High genetic diversity and lack of pronounced population structure in five species of sympatric Pacific eels

Understanding the population structure of tropical anguillids residing in the Pacific is vital for their conservation management. Here, the population genetic structure of five sympatric freshwater eels (Anguilla marmorata Quoy & Gaimard, A. megastoma Kaup, A. obscura Steindachner, A. reinhardtii Günther and A. australis Richardson) across 11 western South Pacific (WSP) islands was investigated based on partial nucleotide sequences of the mtDNA control region and the nuclear GTH2b genes of 288 newly collected samples jointly with existing sequences. WSP anguillids are characterised by overall high levels of genetic diversity. Both mtDNA and nuclear sequences provided no evidence for distinct geographic clines or barriers in any of the species across the WSP. The occurrence of admixed individuals between A. marmorata and A. megastoma was confirmed, and a new possible occurrence of a further species was revealed (A. interioris Whitley on Bougainville Island). All species showed evidence for demographic population growth in the Pleistocene, and a subsequent population reduction for A. megastoma. Common spawning grounds and mixing of larvae by ocean currents could promote the lack of pronounced isolation by distance, a finding that has significant implications for the future management of anguillids in the area.     

印迹法用于鉴定番茄青枯病抗性的初步研究

对7个番茄品种和2个对照材料接种青枯病菌后用印迹法检验，并与常规田间抗病性鉴定法进行比较，结果表明植株在距离根茎部向上25cm处青枯病菌的检出率高、低与田间植株的感、抗性基本对应，据此认为在不利于青枯病发生的低温季节，印迹法可用于抗病性鉴定。     

Development of chloroplast DNA markers in Japanese Imperata cylindrica

Imperata cylindrica (cogongrass) is one of the most invasive grass weeds found worldwide. In Japan, this grass grows as three climate types: cool temperate (CT), common (CM) and subtropical (ST). An early flowering (E) type has been also reported. Among them, the CM type is large and most invasive. Recent global warming may cause the extension of distribution of the CM type to northern parts of Japan and may allow hybrids to form between the CM and CT or E types. The hybrids sometimes show heterosis and this leads to new weed problems. Distinguishing between the hybrids and parents on a morphological basis is difficult. We investigated polymorphisms of eight cpDNAs to enable distinction between the ecotypes and the hybrids. Fourteen haplotypes were detected in 33 Japanese clones, based on variations in eight cpDNA regions. Based on three substitutions in the psbA–matK spacer, the ORF170 intron1, the trnL(UAA) intron–trnF(GAA) spacer and indels in the trnL(UAA) intron–trnF(GAA) spacer, the haplotypes were clustered into three phylogenetic groups: I, IIa and IIb, which corresponded with the CM and ST, E and CT types, respectively. The polymorphism in the cpDNA therefore enables us to distinguish among the ecotypes and is useful for prediction of the range expansion of the CM type.     

Incidence of spinal injuries in migratory Yellowstone cutthroat trout captured at electric and waterfall‐velocity weirs

The South Fork Snake River (Idaho, USA) supports a native Yellowstone cutthroat trout (YCT) population Oncorhynchus clarkii bouvieri (Richardson) threatened by non‐native rainbow trout O. mykiss (Walbaum). Electric weirs prevent rainbow trout passage into YCT spawning tributaries but may cause spinal injuries. YCT captured at electric weirs on Palisades and Pine Creeks and a control waterfall‐velocity weir on Burns Creek were X‐rayed in 2012 and 2013 to estimate spinal injury rates. Electrical pulse frequency was increased from 2012 to 2013 at the Palisades (from 11.5 to 20 Hz) and Pine weirs (13–20 Hz), and spinal injury rates were found to increase from 11.3 to 21.3% at Palisades and from 6.5 to 14.7% at Pine, while Burns injury rates remained constant (4.5% in 2012 and 6.0% in 2013), suggesting the electric weirs caused spinal injuries in YCT. Lower pulse frequencies may minimise YCT spinal injury but still prevent rainbow trout from accessing YCT spawning tributaries.     

Morphological and genetic comparison between naturally produced smolts of Atlantic salmon,brown trout and their hybrids

Morphological characters were compared between smolts (standard length 110–220 mm) of Atlantic salmon Salmo salar L., anadromous brown trout Salmo trutta L. and their hybrids captured in River Driva, western Norway. Morphological discrimination between S. salar, S. trutta and their hybrids was correct for 93% of the individuals (correct form was determined genetically). Morphological discrimination of hybrids was incorrect with 9.1% (n = 7) classified as S. salar and 1.3% (n = 1) as S. trutta, suggesting that the hybrids were morphologically more similar to S. salar than S. trutta despite a bias towards S. trutta mothers (7 of 8 cases). The largest morphological differences were found in head (notably maxilla length) and caudal peduncle morphology. Hybrids between S. salar and S. trutta had the longest pectoral and pelvic fins. This indicates that precise discrimination based on morphological traits can be made between S. salar, S. trutta and their hybrids.     

Gibberellic Acid + 2,4-D Improves Seed Quality in Hordeum vulgare L. ×H. bulbosum L. Crosses

Doubled haploid production from crosses between barley (Hordeum vulgare L.) and H. bulbosum L. is a well established technique for inducing homozygosity. One problem which occurs using certain barley cultivars is premature seed degeneration. In this paper, a post-pollination spray of gibberellic acid and 2,4-dichlorophenoxyacetic acid that delays the onset of senescence is described. The technique improved the number of high quality seeds to more than 75% of the seed set. This improvement should result in increased survival of embryos for culture and subsequent plant regeneration.     

Failure in an interspecific cross between Solanum khasianum Clarke and Solanum mammosum L.

Summary Attempts to obtain a successful interspecific cross between Solanum khasianum Clarke and Solanum mammosum L. were unsuccessful, and the probable reasons for this failure were investigated. A reduced number of viable pollen grains and low receptivity of the stigmas of S. mammosum L. and heterostyly in both species are the probable reasons for the failure of the attempted interspecific crosses between S. khasianum Clarke and S. mammosum L.