CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Scanning electron microscopic studies on the head appendages and its sensory structures of an immature stage of Spilarctia obliqua (Wlk.) (Lepidoptera Arctiidae) – a pest of mulberry (Morus sp.).
Get PDFThe mouthparts and antennae of the second and third instar larvae of Spilosoma obliqua Wlk., were studied using scanning electron microscope. The three segmented antenna bears sensory structures which are olfactory in function. The labrum and mandibles are also parts of the mouthparts and have their own function in selection and intake of food. Eight apical sensilla known to be olfactory are observed on the distal end of the maxillary palpus. The gustatory structures i.e., two sensory structures (ALP1 and ALP2), a fine sensory projection (STC), two sensory setae (SL1 and SL2) are observed on the maxillary palpi. A single pair of labial palpi, considered to be mechanoreceptors, is also observed. Further, the functional morphology of the sensory receptors on the head capsule of other lepidopterous larvae have also been discussed.
Influences of Wolbachia (Rickettsiales Rickettsiaceae) on the cellular response to cold stress in Drosophila melanogaster (Diptera Drosophilidae)
Get PDFWolbachia pipiensis (Hertig et Wolbach, 1924) is known to manipulate the expression of genes implicated in the metabolism, immunity and reproduction in Drosophila melanogaster (Meigen, 1830). Under stress, cells activate the cellular stress response (CSR). The CSR is a conserved network of pathways regulating identification, check and response to stress, preserving the cellular homeostasis. The CSR involves the unfolded protein response, autophagy, the heat shock response and other subcellular pathways. How Wolbachia affects the CSR has not yet been investigated. Here, we report the influence of Wolbachia infection and cold stress on the expression of the Heat-shock-protein-70Aa (Hsp70Aa), Autophagy-related gene-1 (Atg1) and X box binding protein-1 (Xbp1) genes and the influence of cold stress on the Wolbachia surface protein gene (wsp). The Hsp70Aa, Atg1, and Xbp1 genes were affected by Wolbachia infection since they were found to be up-regulated in the Wolbachia-free flies. After cold stress, the Wolbachia-infected flies showed high expression of the Atg1 and Hsp70Aa genes in comparison to the Wolbachia-free flies. Moreover, cold stress negatively influenced the expression of the wsp gene
Screening of local Italian maize varieties for resistance to Fusarium verticillioides
Get PDFIn order to find maize genetic sources of resistance to Fusarium attack and to fumonisin accumulation, 27 Italian local varieties collected at the CREA (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Unità di ricerca per la maiscoltura) maize gene bank, were evaluated in artificial inoculation field experiments during 2011 and 2012 seasons.
Primary ears were inoculated with a mixture of two Fusarium verticillioides toxigenic strains through kernel inocula- tion; non-inoculated and sterile water-inoculated ears were included as controls. Disease severity was estimated by counting the kernels with visible symptoms of infection at the inoculation point. The percentage of internally contaminated kernels was detected and fumonisin accumulation was recorded. Results showed that, under artifi- cial inoculation, genotypes responded differentially to the Fusarium attack. Five out of 27 genotypes (VA56, VA70, VA74, VA114, and VA121) showed a low fumonisin content both in 2011 and 2012, seasons characterized by very different climatic conditions
Heterosis and combining ability of highland quality protein maize inbred lines
Get PDFQuality protein maize (QPM) cultivars contain higher levels of lysine and tryptophan as compared to non-QPM counterparts, and can minimize the risk of protein malnutrition among communities increasingly dependent on maize as their food staple. This study was undertaken to assess the performances of QPM hybrids, and estimate heterosis and combining ability effects of highland QPM inbred lines for grain yield, agronomic and protein quality traits. Hybrids of 20 inbred lines and two testers, and the parental lines were evaluated across three locations in Ethiopia. Significant variations were observed among the parents and the hybrids for almost all measured traits that allows the selection of preferred inbred lines and hybrids. Several hybrids showed desirable heterosis for most studied traits. Mean squares attributable to general (GCA) and specific (SCA) combining ability effects were significant for most traits. However, the contributions of GCA sum of squares to the variation among the hybrids were larger than SCA sum of squares, suggesting that the traits were conditioned mainly by additive gene effects. Inbred lines L12, L17, L19, and L20 had desirable GCA effects for grain yield, whereas L12 and L13 were the best general combiners for protein quality traits. Hybrids L17 x 142-1eQ and L20 x 142-1-eQ showed most desirable perse performances and SCA effects for grain yield. Based on grain yield SCA effects, most inbred lines used in the study were grouped into distinctive heterotic patterns. This study indicated the possibility of developing high- land QPM germplasm with acceptable grain yield, agronomic and protein quality traits
Screening of sorghum (Sorghum bicolor L) genotypes under various levels of drought stress
Get PDFSorghum is an important fodder crop and plays an important role in the Pakistan dairy industry. High yielding and superior quality sorghum varieties should be produced to meet the domestic needs. In arid and semiarid regions, drought is a major and serious constraint to sorghum production and adversely influences sorghum growth and germination. There are many approaches to combat the drought stress. Among these approaches breeding of crops contributes towards increase in yield under stress condition like drought stress by making the plant tolerant against stress. Ten genotypes of sorghum were evaluated at seedling stage to determine the genotypic variation among them on the basis of tolerance against drought stress and impact of drought on fodder quality. Three levels of water (100%, 75%, and 50% field capacity) were applied to the genotypes. The experiment was carried out in wire house following a triplicate completely randomized design with factorial arrangements. The data were re- corded after 20 days of sowing on following traits such as root and shoot length, root shoot fresh and dry weight, leaf area, crude protein, relative water content, total ash contents and chlorophyll contents. Significant differences were found among the genotypes for all traits. The genotypes NARC-11 followed by Sorgh-11 gave better re- sponse in all levels of drought stress while F-114 gave poor response in all levels of drought stress
Salicylic acid alleviates methyl viologen induced oxidative stress through transcriptional modulation of antioxidant genes in Zea mays L
Get PDFSalicylic acid (SA) is an important growth regulator that participates in both biotic as well as abiotic stress re- sponse in plants. Both-biotic and abiotic stresses are characterized by elevated cellular reactive oxygen species (ROS). We examined the biochemical and molecular effects of SA on the ROS scavenging system in maize. Pre- treatment of maize plants with SA prior to stress, reduced electrolyte leakage, enhanced protein accumulation, improved root biomass and grain yield. SA application also led to a general enhancement in the biochemical activities of three major ROS scavenging antioxidant enzymes, viz. superoxide dismutase (SOD), catalase (CAT) and peroxidases (POX). However, corresponding transcripts of various antioxidant isozymes depicted a dynamic response for different SA doses. Under stress, pre-treatment with 0.5 mM SA led to enhanced expression of all the Sod genes analyzed while higher SA concentration repressed many Sod genes. Cat 1 showed clear dose- dependent repression in response to graded concentrations of SA, while Cat 3 showed inverse dose-dependent activation in response to graded concentrations of SA. Apx 1 was found to be up-regulated at 0.5 mM SA, while higher doses of SA, i.e. 1.0 and 1.5 mM led to its repression. All the three concentrations of SA repressed Apx 2 gene. Taken together, our results indicate that SA has the potential to alleviate oxidative stress in maize through biochemical and transcriptional modulation of ROS scavenging pathway. Also, the concentration of SA has a great bearing in its alleviating role, with lower concentrations (viz 0.5 mM) being more desirable
Genetic variability, repeatability, traits relationships and path coefficient analysis in low nitrogen donor white inbred lines of maize (Zea mays L)
Get PDFGenetic variability of agronomic traits of crops broadens the gene pool of crops. Repeatability and genetic ad- vance determine the effectiveness of selection in breeding programme. Hence, phenotypic and genotypic vari- ances, genotypic coefficient of variation, repeatability and expected genetic advance were estimated for three flowering and six morphological traits of white kernel low nitrogen donor maize inbred lines. Significant difference existed in the nine traits. Genotypic and phenotypic variances were equal for floral traits. Thus, gene actions for the traits was additive. Repeatability was high for the nine traits. In addition to high repeatability, anthesis-silking interval showed high genetic advance with high coefficient of variation suggesting its efficiency for selection. Phenotypic and genotypic correlations of grain yield with each of days to anthesis, plant height, ear height, leaf area and number of ear per plant were positive and significant. Genetic effect for grain yield correlated with that of days to silking, but this was not for phenotypic effect. Any of these traits can be selected for grain yield and the lines studied were considered suitable as gene pool in maize breeding for nitrogen stress tolerance. Path analysis showed that days to silking, leaf area and ear per plant had high positive effect with grain yield of the crop
Effect of moisture stress on combining ability and gene action for polygenic traits in maize
Get PDFPresent study was carried out to assess the general combining ability effects of parents and specific combining ability effects of hybrids for yield and yield related traits purely under rainfed situations. Incidently, it mimicked mid season drought conditions i.e. moisture stress at flowering stage for a period of 22 days. Combining ability analy- sis using Line × Tester design was conducted in maize (Zea mays L) inbred lines by growing 135 F ’s generated by crossing fifteen lines with nine testers at ARS, Karimnagar, PJTSAU during rainy season, 2011. Female lines were derived from the recurrent selection cycle carried out in the drought tolerant population «Tuxpeno Sequia», procured from CIMMYT in 1996. Males were developed using pedigree breeding. Analysis of variance showed highly significant genotypic differences for all the traits studied indicating wide range of variability among the geno- types. The ratio of gca /sca was less than unity indicating the preponderance of non-additive gene action in the expression of all the characters studied except flowering traits. Moderate narrow sense heritability was observed for majority of the characters. Three lines KMLD-3, KMLD-11, and KMLD-19 and one tester, KML-9 were good general combiners for grain yield and one or more yield contributing characters. The crosses KMLD-3 × KML-99, KMLD-5 × BML-7, KMLD-5 × KML-801, KMLD-6 × KML-36, and KMLD-11 × KML-29 showed significant positive sca, standard heterosis and high mean values for grain yield plant-1 and two or more yield components. These hybrids were found to be early in flowering with significant negative heterosis providing some clue about their use- fulness under drought conditions. Therefore further testing of these new inbred lines for use in a crossing program is recommended to combine major yield components with high yield to derive climate resilient hybrids
Selection response for oil content and agronomic performance in four subtropical maize populations
Get PDFHigh oil content (HOC) maize (Zea mays L) genotypes may have an economic impact on animal husbandry and on food and feed industries in several countries due to their related high digestible energy value. Almost all knowledge about cultivating oil accumulation in maize kernels, using recurrent selection, have been generated in temperate regions, but very little is known about the genotypes commonly grown in subtropical regions. With the intention of developing the HOC in a subtropical maize germplasm in Celaya Mexico in 2004, a half-sib recurrent selec- tion scheme was initiated using near infrared spectrophotometry in four Bajio and Northwest varieties of white and yellow kernel populations (BWP, NWP, BYP, and NYP). With the aim to study the selection response for oil content, grain yield and other traits, field experiments conducted during 2011 in Morelia, and during 2011 and
2012 in Celaya. Results by location and combined across locations showed no significant changes within popula- tions in terms of grain yield and other agronomic characteristics, which is in contrast to the literature (grain yield has been show to decline as oil content increased). This response is due to the employed field selection criteria, which emphasized selecting healthy, top-yielding and agronomically superior individuals from each population. Regarding the oil content, a gradual increase over several cycles was obtained in the selected populations, us- ing a selection gain per cycle of 0.31%, 0.40%, 0.27%, and 0.30% for BYP, NYP, BWP, and NWP, respectively. These improved populations contained final oil contents of 7.5%, 8.1%, 7.6%, and 6.7%, for BYP, NYP, BW, P, and NWP, respectively
Microgeographic diversity of Uropodina (Acari Mesostigmata) communities in dead wood and tree hollows
Get PDFThe current study is aimed at establishing species composition of Uropodina mite fauna in dead wood habitats in a selected forest complex in western Poland. In this case the study focuses on three natural reserves of Wielkopolska. In 278 samples of dead wood and 71 from tree hollows collected between 2002-2004, 27 species of Uropodina were found. The material collected from the tree hollows contained only 12 species. The two species that were most numerous in the analysed material were Oodinychus ovalis and Olodiscus minima. The lower number of species inhabiting the tree hollows stems from the fact that such microhabitats are isolated inaccessible places. The main factor that is responsible for the difference in the abundance of uropodine mites in both microhabitats are seasonal changes in temperature. Moreover, the results of the analyses show that species composition of Uropodina communities in dead wood and tree hollows can be different even within one forest complex, which suggests that the process of diversification in Uropodina communities inhabiting dead wood merocoenoses probably takes place at the microgeographic level