Evolution of Parallel Spindles Like genes in plants and highlight of unique domain architecture#

<p>Abstract</p> <p>Background</p> <p>Polyploidy has long been recognized as playing an important role in plant evolution. In flowering plants, the major route of polyploidization is suggested to be sexual through gametes with somatic chromosome number (2<it>n</it>). <it>Parallel Spindle1 </it>gene in <it>Arabidopsis thaliana </it>(<it>AtPS1</it>) was recently demonstrated to control spindle orientation in the 2nd division of meiosis and, when mutated, to induce 2<it>n </it>pollen. Interestingly, <it>AtPS1 </it>encodes a protein with a FHA domain and PINc domain putatively involved in RNA decay (i.e. Nonsense Mediated mRNA Decay). In potato, 2<it>n </it>pollen depending on parallel spindles was described long time ago but the responsible gene has never been isolated. The knowledge derived from <it>AtPS1 </it>as well as the availability of genome sequences makes it possible to isolate potato <it>PSLike </it>(<it>PSL</it>) and to highlight the evolution of <it>PSL </it>family in plants.</p> <p>Results</p> <p>Our work leading to the first characterization of <it>PSLs </it>in potato showed a greater <it>PSL </it>complexity in this species respect to <it>Arabidopsis thaliana</it>. Indeed, a genomic <it>PSL </it>locus and seven cDNAs affected by alternative splicing have been cloned. In addition, the occurrence of at least two other <it>PSL </it>loci in potato was suggested by the sequence comparison of alternatively spliced transcripts.</p> <p>Phylogenetic analysis on 20 <it>Viridaeplantae </it>showed the wide distribution of <it>PSLs </it>throughout the species and the occurrence of multiple copies only in potato and soybean.</p> <p>The analysis of PSL^FHAand PSL^PINcdomains evidenced that, in terms of secondary structure, a major degree of variability occurred in PINc domain respect to FHA. In terms of specific active sites, both domains showed diversification among plant species that could be related to a functional diversification among <it>PSL </it>genes. In addition, some specific active sites were strongly conserved among plants as supported by sequence alignment and by evidence of negative selection evaluated as difference between non-synonymous and synonymous mutations.</p> <p>Conclusions</p> <p>In this study, we highlight the existence of PSLs throughout <it>Viridaeplantae</it>, from mosses to higher plants. We provide evidence that <it>PSLs </it>occur mostly as singleton in the analyzed genomes except in soybean and potato both characterized by a recent whole genome duplication event. In potato, we suggest the candidate <it>PSL </it>gene having a role in 2<it>n </it>pollen that should be deeply investigated.</p> <p>We provide useful insight into evolutionary conservation of FHA and PINc domains throughout plant PSLs which suggest a fundamental role of these domains for PSL function.</p

Effect of Cassava Processing Effluent on Soil Properties, Growth and Yield of Maize (Zea mays L.) in South Eastern Nigeria.

A study, comprising a survey, greenhouse and field experiments was conducted to examine the effect of Cassava Processing Effluent (CPE) on soil chemical properties, maize growth performances and grain yield. In the survey, soil samples were taken (0-15 and 15 – 30cm) of CPE contaminated and non contaminated areas of rural cassava processing depots. Serial dilutions of CPE collected from these depots (80, 60, 40, 20, and 0% (water only) were made and used to water potted maize plants for 30 days and field-sown maize for 120 days. The survey showed that soil pH, exchangeable potassium (K) and sodium (Na) were 4, 40 and 53% respectively, greater in uncontaminated than in contaminated soil. Calcium (Ca), Magnesium (Mg), available phosphorus (P) and organic matter increased significantly (p < 0.05) in CPE contaminated soil by 20, 9, 10 and 8%, respectively when compared with uncontaminated soil. Results of greenhouse and field experiments showed that all maize growth performances and grain yield were best when dilutions were between 20 and 40% (effluent in water). Mineralization of nitrogen (N) was greatly enhanced in the soil where CPE was disposed of when compared with NH4-N and NO3- N contents of uncontaminated soil. Since only traces of hydrogen cyanide (HCN) were analyzed in the soil at the end of the experiments (within recommended safe level of 5 mg kg-1) indicating that CPE is highly degradable.Keywords: Cassava processing effluent, Soil properties, Hydrogen cyanide, growth, yield, maize, Southeastern Nigeria

X-Chromatin (Drumstick) Status of a Male West African Dwarf (WAD) Goat (Buck) with Unilateral Cryptorchidism: A Case Report

A unilateral cryptorchid buck was screened for drumstick. Blood smears on microscope slides stained with Leishman, and observed under immersion oil light microscope revealed absence of drumsticks; thus indicated that the buck was an efficient male, with good potentialities for fertility. Therefore unilateral cryptorchids are not infertile and may be used for reproduction. Keywords: X-chromatin, drumstick, buck, testis, goat, cryptorchidismSahel Journal of Veterinary Sciences Vol. 5 (1) 2006 pp. 25-2

Genotype by Environment (G x E) Modeling of the Variable Initiation of Parthenocarpy sensu stricto in Musa: Elucidation of the Environmental Components of Variable Expressivity of Parthenocarpy in a Facultative Apomictic Musa acuminata Subspecies Microcarpa Model System

To better understand the genome by environment (G x E) interactions that need to be accommodated in order to better predict hybrid performance for a high breeding value vegetative parthenocarpy trait sensu stricto. An analysis of the possible environmental signals contributing to the variability of a vegetative parthenocarpy trait sensu stricto via the genome x environment initiation of a genetic lesion that temporally, developmentally and systematically results in abortion of a parthenocarpic developmental regime was performed utilizing Musa acuminata accession Borneo as a model plant. We examined the effect of the variable and potentially modulating environmental signals, and performed a dissection of the genetic components of expressivity and penetrance in the vegetative parthenocarpy in Borneo, utilizing 180 apomictic progeny planted at different developmental ages in duplicate at each of two ecoregional zones. A total of 2,160 floral rachis from 720 mats of Borneo were measured for their subsequent expressivity and penetrance for vegetative parthenocarpy across individual flowers produced from a single vegetative mat, across local duplicate mats, and across ecoregional zones. The results of our study have produced a predictive G x E Model for expressivity of vegetative parthenocarpy in Musa, with validation of this model by a variety of statistical and probabilistic methods. Since expressivity of vegetative parthenocarpy to similar environmental signals have been identified across the monocot to dicot plants such as tomato, the generalized use of models such as presented in our study may have broader applicability to a wider range of crop plants

Apomixia em Manihot esculenta e em seus híbridos interespecíficos Apomixis in Manihot esculenta and in its interespecific hybrids

O objetivo deste trabalho foi estudar a citogenética e a morfologia do saco embrionário dos clones EB1 (Manihot esculenta Crantz) e EB12 (geração F3 de M. esculenta x M. glaziovii Muell), dos híbridos F1 e F2 de M. neusana Nassar x M. esculenta e da espécie silvestre M. neusana, para verificar o fenômeno da apomixia. Os óvulos foram analisados pelo método de clarificação. Foi verificada apomixia, do tipo apospórica, no clone EB12, no híbrido F2, e em M. neusana. Foi demonstrada a estrutura embriônica da mandioca; foram observados dois sacos embrionários no mesmo óvulo do híbrido F2.<br>The objective of this work was to study cytogenetic and morphology of the embryonic sac of clones EB1 (Manihot esculenta Crantz) and EB12 (F3of M. esculenta x M. glaziovii Muell), of F1 and F2 hybrids of M. neusana Nassar x M. esculenta and of the wild species M. neusana, to verify the phenomenon of apomixis. Ovules were observed by the clarification method. Aposporic apomixis was observed in the EB12 clone, in the F2 hybrid and in M. neusana. The embryonic structure of Manihot was demonstrated and two embryonic sac were observed in the same ovule of F2

Variability of soybean germplasm in relation to phosphorus uptake and use efficiency Variabilidade em germoplasma de soja para eficiência na absorção e utilização de fósforo

Plant efficiency for phosphorus uptake and utilization may contribute to improve crop yield potential in situations of low P availability. Twenty nine soybean [Glycine max (L.) Merr.] cultivars were evaluated and classified in relation to the response to phosphorus (P) levels in nutrient solution. P uptake and use efficiency were estimated by the variables: shoot and root dry matter (DM) yield, P-concentrations and contents in plant parts and P-efficiency index (EI). The experiment was conducted in a greenhouse, during 1999, at Campinas, State of São Paulo, Brazil. The experimental design consisted of randomized complete blocks, arranged in split-plots, with three replications. The main plots were the P levels in the nutrient solution (64.5; 129; 258 and 516 mmol L-1), and the subplots were the twenty-nine soybean cultivars, grouped according days to maturity. The plants were harvested at flowering, separated in shoots and roots for dry matter determination and chemical analysis. The analyses of variance indicated differences in plant responses to P-levels and cultivars. Multivariate analysis showed high correlation among the variables shoot-DM, total-DM and shoot P-concentration and P-efficiency index (EI). Cultivars were classified in efficient-responsive (ER)-- 'IAC-1', 'IAC-2', 'IAC-4', 'IAC-5', 'IAC-6', 'IAC-9', 'Sta. Rosa' and 'UFV-1'; efficient-non-responsive (ENR) -- 'IAC-7', 'IAC-11', 'IAC-15', 'S. Carlos' and 'Cristalina'; inefficient-responsive (IR) -- 'IAC-8', 'IAC-10', 'IAC-14', 'Bossier' and 'Foscarin'; and inefficient-non-responsive (INR) -- 'IAC-12', 'IAC-13', 'IAC-16', 'IAC-17', 'IAC-18', 'IAC-19', 'IAC-20', 'IAC-22', 'Paraná', 'IAS-5' and 'BR-4'. The efficient-responsive soybean cultivars showed the highest values for shoot and total DM and EI, and the lowest shoot P-concentrations.<br>A eficiência da planta na absorção e utilização de fósforo em situação de baixa disponibilidade do nutriente pode contribuir para aumentar o potencial produtivo da cultura. Vinte e nove cultivares de soja [Glycine max (L.) Merr.] foram avaliados e classificados quanto à resposta a concentrações de fósforo (P) em solução nutritiva. Determinaram-se as variáveis relacionadas com a eficiência na absorção e utilização de P: produção de matéria seca (MS) da parte aérea e das raízes, teores de P nas partes das plantas e os índices de eficiência de utilização de P (IE). O experimento foi instalado em casa de vegetação em Campinas, em 1999. Foi utilizado o delineamento em blocos ao acaso, em parcelas subdivididas com três repetições. As parcelas principais constituíram-se das concentrações de P na solução nutritiva (64,5; 129; 258 e 516 mmol L-1) e as subparcelas, dos vinte e nove cultivares de soja, agrupados de acordo com o ciclo. As plantas foram colhidas no florescimento, separadas em parte aérea e raízes para determinação da matéria seca e análise química de nutrientes. A análise de variância indicou diferenças nas respostas das plantas para concentrações de P e cultivares. A análise multivariada mostrou alta correlação entre a MS de parte aérea e MS-total com os teores de P na parte aérea e índices de eficiência de utilização de P (IE). Os cultivares foram classificados em eficientes e responsivos (ER) -- 'IAC-1', 'IAC-2', 'IAC-4', 'IAC-5', 'IAC-6', 'IAC-9', 'Sta. Rosa' e 'UFV-1'; eficientes não responsivos (ENR) -- 'IAC-7', 'IAC-11', 'IAC-15', 'S. Carlos' e 'Cristalina'; ineficientes responsivos (IR) -- 'IAC-8', 'IAC-10', 'IAC-14', 'Bossier' e 'Foscarin'; e ineficientes não responsivos (INR) -- 'IAC-12', 'IAC-13', 'IAC-16', 'IAC-17', 'IAC-18', 'IAC-19', 'IAC-20', 'IAC-22', 'Paraná', 'IAS-5' e 'BR-4'. Os cultivares eficientes e responsivos mostraram os maiores valores para MS de parte aérea, MS total e IE, e os menores teores de P na parte aérea