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1.
Theor Appl Genet ; 108(6): 993-1001, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15067384

ABSTRACT

To analyze quantitative trait loci (QTLs) affecting flooding tolerance and other physiological and morphological traits in Echinochloa crus-galli, a restriction fragment length polymorphism (RFLP) map was constructed using 55 plants of the F(2) population ( E. crus-galli var. praticola x E. crus-galli var. formosensis). One hundred forty-one loci formed 41 linkage groups. The total map size was 1,468 cM and the average size of linkage groups was 35.8 cM. The average distance between markers was 14.7 cM and the range was 0-37.2 cM. Early comparisons to the genetic maps of other taxa suggest appreciable synteny with buffelgrass ( Pennisetum spp.) and sorghum ( Sorghum spp.). One hundred ninty-one F(2) plants were used to analyze QTLs of flooding tolerance, plant morphology, heading date, number of leaves, and plant height. For flooding tolerance, two QTLs were detected and one was mapped on linkage group 24. Other traits, including plant morphology, heading date, number of leaves, and plant height were highly correlated. Three genomic regions accounted for most of the mapped QTLs, each explaining 2-4 of the significant marker-trait associations. The high observed correlation between the traits appears to result from QTLs with a large contribution to the phenotypic variance at the same or nearby locations.


Subject(s)
Chromosome Mapping , Echinochloa/genetics , Phenotype , Polymorphism, Restriction Fragment Length , Quantitative Trait Loci/genetics , Crosses, Genetic , DNA Primers , Disasters , Pennisetum/genetics , Sorghum/genetics , Species Specificity , Synteny/genetics
2.
Bioresour Technol ; 91(2): 141-4, 2004 Jan.
Article in English | MEDLINE | ID: mdl-14592742

ABSTRACT

Some switchgrass (Panicum virgatum L.) cultivars originating in the northern USA show limited late-summer and fall growth when grown in more southerly locations despite adequate temperature and moisture. Our objective was to determine the effects of low-light photoperiod extension on the dry matter yield of switchgrass cultivars originating from contrasting latitudes. Seedlings of the four cultivars (Cave-in-Rock, 'Caddo', 'Kanlow', and 'Alamo') were grown for 100 d in a greenhouse in winter under ambient (11.2-12.2 h) and extended (18 h) photoperiods. Photoperiod extension was with 7 micromol m(-2) s(-1) photosynthetic photon flux density. Cultivars responded differently to photoperiod extension (P<0.05). Large increases in dry matter yield at extended photoperiods were observed in Cave-in-Rock (+98%) and Caddo (+129%). The dry matter yield of Kanlow increased by 31%, whereas dry matter yield of the southernmost cultivar Alamo was not affected by photoperiod extension. Yield increases for Cave-in-Rock and Caddo were associated with increased tiller number and weight. A reversal of dormancy for some cultivars with a photoperiodic signal verified that dormancy was not simply a result of a low radiant input.


Subject(s)
Photoperiod , Poaceae/growth & development , Geography , Light , Poaceae/physiology , United States
3.
Genome ; 46(2): 304-13, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12723046

ABSTRACT

Linkage analyses increasingly complement cytological and traditional plant breeding techniques by providing valuable information regarding genome organization and transmission genetics of complex polyploid species. This study reports a genome map of buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.). Maternal and paternal maps were constructed with restriction fragment length polymorphisms (RFLPs) segregating in 87 F1 progeny from an intraspecific cross between two heterozygous genotypes. A survey of 862 heterologous cDNAs and gDNAs from across the Poaceae, as well as 443 buffelgrass cDNAs, yielded 100 and 360 polymorphic probes, respectively. The maternal map included 322 RFLPs, 47 linkage groups, and 3464 cM, whereas the paternal map contained 245 RFLPs, 42 linkage groups, and 2757 cM. Approximately 70 to 80% of the buffelgrass genome was covered, and the average marker spacing was 10.8 and 11.3 cM on the respective maps. Preferential pairing was indicated between many linkage groups, which supports cytological reports that buffelgrass is a segmental allotetraploid. More preferential pairing (disomy) was found in the maternal than paternal parent across linkage groups (55 vs. 38%) and loci (48 vs. 15%). Comparison of interval lengths in 15 allelic bridges indicated significantly less meiotic recombination in paternal gametes. Allelic interactions were detected in four regions of the maternal map and were absent in the paternal map.


Subject(s)
Alleles , Chromosome Mapping , Genetic Linkage , Genome, Plant , Pennisetum/genetics , Crosses, Genetic , Diploidy , Genes, Plant , Genetic Markers , Heterozygote , Meiosis , Poaceae/genetics , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , Polyploidy
4.
Plant Mol Biol ; 32(6): 1085-92, 1996 Dec.
Article in English | MEDLINE | ID: mdl-9002607

ABSTRACT

Limited emphasis has been given to the molecular study of apomixis, an asexual method of reproduction where seeds are produced without fertilization. Most buffelgrass (Pennisetum ciliare (L.) Link syn = Cenchrus ciliaris L.) genotypes reproduce by obligate apomixis (apospory); however, rare sexual plants have been recovered. A modified differential display procedure was used to compare gene expression in unpollinated ovaries containing ovules with either sexual or apomictic female gametophytes. The modification incorporated end-labeled poly(A)+ anchored primers as the only isotopic source, and was a reliable and consistent approach for detecting differentially displayed transcripts. Using 20 different decamers and two anchor primers, 2268 cDNA fragments between 200 and 600 bp were displayed. From these, eight reproducible differentially displayed cDNAs were identified and cloned. Based on northern analysis, one cDNA was detected in only the sexual ovaries, two cDNAs in only apomictic ovaries and one cDNA was present in both types of ovaries. Three fragments could not be detected and one fragment was detected in ovaries, stems, and leaves. Comparison of gene expression during sexual and apomictic development in buffelgrass represents a new model system and a strategy for investigating female reproductive development in the angiosperms.


Subject(s)
Gene Expression Regulation, Plant , Poaceae/genetics , Cloning, Molecular , DNA, Complementary/genetics , Genotype , Molecular Sequence Data , Poaceae/growth & development , Poaceae/physiology , Polymerase Chain Reaction , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Plant/genetics , RNA, Plant/metabolism
5.
Adolescence ; 15(57): 91-7, 1980.
Article in English | MEDLINE | ID: mdl-7369013

ABSTRACT

A questionnaire listing 31 personal, social and family changes believed stressful to adolescents was administered to 207 subjects aged eleven to eighteen. They were asked to rate the items on a scale of one to five to indicate how "upsetting" they believed the event was. They were also asked to indicate how many of the events they had actually experienced. The Adolescent Life Change Event Scale developed from this data is shown. It is recommended that the questionnaire be given to a much larger sample of adolescents from other socioeconomic, racial and cultural backgrounds before the final weightings are assigned to the scale. Once this has been done, the scale can be used to study relationships between life stress events and illness or other manifestations of stress in adolescents.


Subject(s)
Life Change Events , Psychological Tests , Adolescent , Female , Humans , Male , Stress, Psychological/psychology
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