswana, Namibia, Zambia, Zimbabwe and South Africa in Africa; and India, Pakistan and Yemen in Asia. The success in crop improvement programs depends largely on the extent of genetic variability available to the researchers. Pearl millet is endowed with enormous genetic variability for various morphological traits, yield components, adaptation and quality traits. In ensuring that the plant breeders will have genetic resources for use in plant breeding programs, collection, conservation, characterization, evaluation, documentation and distribution of plant genetic resources is very important. Large efforts were made to collect and conserve the pearl millet diversity before it is lost forever. In this article, we have summarized the current status of pearl millet germplasm assembled in the genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and discussed its impact

Crossed-Beams and Theoretical Studies of Hyperthermal Reactions of O(\u3csup\u3e3\u3c/sup\u3eP) with HCl†

The reaction of O(3 P) with HCl at hyperthermal collision energies (45-116 kcal mol-1 ) has been investigated with crossed-molecular beams experiments and direct dynamics quasi-classical trajectory calculations. The reaction may proceed by two primary pathways, (1) H-atom abstraction to produce OH and Cl and (2) H-atom elimination to produce H and ClO. The H-atom abstraction reaction follows a stripping mechanism, in which the reagent O atom approaches the HCl molecule at large impact parameters and the OH product is scattered in the forward direction, defined as the initial direction of the reagent O atoms. The H-atom elimination reaction is highly endoergic and requires low-impact-parameter collisions. The excitation function for ClO increases from a threshold near 45 kcal mol-1 to a maximum around 115 kcal mol-1 and then begins to decrease when the ClO product can be formed with sufficient internal energy to undergo secondary dissociation. At collision energies slightly above threshold for H-atom elimination, the ClO product scatters primarily in the backward direction, but as the collision energy increases, the fraction of these products that scatter in the forward and sideways directions increases. The dependence of the angular distribution of ClO on collision energy is a result of the differences in collision geometry. Collisions where the H atom on HCl is oriented away from the incoming reagent O atom lead to backward-scattered ClO and those where the H atom is oriented toward the incoming O atom lead to forward-scattered ClO. The latter trajectories do not follow the minimum energy path and involve larger translational energy release. Therefore, they become dominant at higher collision energies because they lead to lower internal energies and more stable ClO products. The H-atom abstraction and elimination reactions have comparable cross sections for hyperthermal O(3 P) + HCl collisions

Identification of gaps in pearl millet germplasm from East and Southern Africa conserved at the ICRISAT genebank

The International Crops Research Institute for the semi-Arid Tropics Genebank at Patancheru, India holds the world's largest collection of 22,211 pearl millet germplasm accessions from 50 countries including 4488 landraces from 16 East and Southern African (ESA) countries. Gap analysis using FloraMap software and 3750 georeferenced pearl millet germplasm accessions from ESA countries revealed 34 districts located in 18 provinces of four East African countries and 76 districts located in 34 provinces of seven Southern African countries as geographical gaps. Analysis of characterization data using DIVA-GIS software showed 11 districts of seven provinces in Sudan and Uganda and 58 districts of 20 provinces of seven countries in Southern Africa as gaps in diversity for important morphoagronomic traits. The following districts were identified as gaps common to geographic area and diversity for some or the other traits: Amuria district in Soroti province of Uganda; Mpwapwa in Dodoma province of Tanzania; Mahalapye in Centre province and Kgatleng in Kgatleng province of Botswana; Lalomo in Southern province of Zambia; and Motoko, Mudzi and Wedza in the province of Mashonaland East; Makoni in Manikaland; Gutu and Chivi in Masvingo; Gwanda and Bulalimamangwe in Metabeland south; Hwange and Nkayi in Metabeland north; and Kwe Kwe in Midlands of Zimbabwe. For a successful germplasm collection mission to fill the gaps identified, planning should be made in advance of collaboration and consultation with National Agricultural Systems, local government officials and extension officers. It is suggested to collect the complete passport data including georeference information while collecting the germplasm