Non-responsive Genotypes Research Articles

Variation in microbial feature perception in the Rutaceae family with immune receptor conservation in citrus.

Although much is known about the responses of model plants to microbial features, we still lack an understanding of the extent of variation in immune perception across members of a plant family. In this work, we analyzed immune responses in Citrus and wild relatives, surveying 86 Rutaceae genotypes with differing leaf morphologies and disease resistances. We found that responses to microbial features vary both within and between members. Species in 2 subtribes, the Balsamocitrinae and Clauseninae, can recognize flagellin (flg22), cold shock protein (csp22), and chitin, including 1 feature from Candidatus Liberibacter species (csp22CLas), the bacterium associated with Huanglongbing. We investigated differences at the receptor level for the flagellin receptor FLAGELLIN SENSING 2 (FLS2) and the chitin receptor LYSIN MOTIF RECEPTOR KINASE 5 (LYK5) in citrus genotypes. We characterized 2 genetically linked FLS2 homologs from "Frost Lisbon" lemon (Citrus ×limon, responsive) and "Washington navel" orange (Citrus ×aurantium, nonresponsive). Surprisingly, FLS2 homologs from responsive and nonresponsive genotypes were expressed in Citrus and functional when transferred to a heterologous system. "Washington navel" orange weakly responded to chitin, whereas "Tango" mandarin (C. ×aurantium) exhibited a robust response. LYK5 alleles were identical or nearly identical between the 2 genotypes and complemented the Arabidopsis (Arabidopsis thaliana) lyk4/lyk5-2 mutant with respect to chitin perception. Collectively, our data indicate that differences in chitin and flg22 perception in these citrus genotypes are not the results of sequence polymorphisms at the receptor level. These findings shed light on the diversity of perception of microbial features and highlight genotypes capable of recognizing polymorphic pathogen features.

Screening of diverse cassava genotypes based on nitrogen uptake efficiency and yield

As one of the top three tuber crops of the world, cassava is a staple food and feed crop for tropical and subtropical regions. Because of its high drought resistance and tolerance to nutrient deficiency, cassava is usually cultivated on hilly areas that are nutrient-poor. Nitrogen (N) is one of the significant factors affecting cassava yield. A double factorial (N level×genotypes) split-plot field experiment was conducted to analyze differences in yield and N accumulation of 25 cassava genotypes under low-N conditions to screen for cassava genotypes with high-N efficiency. The two-year field experiment showed that cassava yield and N accumulation are determined by specific genotypes, soil N levels, and year. Among these factors, soil N levels are the main factors that are responsible for differences in cassava yield. When yield and relative N accumulation under low-N conditions were used as screening markers, we identified an efficient and responsive genotype (SC10), and two inefficient and non-responsive genotypes (SC205 and GR5). The efficient and responsive genotype and the inefficient and non-responsive genotype can be used as study materials to further reveal the mechanisms for high-N efficiency in cassava.

Categorization of Diverse Wheat Genotypes for Zinc Efficiency Based on Higher Yield and Uptake Efficiency

Low zinc (Zn) availability in various agricultural soils including Vertisols adversely affects wheat production. The variations among the wheat genotypes to produce high grain yield and Zn uptake under low Zn supply were investigated to find out the Zn-efficient genotypes. Twenty-five different wheat genotypes were evaluated in the field with two levels of Zn, viz., low (no Zn fertilizer) and high (20 kg of Zn ha−1 applied as Zn sulfate heptahydrate (ZnSO4.7H2O) (21% Zn)) along with three foliar applications of Zn at ear initiation, flowering, and milking stage of wheat growth. Thousand grain weight, grain yield, grain Zn concentration, and Zn uptake of wheat genotypes differed significantly and increased due to Zn application. Among the genotypes, grain yield efficiency index (i.e., relative grain yield) varied from 85.0 to 98.6 and Zn uptake efficiency (i.e., relative grain Zn uptake) varied from 60.9 to 88.5. Considering grain yield efficiency index and Zn uptake efficiency index, the genotypes were categorized as efficient and responsive (JW-3211, GW-322, PBW-502, HD-2864, UP-2554, HI-8627, GW-190, SUJATHA-HI-627), efficient and non-responsive (HD-2932, LOK-1, PBW-175), inefficient and responsive (HD-4672, GW-366, UP-2628), and inefficient and non-responsive (HW-2004, WH-147, HI-1418, DL-803-3, PBW-343, HD-2733, UP-2565, JW-17, C-306, AKW-4627, HI-1500). The efficient and responsive genotypes are the most useful ones as they provide higher yield under low Zn supply and also respond to Zn fertilizer application. The inefficient and responsive genotypes may be utilized by the plant breeders to identify the responsive traits for their incorporation in modifying the efficient and non-responsive genotypes.

Stress and cell cycle regulation during somatic embryogenesis plays a key role in oil palm callus development

Oil palm is an oleaginous plant of relevant economic importance since its fruits are rich in vegetable oil. These plants have a single apical meristem and the main method for vegetative propagation is somatic embryogenesis. The aim of this study was to identify differentially abundant proteins from oil palm genotypes contrasting in the capacity of embryogenic competence acquisition, using shotgun proteomics. Oil palm leaves were subjected to callus induction and the material was collected in biological triplicates at 14 and 90 days of callus induction. LC-MS/MS analysis was performed and revealed a total of 4695 proteins. Responsive and non-responsive genotypes were compared at 14 and 90 days of callus induction and 221 differentially abundant proteins were obtained. The data analysis revealed several proteins mainly related to energy metabolism, stress response and regulation of cell cycle, further analyzed by qRT-PCR, which seem important for embryogenic development. We suggest some of these proteins as key factors for the success of callus formation in oil palm including antioxidant and cell division proteins as well as proteins involved in the ubiquitination pathway. These proteins may also be potential biomarkers for the acquisition of embryogenic competence. SignificanceAntioxidant and cell division proteins as well as proteins involved in the ubiquitination pathway are key factors for the success of callus formation in oil palm. The proteins identified in this study may be potential biomarkers for embryogenic competence acquisition.

Nitrogen supply influences photosynthesis establishment along the sugarcane leaf

Nitrogen (N) is a major component of the photosynthetic apparatus and is widely used as a fertilizer in crops. However, to the best of our knowledge, the dynamic of photosynthesis establishment due to differential N supply in the bioenergy crop sugarcane has not been reported to date. To address this question, we evaluated physiological and metabolic alterations along the sugarcane leaf in two contrasting genotypes, responsive (R) and nonresponsive (NR), grown under high- and low-N conditions. We found that the N supply and the responsiveness of the genotype determined the degree of senescence, the carboxylation process mediated by phosphoenolpyruvate carboxylase (PEPcase) and differential accumulation of soluble sugars. The metabolite profiles indicated that the NR genotype had a higher respiration rate in the youngest tissues after exposure to high N. We observed elevated levels of metabolites related to photosynthesis in almost all leaf segments from the R genotype under high-N conditions, suggesting that N supply and the ability to respond to N influenced photosynthesis. Therefore, we observed that N influence on photosynthesis and other pathways is dependent on the genotype and the leaf region.

Gene expression analysis of primordial shoot explants collected from mature white spruce (Picea glauca) trees that differ in their responsiveness to somatic embryogenesis induction.

Within a plantation of clonal somatic embryo-derived white spruce trees that belonged to four genotypes, one genotype (G6) has consistently responded for the last 16 years, to the induction of somatic embryogenesis within primordial shoot explants. Analysis of fourteen individuals within this genotype subsequently revealed a group of clonal trees that were nonresponsive. This in turn provided a unique opportunity to conduct differential gene expression analysis in the absence of genotype-specific factors. Absolute qPCR was first used to expand the analysis of several genes previously identified via microarray analysis to be differentially expressed during SE induction, along with the inclusion of two nonresponsive genotypes. While this demonstrated a high level of repeatability within, and between, responsive and nonresponsive genotypes, it did not support our previous contention that an adaptive stress response plays a role in SE induction responsiveness, at least with respect to the candidate genes we analyzed. RNAseq analysis was then used to compare responsive and nonresponsive G6 primordial shoots during the somatic embryogenesis induction treatment. Although not analyzed in this study, this included samples of callus and embryonal masses previously generated from G6 explants. In addition to revealing a large number of differentially expressed genes, de novo assembly of unmapped reads was used to generate over 25,000 contigs that potentially represent previously unidentified transcripts. This included a MADS-domain gene that was found to be the most highly differentially expressed gene within responsive shoot explants during the first seven days of the induction treatment.

Response to Fertilization Associated to Leaf Mineral Content in Strawberry

Leaf mineral content along the crop cycle may explain differences in response to fertilization among strawberry genotypes. A two year field experiment was conducted using responsive (‘Camarosa’, ‘Ventana’) and nonresponsive (‘Camino Real’, ‘Candonga’) to fertilization genotypes under proportional increases in nutrients supply: from a control dose “C” [120 kg nitrogen (N) ha−1, 70 kg phosphorus pentoxide (P2O5) ha−1, 220 kg potassium oxide (K2O) ha−1, 40 kg calcium oxide (CaO) ha−1 and 20 kg magnesium oxide (MgO) ha−1] to “1.33C” and “1.66C” in 2007 and to “1.5C” and “2C” in 2008. Response to fertilization was high (45–120%) at begining of harvesting and low (10-28%) at middle and end of harvesting. Correlation between leaf area and total yields was high (r ≈ 0.73) at begining of harvesting, except on ‘Camino Real’ (late and compact genotype). At begining of flowering and harvesting, responsive genotypes showed higher potassium (K) and lower calcium (Ca) leaf contents than nonresponsive genotypes, accentuated with the fertilization increase.

Mutations in the STAT1-interacting domain of the hepatitis C virus core protein modulate the response to antiviral therapy

RNA viruses, such as hepatitis C virus (HCV), have markedly error-prone replication, resulting in high rates of mutagenesis. In addition, the standard treatment includes ribavirin, a base analog that is likely to cause mutations in different regions of the HCV genome, resulting in deleterious effects on HCV itself. The N-terminal region of the core protein is reported to block interferon (IFN) signaling by interaction with the STAT1‑SH2 domain, resulting in HCV resistance to IFN therapy. In this study, mutations in the HCV core protein from IFN/ribavirin‑treated patients were analyzed, with particular focus on the N‑terminal domain of the HCV core which is reported to interact with STAT1. HCV PCR positive patients enrolled in this study were either undergoing pegylated IFN/ribavirin bitherapy and had completed 12 weeks of initial treatment or were treatment‑naïve patients. The HCV core protein was cloned and sequenced from these patients and mutations observed in the STAT1‑interacting domain of the core protein from treated patients were characterized using in silico interaction to depict the role of these mutations in disease outcomes. Our results suggest that the amino acids at positions 2, 3, 8, 16 and 23 of the HCV core protein are critical for core-STAT1 interaction and ribavirin-induced mutations at these positions interfere with the interaction, resulting in a better response of the treated patients. In conclusion, this study anticipates that HCV core residues 2, 3, 8, 16 and 23 directly interact with STAT1. We propose that IFN/ribavirin bitherapy‑induced mutations in the STAT1‑interacting domain of the HCV core protein may be responsible for the improved therapeutic response and viral clearance, thus amino acids 1-23 of the N-terminus of the core protein are an ideal antiviral target. However, this treatment may give rise to resistant variants that are able to escape the current therapy. We propose similar studies in responsive and non-responsive genotypes in order to gain a broader picture of this proposed mechanism of viral clearance.

Potential link between biotic defense activation and recalcitrance to induction of somatic embryogenesis in shoot primordia from adult trees of white spruce (Picea glauca).

BackgroundAmong the many commercial opportunities afforded by somatic embryogenesis (SE), it is the ability to clonally propagate individual plants with rare or elite traits that has some of the most significant implications. This is particularly true for many long-lived species, such as conifers, but whose long generation times pose substantive challenges, including increased recalcitrance for SE as plants age. Identification of a clonal line of somatic embryo-derived trees whose shoot primordia have remained responsive to SE induction for over a decade, provided a unique opportunity to examine the molecular aspects underpinning SE within shoot tissues of adult white spruce trees.ResultsMicroarray analysis was used to conduct transcriptome-wide expression profiling of shoot explants taken from this responsive genotype following one week of SE induction, which when compared with that of a nonresponsive genotype, led to the identification of four of the most differentially expressed genes within each genotype. Using absolute qPCR to expand the analysis to three weeks of induction revealed that differential expression of all eight candidate genes was maintained to the end of the induction treatment, albeit to differing degrees. Most striking was that both the magnitude and duration of candidate gene expression within the nonresponsive genotype was indicative of an intense physiological response. Examining their putative identities further revealed that all four encoded for proteins with similarity to angiosperm proteins known to play prominent roles in biotic defense, and that their high-level induction over an extended period is consistent with activation of a biotic defense response. In contrast, the more temperate response within the responsive genotype, including induction of a conifer-specific dehydrin, is more consistent with elicitation of an adaptive stress response.ConclusionsWhile additional evidence is required to definitively establish an association between SE responsiveness and a specific physiological response, these results suggest that biotic defense activation may be antagonistic, likely related to the massive transcriptional and metabolic reprogramming that it elicits. A major issue for future work will be to determine how and if suppressing biotic defense activation could be used to promote a physiological state more conducive to SE induction.

Analysis of Gene Variants Previously Associated With Iloperidone Response in Patients With Schizophrenia Who Are Treated With Risperidone

We examined 6 single nucleotide polymorphisms (SNPs) previously reported to be associated with response to iloperidone therapy for association with response to risperidone therapy. Patients with schizophrenia (DSM-IV) were assessed during 2006 and 2007 for response/nonresponse (defined as ≥ 20%/<20% improvement in Positive and Negative Syndrome Scale [PANSS] total score) after 2 weeks of risperidone treatment (2 to 6 mg/d). Responders continued risperidone treatment; nonresponders were randomly assigned to either risperidone or olanzapine treatment (10 to 20 mg/d) for an additional 10 weeks. Associations between change in PANSS total (primary outcome measure), positive, and negative scores and the 6 SNPs were examined in risperidone-treated patients (N = 145). Genotype frequencies and improvement in PANSS total scores were analyzed for those SNPs significantly associated with change in PANSS total score. The SNPs XKR4 rs9643483 and GRIA4 rs2513265 were significantly associated with change in PANSS total response (adjusted P < .05 for both), with the same direction of effect as reported for iloperidone. For patients with nonresponsive genotypes for these SNPs, mean improvement in PANSS total score for African Americans was two-thirds that seen for whites (XKR4: -13.9 versus -21.4; GRIA4: -12.5 versus -20.9). In this retrospective pharmacogenomic analysis, we found that 2 SNPs previously linked to iloperidone response were also associated with response to risperidone. clinicaltrials.gov Identifier: NCT00337662.

Study on The Efficacy of Nitrogen Utilization by Rice Genotypes Part 1: Clustering and Selection for Rice Genotypes

This experiment was carried out in a greenhouse as, the first part of four consecutive experiments. Sixty rice genotypes comprising 30 national and 30 local genotypes were evaluated for their responses and efficacy to nitrogen (N, urea) fertilizer application. Two levels of N fertilizer, i.e., 0 (N1) and 120 (N2) kg of N per hectare were applied. Randomized Block Design (RBD) with three replications was used as the experimental design. The observed parameters were grain yield per pot and grain yield index (GI). Based on average of grain yield of N1, average of grain yield of N2, and grain yield index (GI), the 60 evaluated genotypes were classified into four clusters. These clusters consisted of 26 efficient and responsive (ER) genotypes, 7 efficient and non-responsive (ENR) genotypes, 6 non-efficient and responsive (NER) genotypes, and non-efficient and non-responsive (NENR) genotypes. Replacement of cultivars in rice cultivation, from non efficient (NE)-genotype to efficient (E)-genotype has a potential of yield increase of 90.83%, replacement of non-responsive (NR) with responsive (R) genotype has a potential yield increase of 59.57%, replacement of local genotypes with national genotypes has a potential to increase yield 8.66% only. Of the 26 ERs, genotypes with the highest efficiency were Singkil, IR-66, Indragiri, Sintanur, and Widas. Genotypes with the highest response were Ciliwung, IR-66, Ciherang, Sintanur, and Cisadane. These genotypes can be used to increase rice production, to reduce production costs and to reduce environmental pollution. The ER, ENR and NER genotypes can be used as parents in breeding for high yielding and N efficient rice genotypes.

Crop improvement in the era of climate change: an integrated, multi-disciplinary approach for common bean (Phaseolus vulgaris).

Climate change and global population increase are two converging forces that will jointly challenge researchers to design programs that ensure crop production systems meet the world's food demand. Climate change will potentially reduce productivity while a global population increase will require more food. If productivity is not improved for future climatic conditions, food insecurity may foster major economic and political uncertainty. Given the importance of grain legumes in general - common bean (Phaseolus vulgaris L.) in particular - a workshop entitled 'Improving Tolerance of Common Bean to Abiotic Stresses' was held with the goal of developing an interdisciplinary research agenda designed to take advantage of modern genotyping and breeding approaches that are coupled with large scale phenotyping efforts to improve common bean. Features of the program included a multinational phenotyping effort to evaluate the major common bean core germplasm collections and appropriate genetic populations. The phenotyping effort will emphasise the response of root and shoot traits to individual and combined stress conditions. These populations would also be genotyped using newly emerging high density single nucleotide polymorphism (SNP) marker arrays or next generation sequencing technology. Association analysis of the core collections aims to identify key loci associated with the response to the stress conditions. Companion bi-parental quantitative trait loci (QTL) experiments will act as confirmation experiments for the association analysis. The upcoming release of the genome sequence of common bean will be leveraged by utilising population genomic approaches to discover genomic regions that differentiate stress-responsive and non-responsive genotypes. The genome sequence will also enable global gene expression studies that will highlight specific molecular-based stress responses. This collective knowledge will inform the selection of parental lines to improve the efficiency of common bean improvement programs.

Identification of novel genes potentially involved in somatic embryogenesis in chicory (Cichorium intybus L.).

BackgroundIn our laboratory we use cultured chicory (Cichorium intybus) explants as a model to investigate cell reactivation and somatic embryogenesis and have produced 2 chicory genotypes (K59, C15) sharing a similar genetic background. K59 is a responsive genotype (embryogenic) capable of undergoing complete cell reactivation i.e. cell de- and re-differentiation leading to somatic embryogenesis (SE), whereas C15 is a non-responsive genotype (non-embryogenic) and is unable to undergo SE. Previous studies [1] showed that the use of the β-D-glucosyl Yariv reagent (β-GlcY) that specifically binds arabinogalactan-proteins (AGPs) blocked somatic embryo production in chicory root explants. This observation indicates that β-GlcY is a useful tool for investigating somatic embryogenesis (SE) in chicory. In addition, a putative AGP (DT212818) encoding gene was previously found to be significantly up-regulated in the embryogenic K59 chicory genotype as compared to the non-embryogenic C15 genotype suggesting that this AGP could be involved in chicory re-differentiation [2]. In order to improve our understanding of the molecular and cellular regulation underlying SE in chicory, we undertook a detailed cytological study of cell reactivation events in K59 and C15 genotypes, and used microarray profiling to compare gene expression in these 2 genotypes. In addition we also used β-GlcY to block SE in order to identify genes potentially involved in this process.ResultsMicroscopy confirmed that only the K59, but not the C15 genotype underwent complete cell reactivation leading to SE formation. β-GlcY-treatment of explants blocked in vitro SE induction, but not cell reactivation, and induced cell wall modifications. Microarray analyses revealed that 78 genes were differentially expressed between induced K59 and C15 genotypes. The expression profiles of 19 genes were modified by β-GlcY-treatment. Eight genes were both differentially expressed between K59 and C15 genotypes during SE induction and transcriptionally affected by β-GlcY-treatment: AGP (DT212818), 26 S proteasome AAA ATPase subunit 6 (RPT6), remorin (REM), metallothionein-1 (MT1), two non-specific lipid transfer proteins genes (SDI-9 and DEA1), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), and snakin 2 (SN2). These results suggest that the 8 genes, including the previously-identified AGP gene (DT212818), could be involved in cell fate determination events leading to SE commitment in chicory.ConclusionThe use of two different chicory genotypes differing in their responsiveness to SE induction, together with β-GlcY-treatment represented an efficient tool to discriminate cell reactivation from the SE morphogenetic pathway. Such an approach, together with microarray analyses, permitted us to identify several putative key genes related to the SE morphogenetic pathway in chicory.

The same treatment for transgenic shoot regeneration elicits the opposite effect in mature explants from two closely related sweet orange (Citrus sinensis (L.) Osb.) genotypes

In citrus, production of mature transgenic plants belonging to different genotypes is an important biotechnological objective. In the present study, we tried to genetically transform and regenerate mature plants from the economically important Navelina sweet orange cultivar by using the procedure previously established for the genetically close Pineapple sweet orange variety. The use of BAP at 3 mg l−1 promoted efficient shoot organogenesis in Pineapple as expected, but not in Navelina. Furthermore, different effects were observed when the auxin α-naphtalene acetic acid (NAA) was added to BAP-containing regeneration media. Although NAA addition at 0.5 mg l−1 enhanced cambial callus formation, number of shoots and their elongation in Navelina, the contrary effect was observed in Pineapple. Moreover, transformation efficiency in Navelina rose from 0 to 3% but declined from 6 to 0% in Pineapple, indicating that BAP and BAP + NAA exerted the opposite effect in transgenic shoot regeneration from two closely related cultivars. This suggests that small changes in the procedure could induce drastic alterations in regeneration and even increase the likelihood of obtaining transformants from non-responsive genotypes. Moreover, the vigour of the starting plant material and the addition of kanamycin as selective agent were determining for the generation of mature sweet orange transgenic plants.

Efficacité de l’interféron pégylé associé à la ribavirine en cas de co-infection VIH-VHC: Résultats de l’essai Apricot

Until the publication in 2004 of the Apricot, ACTG 5071, and ANRS Ribavic trials, data about the treatment of patients coinfected with HIV and HCV were sparse. The international Apricot study included 868 HIV-HCV-coinfected patients naive of all HCV treatments. They were randomized into 3 groups for 48 weeks of hepatitis C treatment by peginterferon alpha-2a + ribavirin, or peginterferon alpha-2a + placebo, or interferon alpha-2a + ribavirin. Six months after treatment stopped, sustained virologic response (the principal efficacy criterion, intention-to-treat analysis) was observed in 40% of patients treated by peginterferon + ribavirin (29% for the nonresponsive genotype 1, and 62% for genotypes 2 and 3), 20% of those receiving peginterferon + placebo, and 12% of those in the group of nonpegylated interferon + ribavirin. This study also validated the positive and negative predictive values of viral load analyzed at 12 weeks of treatment; it was best for patients in genotypes 2 and 3. The factors associated with the best virologic response were a non-1 genotype and a low HCV viral load (< 800,000 IU/mL). As pointed out in the guidelines of the last European consensus conference on coinfection, the combination of peginterferon + ribavirin is currently the reference treatment for chronic hepatitis C. It should also be the preferred treatment for patients with HIV-HCV coinfection.

Characterization of proteins secreted during maize microspore culture: arabinogalactan proteins (AGPs) stimulate embryo development

To study molecules secreted from cultured plant cells that promote development, maize microspores were transferred into culture and the conditioned media were collected over time and analysed. Electrophoresis indicated that both non-glycosylated and glycosylated proteins including arabinogalactan proteins (AGPs) appeared in the medium and their concentration increased during the time of culture. The development of embryos was correlated with the presence of specific extracellular proteins, using an experimental system based on a tunicamycin inhibition test. In addition, a precise protein analysis was conducted using MALDI-TOF and ESI-MS-MS techniques. These approaches have allowed the identification of 5 other types of proteins: a cell wall invertase, two thaumatin isoforms, one 1-3 beta-glucanase and two chitinase isoforms. Altogether these experiments and results open ways for research aimed at understanding which molecules stimulate embryo formation. Moreover, AGPs may be used to stimulate the development of microspores (pollen embryogenesis) prepared from non-responsive genotypes.

LOWLAND RICE GENOTYPES EVALUATION FOR PHOSPHORUS USE EFFICIENCY

ABSTRACT Phosphorus (P) deficiency is the most yield-limiting factor in lowland rice production in Inceptisols of Brazil. A greenhouse experiment was conducted to evaluate 12 genotypes of lowland rice (Oryza sativa L.) using an Inceptisol (Typic Haplaquepts). The P treatments were: low (0 mg P kg−1), medium (100 mg P kg−1), and high (400 mg P kg−1). Significant (P<0.01) genotypes differences in P-use efficiency were found. On the basis of P-use efficiency, genotypes were classified as efficient and responsive, efficient and non-responsive, non-efficient and responsive, and non-efficient and non-responsive. From a practical point of view, efficient and responsive and efficient and non-responsive genotypes are the most desirable ones. Among the 12 genotypes tested, none were found to be efficient and responsive and genotypes CNA7553, CNA7591, CNA7601, and Aliança were found to be efficient and non-responsive. Among the yield components, panicle length and harvest index were significantly affected by P levels and genotypes and P and genotypes interactions were significant for these two parameters. However, panicle number was significantly influenced only by P treatment. Among the yield components, panicle number, harvest index, and panicle length were significantly (P<0.01) related to grain yield.

Chronic Hepatitis C Treatment: A Review

Chronic Hepatitis C Treatment: A Review

Plant regeneration capacity of mesophyll protoplasts from Brassica napus and related species

Protoplasts from a total of thirty-six genotypes of Brassica species – B. napus, B. campestris (syn. B. rapa), B. juncea, and three distant relatives, Orychophragmus violaceus, Isatis indigotica and Xinjiang wild rape – were analysed for shoot regeneration using a feeder culture system. With the exception of B. campestris and Xinjiang wild rape, some genotypes of all the species could regenerate plants with high efficiency (above 20% of isolated calli initiating shoots). Several genotypes with high regeneration ability were elite breeding lines. Culture conditions as well as genotype had a significant impact on shoot regeneration frequency. In particular, silver nitrate added to the regeneration medium at doses of 6 and 30 μM improved shoot regeneration frequency to 25.4% and 52.2% of isolated calli, respectively, compared to 7.3% percent shoot regeneration without silver nitrate in seven responsive genotypes. Addition of silver nitrate to the regeneration medium also induced shoot regeneration in non-responsive genotypes. Intact plants could be obtained within three months from protoplast isolation in the regenerative genotypes using the current culture system. Advantages of mesophyll protoplasts as compared to protoplasts isolated from hypocotyls for genetic manipulation in Brassica species are discussed.

Identification of a 32-kDa anther marker protein for androgenic response in maize, Zea mays L.

Variations in the whole anther protein pattern have been investigated in a highly androgenic maize hybrid during the inductive pretreatment for androgenesis. It was found that a 32-kDa protein (MAR32) is induced and accumulates in the anthers during cold pretreatment of the tassel. A positive correlation between the rate of embryo formation via anther culture and the level of this protein after 7 days of cold treatment was observed. In addition, the in vivo synthesis of this protein by cold-pretreated anthers was demonstrated. Different responsive and non-responsive genotypes were also evaluated, and the accumulation of MAR32-like protein was only observed in certain responsive genotypes. The results suggest that the protein MAR32 is a marker for a form of androgenic responsiveness in maize.