Molecular diversity in Indian sugarcane cultivars as revealed by randomly amplified DNA polymorphisms   总被引：5，自引：0，他引：5  

N.V. Nair  A. Selvi  T.V. Sreenivasan  K.N. Pushpalatha 《Euphytica》2002,126(2):219-225

Genetic diversity in 28 prominent Indian sugarcane varieties cultivated under a wide range of agroclimatic conditions, was studied using 25 RAPD markers. The mean genetic distance among the 28 varieties was only 29.31%, implying that a large part of the genome is similar among the varieties. This probably arises from the lack of parental diversity, with few clones which are themselves related, contributing to the parentage of these varieties. The parentage of the varieties did not contribute significantly to the clustering pattern. Varieties belonging to the same parentage were grouped under different clusters while varieties from different parentages were grouped under the same cluster. The tropical and subtropical identities of the varieties also did not contribute to the clustering pattern as individual clusters included varieties from both tropics and subtropics. This shows that genetically similar varieties are present in both the regions. Among the varieties, Co 7717 was found to be totally distinct and divergent from rest of the varieties. The study reveals the limited genetic base of the current Indian commercial varieties and the need to diversify the genetic base by using new sources from the germplasm. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Identification of soybean strains resistant to Xanthomonas campestris pv. glycines     

Arun Sharma  P. M. Nair  S. E. Pawar 《Euphytica》1993,67(1-2):95-99

Summary Soybean germplasm was screened for resistance to bacterial pustule disease. The etiological agent, Xanthomonas campestris pv. glycines, was isolated from the leaves of field grown soybean in Maharashtra, India. The screening of soybean stocks was carried out by excised leaf inoculation method. A differential susceptibility to the pathogen was observed in the tested stocks. Two stocks P-4-2 and P-169-3 were found to be completely resistant to the pathogen and displayed an incompatible reaction. Four cultivars, EC-34160, Bragg, Kalitur and PK-472 displayed moderate resistance and the remaining stocks were susceptible to the attack of the pathogen. The stocks P-4-2 and P-169-3 remained resistant even to a high concentration of 10⁹ colony forming units (cfu)/ml of the pathogen.  相似文献   

Cloning of a gene encoding LRR protein and its validation as candidate gall midge resistance gene,Gm4, in rice     

Dhanasekar Divya  Kudapa Himabindu  Suresh Nair  Jagadish S. Bentur 《Euphytica》2015,203(1):185-195

  相似文献   

Seed set and seedling variation in greater yam (Dioscorea alata L.)     

K. Abraham  S. G. Nair  M. T. Sreekumari  M. Unnikrishnan 《Euphytica》1986,35(2):337-343

Summary A high degree of fruit and seed set was obtained in Dioscorea alata L. by hand pollination. The sexual progeny was studied in comparison with the clonal plants. In general, the seedlings were poor in growth vigour, flowering and tuber production but the variations observed in the different characters were unprecedented, indicating scope for efficacious genetic improvement in this vegetatively propagated crop.  相似文献   

Genome classification of banana cultivars from South India using IRAP markers   总被引：8，自引：0，他引：8  

Ashalatha?S.?Nair  Chee?How?Teo  Trude?Schwarzacher  Pat?Heslop?HarrisonEmail author 《Euphytica》2005,143(3):285-290

Summary The banana cultivars are originated from the intra- and inter-specific hybridization of two wild diploid species, Musa acuminata Colla and Musa balbisiana Colla, contributing the A and B genomes, respectively. They are classified into genomic groups by scoring morphological features. Molecular markers provide a quick and reliable system of genome characterization and manipulation in breeding lines. In the present study a PCR based molecular marker specific for B genomes is been reported. The IRAP primer, designed based on the LTR sequence of banana Ty3-gypsy-like retroelement (Musa acuminata Monkey retrotransposon, AF 143332), was used to identify the B genome in the banana cultivars. Further a primer pair designed from B specific bands of Musa balbisiana `Pisang Gala' was used to classify AAB and ABB cultivars in the collection. Among the 36 cultivars tested with this primer, the B specific band was absent in the AA and AAA cultivars (except in one AAA and AAB cultivar) but present in all other AB, AAB and ABB cultivars. Among the triploid AAB/ABB, the PCR products with B specific primers showed restriction pattern polymorphism with AluI. In ABB genomes the band intensity was high whereas low intensity band observed in AAB genomes. Four cultivars reported to have the ABB genome showed a pattern similar to AAB, and one cultivar reported to have AAA genome showed a pattern similar to ABB genome, suggesting missampling or misidentification. The primers used in this study are useful to identify the presence of B genome in banana cultivars, and band intensity may be a preliminary indicator of ploidy level of the B genome but needs further studies with competitive PCR for clarification. These authors contributed equally in this paper.  相似文献   

Nitrogen mineralization in a pecan (Carya illinoensis K. Koch)–cotton (Gossypium hirsutum L.) alley cropping system in the southern United States     

Samuel C. Allen  Shibu Jose  P. K. R. Nair  Barry J. Brecke  Vimala D. Nair  Donald A. Graetz  Craig L. Ramsey 《Biology and Fertility of Soils》2005,41(1):28-37

Information on temporal and spatial patterns of N mineralization is critical in designing tree-crop mixed systems that could maximize N uptake while minimizing N loss. We quantified N mineralization rates in a pecan (Carya illinoensis K. Koch)–cotton (Gossypium hirsutum L.) alley cropping system in northwestern Florida with (non-barrier) and without tree-crop belowground interactions (barrier separating the root systems of pecan and cotton). Monthly rates of mineralization were estimated using buried bag incubations over a 15-month period. In addition, seasonal mineralization rates and cotton lint yield on soils supplied with two sources of N—inorganic fertilizer and organic poultry litter—were assessed. Results indicated that temporal variations in net NH₄ and NO₃ accumulation and mineralization rates were driven primarily by environmental factors and to a lesser degree by initial soil NH₄ and NO₃ levels. Mineralization varied by belowground interaction treatment during the initial growing season, when the non-barrier treatment exhibited a higher mineralization rate than the barrier treatment, likely due to reduced nutrient uptake by cotton in the non-barrier or a higher degree of immobilization in the barrier treatment. Mineralization during the second growing season was similar for both treatments. Source of N had no effects on N transformation in the soil. Lint yield reductions were observed in the non-barrier treatment during both years compared to the barrier treatment, likely due to interspecific competition for water. Yield differences between treatments in the second growing season were likely compounded by a diminishing pre-study fallow effect. Source of N was found to have a significant effect on cotton yield, with inorganic fertilizer resulting in 39% higher lint compared to poultry litter in the barrier treatment.  相似文献   

Insecticidal fatty acids and triglycerides from Dirca palustris.   总被引：3，自引：0，他引：3  

R S Ramsewak  M G Nair  S Murugesan  W J Mattson  J Zasada 《Journal of agricultural and food chemistry》2001,49(12):5852-5856

Five compounds, 1-5, were isolated from the seed hexane extract of Dirca palustris. Compounds 1-3 were triglycerides, and 4 and 5 were linoleic and oleic acids, respectively. Compounds 1-3 were not biologically active; however, 4 (linoleic acid) and 5 (oleic acid) were insecticidal against fourth instar Aedes aegyptii larvae and exhibited potent feeding deterrent activity against neonate larvae of Helicoverpa zea, Lymantria dispar, Orgyia leucostigma, and Malacosoma disstria.  相似文献   

Fine structure constant defines visual transparency of graphene   总被引：1，自引：0，他引：1  

Nair RR  Blake P  Grigorenko AN  Novoselov KS  Booth TJ  Stauber T  Peres NM  Geim AK 《Science (New York, N.Y.)》2008,320(5881):1308

There are few phenomena in condensed matter physics that are defined only by the fundamental constants and do not depend on material parameters. Examples are the resistivity quantum, h/e2 (h is Planck's constant and e the electron charge), that appears in a variety of transport experiments and the magnetic flux quantum, h/e, playing an important role in the physics of superconductivity. By and large, sophisticated facilities and special measurement conditions are required to observe any of these phenomena. We show that the opacity of suspended graphene is defined solely by the fine structure constant, a = e2/hc feminine 1/137 (where c is the speed of light), the parameter that describes coupling between light and relativistic electrons and that is traditionally associated with quantum electrodynamics rather than materials science. Despite being only one atom thick, graphene is found to absorb a significant (pa = 2.3%) fraction of incident white light, a consequence of graphene's unique electronic structure.  相似文献   

Gonadotropin-releasing hormone: one polypeptide regulates secretion of luteinizing and follicle-stimulating hormones   总被引：9，自引：0，他引：9  

A V Schally  A Arimura  A J Kastin  H Matsuo  Y Baba  T W Redding  R M Nair  L Debeljuk  W F White 《Science (New York, N.Y.)》1971,173(4001):1036-1038

A polypeptide isolated from porcine hypothalami stimulates the release of both luteinizing hormone and follicle-stimulating hormone from the pituitaries of several species. This polypeptide has been structurally identified as (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH(2) and synthesized. The natural and synthetic materials share biological properties. It appears that this peptide represents the hypothalamic hormone regulating the secretion of both luteinizing hormone and follicle-stimulating hormone.  相似文献   

Synthetic Juvenile Hormone: Induction of Sex Pheromone Production in Ips confusus     

Boriden JH  Nair KK  Slater CE 《Science (New York, N.Y.)》1969,166(3913):1626-1627

Topical application of 25, 50, or 100 micrograms of 10,11-epoxy-farnesenic acid methyl ester in peanut oil induced male Ips confusus to produce sex pheromone in the hindgut Malpighian tubule region. Twenty-four hours aftertreatment of male beetles with 100 micrograms of hormone, their hindgut Malpighian tubule extract was more attractive to female beetles in a laboratory bioassay than was extract from males producing pheromone naturally in ponderosa pine logs.  相似文献