摘要:

Knowledge of natural variation among ecotypes and recombinant inbred lines ofArabidopsis thalianaL. Heynh for season‐long water‐use efficiency (WUE, moles of carbon accumulated per mole of water used) is useful in the design of experiments to understand the genetic control of this phenomenon. Water‐use efficiency among 31 container‐grownArabidopsisecotypes ranged from a high of 2.40 to a low of 1.86 mg/g (grams of dry aerial biomass per gram of water used). Genetic variance for WUE was observed among 80 F5recombinant inbred lines (RILs) derived from a cross between the highest (Lip‐0) by the lowest (Edi‐0) ecotype. The heritability of WUE was calculated as 0.18 ± 0.07. The mean WUE for the ten highest and ten lowest RILs was 2.42 and 1.05 mg/g, respectively. A significant difference was observed in the composition of stable isotopes of plant carbon (δ13C) between the mean of the ten highest (‐31.23±) and the mean of the ten lowest (‐31.96±) RILs based on WUE. Characterization of the 80 RILs provides a structured population for further genetic and physiologic study of WUE.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15580.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Leaf spacing and aboveground growth were monitored in saplings of ten species in a range of light environments in a Panamanian lowland humid forest. One‐ to 2‐m‐tall individuals of the chosen species had intermediate to large leaves on stems with few or no branches. Saplings in high light environments grew faster in height and produced more biomass per unit leaf area than shaded saplings for all species. These growth responses involved morphological plasticity with greater extension per unit biomass increment increasing the height growth rate of gap‐grown saplings and greater biomass allocation to leaves decreasing the whole plant light compensation point in shade. The relative performance of the species also varied across the light gradient and was related to differences in leaf lifespan and specific leaf mass. Light‐demanding species grew as rapidly in shade as shade‐tolerant species, but the shorter leaf lifespan of the former necessitates higher production rates to maintain a given leaf area, largely excluding light‐demanders from shaded understory locations. Height growth rate was positively correlated with leaf spacing for each species, and differences between species in the height growth rate‐internode length relationship were related to interspecific differences in specific leaf mass. Thus, sapling growth histories may be inferred from their morphologies.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15581.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Among various potential causes of rarity, one explanation could be that a rare species has more narrow physiological tolerances to important environmental variables than does a widespread species. To test this hypothesis photosynthetic performance as a function of irradiance and temperature was compared for the rare cedar glade endemicEchinacea tennesseensisand its widespread prairie congenerE. angustifoliafollowing various light and soil moisture preconditioning regimes. Although the species differed in some morphological characteristics such as specific leaf area, both species demonstrated similar photosynthetic light‐response curves on a leaf area basis, with low to moderate photosynthetic capacity. Thus no photosynthetic differences were found that could account for the contrasting geographic distributions of the endemic species and its widespread congener.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15582.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

The distribution of genetic variation within and among plant populations is influenced by both contemporary and historical factors. I used isozyme analysis of band phenotypes to examine genetic structure in the rare prairie forbSilene regia.Relationships between current‐day population size, isolation, and phenotypic variation were assessed for 18 populations in two regions with differing postglacial history. Western populations from unglaciated southern Missouri and Arkansas were more genetically diverse based on the Shannon‐Weaver index (H) and a polymorphic index than were more eastern populations. These differences may be due to loss of variation with repeated founding of new populations in previously glaciated sites in Indiana and Ohio. Within the western region, population size was not significantly correlated with genetic variation. In the east, size was correlated with Shannon‐Weaver diversity. There was no relationship between variation and isolation in either region, but eastern populations were slightly more differentiated. Greater among‐population differentiation and the demonstrated connection between population size and variation in the eastern sites may reflect lower levels of interpopulation gene flow in the fragmented remnant prairies of Indiana and Ohio.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15583.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

An image analysis system was used to calculate the surface area and volume of the submerged leaves of seven species ofMyriophyllum.We separated the species into two categories based on their distribution and habitat differences and compared their surface area, volume, dry mass, specific leaf area, and surface to volume ratios. The geographic location and habitat of the species explained the greatest percentage of total variance for these variables when compared by analysis of variance. A leaf shape analysis was performed by regressing surface area with volume for each species. Interspecific comparisons of leaf shape were made using analysis of covariance. Fundamental interspecific differences in submerged leaf shape, associated with differences in their geographic distributions and habitats, are explained as adaptations for different nutrient uptake regimes.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15584.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Historical and current ecological and genetic factors were examined in western popultions ofEriocaulon kornickianumto determine the cause and consequence of rarity in this disjunct species and to assess its extinction vulnerability. Reproductive biology was examined, which included an examination of breeding systems, seed set, and pollen viability. Recruitment into and maintenance of the populations was evaluated using seed bank estimates. A disturbance study was conducted that examined the effects of competing vegetation and associated species, and included clipping, burning, and artificial seeding. Enzyme electrophoresis was used to measure genetic variation in an effort to examine gene flow within and among populations. Many factors are contributing to the decline of the western populations of this species and include an annual or weak perennial life history, no vegetative reproduction, low seed set, little seed bank contribution to population growth and maintenance, genetic homogeneity, a restricted habitat, and poor competitive abilities. Continuing studies of genetic variation are being used to examine historical factors that may have resulted in a genetic bottleneck observed in the western populations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15585.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

The aleurone of RB‐3shrunken‐2 (sh2) maize kernels is deficient in α‐amylase activity during germination, but exogenous applications of gibberellic acid (GA3) (0.001–10 μm) induced low levels of activity. The highest activity was measured in the aleurone of kernels treated with 10 μmGA3(14,600 ± 945 units), but was lower than untreatedStarchy(Su) aleurone tissues (35,280 ± 5,010 units). On isoelectric focusing gels, no α‐amylase isozymes were detected in the untreatedsh2 aleurone using starch zymograms or immunoblots, but the 1.0 and 10 μmmm GA3treatments induced nearly all the isozymes (eight to ten) present in theSualeurone. There was a very low level of α‐amylase mRNA in the untreatedsh2 aleurone, an intermediate level in the 1.0 μmGA3‐treatedsh2 aleurone, and the highest level in the untreatedSualeurone. On the confocal microscope, the 1.0 μmGA3‐treated aleurone cells had enhanced levels of cytoplasmic membranes and RNA compared to untreatedsh2 aleurone cells. The 1.0 μmGA3treatment also induced shoot elongation in thesh2 seedlings. The data demonstrate that thesh2 aleurone is deficient in its function to produce α‐amylases, and exogenous GA3can partially restore cell function in thesh2 kernels.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15586.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

In higher plants, plastids and mitochondria are the predominant carriers of extrachromosomal genetic information. There is interplay between the plastids, the mitochondria, and the nuclear genome. In soybean,Glycine max(L.) Merr., both nuclearly and maternally inherited chlorophyll‐deficient mutants have been described. Conditional lethality previously was reported in soybean when maternally inherited chlorophyll‐deficient mutant (Genetic Type T275) was crossed with nuclearly inherited yellow foliar malate dehydrogenase null mutants (Genetic Types T253 and T323). Our objective was to test for conditional lethality when maternally inherited yellow foliar mutants T278, T314, T315, T316, T319, and T320 were female parents and nuclearly inherited yellow foliar malate dehydrogenase null mutants T253 and T323 were male parents. Our results indicated conditional lethality in the F2generation when any of the six cytoplasmically inherited yellow foliar mutants were female parents and either T253 or T323 were male parents. The physiological nature of conditional lethality is not known. Data indicate a common basis in soybean for conditional lethality among the cytoplasmically inherited yellow foliar mutants when crossed with the nuclearly inherited yellow foliar malate dehydrogenase null mutants. No interactions were observed between cytoplasmically inherited or nuclearly inherited green seed embryo mutants as female parents and either T253 or T323 as male parents.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15587.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

The population genetic structure and spatial genetic structure of the dioecious aquatic macrophyteVallisneria americanawas examined near Turkey Island in the Detroit River in late summer of 1991. The density and distribution of male, female, and vegetative ramets was determined for three transects parallel, and three transects perpendicular to the island, at mean water depths of 38–306 cm. A strong male‐biased sex ratio was observed in shallow water, while sex ratios became increasingly female‐biased, and plant density increased, at greater water depths. Cellulose acetate gel electrophoresis was used to characterize the allozyme phenotype of each ramet that had been screened for seven enzyme systems. Overall, 91 allozyme phenotypes were identified. A single allozyme phenotype accounted for 33%–55% of all the ramets (depending on the transect), indicating extensive regional vegetative growth. However, the population as a whole displayed high genetic diversity (HT= 0.3403), with most of the diversity occurring within transects (Hs= 0.3297) rather than between transects (DST= 0.0106). The possible factors accounting for the high small‐scale genetic diversity of this clonal aquatic plant species are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15588.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

This study describes the genetic structure and provides estimates of mating system parameters in three natural populations ofProsopis velutinaWoot. in southeastern Arizona.Fstatistics derived from isozyme data revealed the presence of both interpopulation and intrapopulation genetic differentiation. This population structure is discussed in relation to the ecological history of these populations that invaded the grasslands sites from adjacent riparian areas within the last 90 years, and possible modes of seed dispersal. The multilocus estimation program MLT of Ritland (Journal of Heredity8: 235–237, 1990) was used to provide estimates ofts, tm, and the fixation index (F) of the maternal parents. Average estimates oftsranged from 0.591 to 0.912. Estimates oftmranged from 0.609 to 1.004, and averaged 0.758. The difference betweentmandts, which provides a measure of biparental inbreeding, averaged 0.058. This last result, together with significant heterogeneity found in pollen allele frequencies, suggests that a family structure has developed in the populations. A negativeFvalue for one of the populations suggests selection against homozygotes between the seedling stage and maturity.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15589.x

出版商:Wiley    

年代:1994

数据来源: WILEY