Authors:Anita Lukács, Zsuzsanna Lengyel, L. Institóris and Andrea Szabó
Young adult male Wistar rats were treated, by gavage, with 80 or 320 mg/kg Pb
(lead acetate), 0.4 or 1.6 mg/kg Hg
(mercuric chloride) or both by combining the lower doses. For combination with alcohol, ethanol was added to the rats’ drinking water in 5 v/v %. After 12 weeks of treatment, electrophysiological recording was made from the somatosensory cortex in urethane anaesthesia. Evoked potentials obtained by stimulation of the whiskers were recorded. Both metals, and alcohol alone, increased significantly the latency of the evoked response. Alcohol seemed to abolish the effect of Pb, but not of Hg. Fatigue, calculated form the response amplitude, was increased by Pb and Hg treatment and this effect of Hg was reduced by ethanol. Evoked activity and its dynamic characteristics were sensitive to the complex neurotoxic effect induced in the rats and can provide a basis for developing functional markers.
Authors:A. Etminan, A. Pour-Aboughadareh, R. Mohammadi, A. Noori and A. Ahmadi-Rad
Progress in plant molecular tools has been resulted in the development of gene-targeted and functional marker systems. CAAT box region is a different pattern of nucleotides with a consensus sequence, GGCCAATCT, which situated upstream of the start codon of eukaryote genes and plays an important role during transcription. In the present study, several CAAT box-derived polymorphism (CBDP) primers were used for fingerprinting in mini-core collection of durum wheat (including internationally developed breeding lines and Iranian landraces). Twelve selected primers amplified 98 loci, of which all were polymorphic. The average values of the polymorphism information content (PIC) and resolving power (Rp) were 0.31 and 9.16, respectively, indicating a high level of variability among studied genotypes. Analysis of molecular variance (AMOVA) indicated that 92% of the total variation resided among populations. The values of the percentage polymorphic bands (PPL), the observed (Na) and effective (Ne) number of alleles, Nei’s gene diversity (He) and Shannon’s information index (I) for Iranian landraces were higher than the breeding lines. The Fandendrogram obtained by cluster analysis grouped all individuals into three main clusters. Our results showed a remarkable level of genetic diversity among studied durum wheat, especially among Iranian landraces, which can be interest for future breeding programs. More importantly, the present study also revealed that CBDP technique was efficient and powerful tool to assess genetic diversity in wheat germplasm. Hence, this technique could be employed individually or in combination with other molecular markers to evaluate genetic diversity and relations among different species.
Authors:V. Pachauri, V. Mishra, P. Mishra, A.K. Singh, S. Singh, R. Singh and N.K. Singh
The present report is in continuation to our earlier reports on the identification and fine mapping of three aroma QTLs in basmati rice using a bi-parental mapping population derived from a cross between Pusa 1121, a basmati rice variety, and Pusa 1342, a non-aromatic rice variety. We used a combination of genetic mapping and transcriptome profiling to narrow down the number of differentially expressed genes in rice to identify potential candidate genes for rice grain aroma. Highly aromatic and non-aromatic recombinant inbred lines (RILs) were identified through sensory analysis of mature milled grains. RILs with similar phenotypes were bulked together using bulk segregant analysis approach which drastically reduced the number of differentially expressed genes from 4016 to 1344. The transcriptome profiles generated were analyzed through Affymetrix rice genome array containing probe sets designed from all the predicted rice gene sequences. Microarray-based transcriptome profiling revealed one down-regulated gene co-located in QTL region aro3.1 on chromosome 3, eight genes co-located in the aro4.1 region on chromosome 4 and the badh2 gene on chromosome 8 to be differentially expressed in the aromatic parent and aromatic bulk. These genes are the most suitable candidates for future validation and development of new molecular functional markers to facilitate marker assisted breeding.
Authors:Hongxiang M, Jinbao Yao, Miaoping Zhou, Xu Zhang, Lijuan Ren, Giuhong Yu and Weizhong Lu
Wheat Fusarium head blight (FHB) may cause serious losses in grain yield and quality in China. More than 7 million hectares which approximately accounts for 25% of the total areas in China is infected by the disease. The cultivation of wheat varieties with resistance to Fusarium head blight is recognized as one of the most important components to diminish losses due to this disease. Chinese wheat breeders have commenced the research on FHB since 1950s. Wheat cultivars with improved FHB resistance were developed through conventional breeding. Some famous resistant varieties such as Sumai 3, Yangmai 158 and Ning 7840 were released from Jiangsu Academy of Agricultural Sciences, these varieties were widely applied in wheat production and breeding programs. Significant achievements concerning molecular mapping and marker assisted selection have been made in the past decade. The major QTL on chromosome 3BS was identified and located in the same region on chromosome 3BS in Sumai 3, Ning 894037, Wangshuibai, and Chinese Spring. Using SSR marker in this QTL region for assisted selection, some lines with the same resistance to FHB were obtained. New STS markers and SSCP markers were developed and will be tested for the efficiency of MAS. However, further achievements are still hindered by a number of constraints. More FHB resistance genetic resources from landrace in middle to lower reaches of Yangtze River are necessary to be used for improving FHB resistant. The genetic mechanism of the varieties contributing the resistance to improved cultivars is needed to be understood. Development of functional markers for FHB is discussed.
Authors:M. Ciuca, D. Cristina, A.G. Turcu, E.L. Contescu, V. Ionescu and N.N. Saulescu
Wheat continues to be one of the most cultivated cereals in the world, and also in Romania. Leaf rust caused by Puccinia triticina reduces the wheat yield and grains quality worldwide. In the context of climate change, leaf rust has become a more important problem for both wheat growers and breeders in our country. Use of genetic resources, carrying rust resistance genes, play an important role in breeding programs leading to resistant varieties, which can have positive impact on environment and economy. Therefore, the identification of resistance genes in modern wheat cultivars and breeding lines, and then selection of the best resistance genes combination(s) are the first steps for a successful breeding program. At present, one of the best known and studied adult plant leaf rust resistance gene is Lr34 that contributes significantly to durable leaf rust resistance. The functional markers that enable early detection of this gene are a major advantage in the wheat breeding.
The aim of this study was to evaluate the presence of the slow rusting resistance gene Lr34 in Romanian wheat germplasm, using cssfr4 and cssfr5 molecular markers. Screening of 47 winter bread wheat cultivars and 47 breeding lines with these markers showed the presence of the Lr34 resistant haplotype in 62% (homozygous genotypes) of the total genotypes. A high frequency (79%) of Lr34 resistance allele was found among 47 breeding lines, suggesting that maintenance of a high frequency of this allele represents a real advantage for the development of adult plant resistance in Romanian breeding programs.
Authors:I.N. Leonova, A.I. Stasyuk, E.S. Skolotneva and E.A. Salina
Cultivation of winter wheat varieties in the West Siberian region of Russia has competitive advantages compared to spring varieties: utilization of spring-summer moisture, early maturation and harvest and a high yield potential. The poor resistance of winter varieties to foliar diseases results in significant yield losses and facilitates the spread of pathogens to the spring wheat cultivars. The present study was conducted to evaluate the effectiveness of molecular markers specific for VRN-1 and Lr loci in selecting winter wheat genotypes resistant to leaf rust. The winter wheat cultivars Biyskaya ozymaya and Filatovka were crossed with spring wheat introgression lines 21-4 and 5366-180 and the spring wheat cultivar Tulaikovskaya 10 carrying LrTt2, LrAsp5 and Lr6Ai#2 loci from Triticum timopheevii, Aegilops speltoides and Thynopyrum intermedium, respectively. To identify winter wheat plants homozygous for target loci, F2 populations were screened with functional markers to VRN-1 genes and with markers specific for alien genetic material. Based on the genotyping analysis of 371 F2 plants a total of 44 homozygous genotypes with winter habit was identified. There were eight genotypes containing Lr loci among them. Evaluation of F2-derived F3-4 families for both seedling and adult resistance showed that only one F3-4 family had moderate susceptible reaction type to the field population of leaf rust. Others ranged from nearly immune to resistant with severity of 5%. The data also indicated the utility of the VRN-1 allele-specific markers for detection of genotypes with winter habit without vernalization at early stages of plant breeding.
Authors:N. Zhang, R.Q. Pan, J.J. Liu, X.L. Zhang, Q.N. Su, F. Cui, C.H. Zhao, L.Q. Song, J. Ji and J.M. Li
Plants with deficiency in Gibberellins (GAs) biosynthesis pathway are sensitive to exogenous GA3, while those with deficiency in GAs signaling pathway are insensitive to exogenous GA3. Thus, exogenous GA3 test is often used to verify whether the reduced height (Rht) gene is involved in GAs biosynthesis or signaling pathway. In the present study, we identified the genetic factors responsive to exogenous GA3 at the seedling stage of common wheat and analyzed the response of the plant height related quantitative trait loci (QTL) to GA3 to understand the GAs pathways the Rht participated in. Recombinant inbred lines derived from a cross between KN9204 and J411 with different response to exogenous GA3 were used to screen QTL for the sensitivity of coleoptile length (SCL) and the sensitivity of seedling plant height (SSPH) to exogenous GA3. Two additive QTL and two pairs of epistatic QTL for SCL were identified, meanwhile, two additive QTL and three pairs of epistatic QTL for SSPH were detected. For the adult plant height (PH) investigated in two environments, six additive QTL were identified. Three QTL qScl-4B, qSsph-4B and qPh-4B were mapped in one cluster near the functional marker Rht-B1b. When PH were conditional on SSPH, the absolute additive effect value of qPh-4B and qPh-6B were reduced, suggesting that the Rhts in both two QTL were insensitive to exogenous GA3, while the additive effect values of qPh-2B, qPh-3A, qPh-3D and qPh-5A were not significantly changed, indicating that the Rhts in these QTL were sensitive to exogenous GA3, or they were not expressed at the seedling stage.
Garnier, E., J. Cortez, G. Billès, M.-L. Navas, C. Roumet, M. Debussche, G. Laurent, A. Blanchard, D. Aubry, A. Bellmann, C. Neill and J.-P. Toussaint. 2004. Plant functionalmarkers capture ecosystem properties during secondary succession.