Targeted identification of association between cotton fiber quality traits and microsatellite markers

Primitive and exotic accessions of cotton are potential sources of favorable alleles for genetic improvement, enriching diversity in the genetically constricted gene pool of elite cultivars. Three exotic accessions of cotton (MDN101, MDN063 and MDN257), collected from different parts of Central America and converted to day-neutral flowering; and four elite cultivars (PD94042, DES56, PMHS200 and Acala Maxxa) representing the US cotton gene pool were used as parents to create experimental populations. The corresponding F₂ and F_2:3 progenies of these populations were grown in two successive years (i.e., some in 2011–2012, some in 2012–2013) and phenotypes were scored in both F₂ and F_2:3 progenies in all 3 years (2011–2012–2013). These populations were screened with 113 polymorphic microsatellite markers selected from “hotspots” for fiber quality quantitative trait loci in the cotton genome and single marker analyses were performed to identify significant associations of the markers with six fiber quality traits. A total of 134 nominal marker-trait associations were identified, among which 15 were significant after Bonferroni correction for multiple comparisons. In 67 of 134 nominal associations and 4 of 15 significant associations, the exotic parents contributed favorable alleles to multiple backgrounds and for multiple traits, in addition to the traits for which they were selected. These results indicate that utilization of exotic and wild accessions of cotton is useful in introducing favorable alleles into the cultivated cotton gene pool for genetic improvement.     

A quantitative trait locus on chromosome 5B controls resistance of <Emphasis Type="Italic">Triticum turgidum</Emphasis> (L.) var. <Emphasis Type="Italic">diccocoides</Emphasis> to Stagonospora nodorum blotch

Stagonospora nodorum blotch (SNB) is an important foliar disease of durum wheat (Triticum turgidum var. durum) worldwide. The combined effects of SNB and tan spot, considered as components of the leaf spotting disease complex, result in significant damage to wheat production in the northern Great Plains of North America. The main objective of this study was the genetic analysis of resistance to SNB caused by Phaeosphaeria nodorum in tetraploid wheat, and its association with tan spot caused by Pyrenophora tritici-repentis race 2. The 133 recombinant inbred chromosome lines (RICL) developed from the cross LDN/LDN(Dic-5B) were evaluated for SNB reaction at the seedling stage under greenhouse conditions. Molecular markers were used to map a quantitative trait locus (QTL) on chromosome 5B, explaining 37.6% of the phenotypic variation in SNB reaction. The location of the QTL was 8.8 cM distal to the tsn1 locus coding for resistance to P. tritici-repentis race 2. The presence of genes for resistance to both SNB and tan spot in close proximity in tetraploid wheat and the identification of molecular markers linked to these genes or QTLs will be useful for incorporating resistance to these diseases in wheat breeding programs.     

Prevalence and clonal diversity of Campylobacter jejuni from dairy farms and urban sources

AIM: To investigate the role of free-living animals such as spar- rows, rodents and flies as potential reservoirs of Campylobacter spp on a dairy farm, and to assess the genetic diversity among Campylobacter isolates from the farm and an urban source.

METHODS: A total of 290 samples (bovine, passerine and ro- dent faeces, and whole flies) were collected from a large com- mercial dairy farm in the Manawatu district in New Zealand, and from faeces from urban sparrows in a nearby city. Other samples collected from the dairy farm included five from silage, two from aprons worn by workers during milking, two from workers' boots and two from water in troughs in a paddock. Isolates of thermophilic Campylobacter spp were identified mor- phologically and phenotypically and further characterised mo- lecularly using pulsed-field gel electrophoresis (PFGE) and the restriction enzyme SmaI.

RESULTS: Campylobacter jejuni was the only Campylobacter species isolated from all samples. The highest prevalence was found in faeces from dairy cows (54%), followed by faeces from sparrows from the urban area (40%) and the farm (38%), and from rodents (11%) and whole flies (9%). Other samples from the farm environment such as silage, trough water, and work- ers' aprons and boots were also positive for C. jejuni. Of the 22 restriction patterns obtained, seven were common to more than one source.

CONCLUSIONS: Cattle, sparrows, rodents and flies are po- tential reservoirs of C. jejuni on dairy farms. Identical clones of C. jejuni carried by cattle, sparrows, flies and rodents prob- ably indicate a common source of infection. The high level of asymptomatic carriage of C. jejuni by healthy dairy cows could be sufficient to maintain infections within the dairy farm sur- roundings via environmental contamination.     

A novel urea coated with pine oleoresin for enhancing yield and nitrogen uptake by maize crop

A study was conducted with maize in Vertisol, Inceptisol, Alfisol and Aridisol to evaluate the efficacy of the pine oleoresin coated urea fertilizers (coated with 1.25, 2.50, 3.75 and 5.00% pine oleoresin). Significant increase in biomass yield was observed in all the soils when urea was coated with pine oleoresin at 3.75% or more. All the pine oleoresin coated urea in Inceptisol and Aridisol; and 3.75% and 5% pine oleoresin coated urea in Vertisol and Alfisol significantly increased nitrogen (N) uptake as compared to uncoated urea. Nitrogen use efficiency increased from 19.34% to 32.80% in Vertisol, 13.06% to 28.27% in Alfisol, 13.87% to 23.86% in Inceptisol and 10.68% to 20.23% in Aridisol, as a result of coating urea with pine oleoresin. Thus the results indicate that there is a beneficial effect of coating urea with pine oleoresin with respect to yield, N uptake and use efficiency in maize crop.     

印度东北地区一种极频危和特有树种(Ilex khasiana Pork.)再生生态学及种群现状

在5个典型自然种群Mylliem(种群1)、Upper Shillong(种群2)、Shillong Peak(种群3)、Laitkor(种群4)和Nongpiyur(种群5)中,详细研究了冬青树(Ilex khasiana)种群结构和再生生态学,旨在探究种群结构和再生能力的影响因素.在全光照(100%),中等光照(50%)和低光照(30%)三种光强度条件下,实验观察表明:在中等和低光照条件下的种苗成活率和生长状态好于在高光照条件下的种苗成活率和生长状态.成年树种群(≥5cm dbh)的密度直径分布揭示了一种再生种群的典型特征.对植被的破坏和人类其他干扰导致森林树冠疏开使光照增强,造成自然种群(L khasiana)幼苗的高死亡率.本研究结果对制定适当的物种保护措施有重要价值.     

Landraces-potential treasure for sustainable wheat improvement

Genetic Resources and Crop Evolution - Agricultural production is facing serious threat from various biotic and abiotic stresses specifically under climatic challenges. It is becoming increasingly...     

Forest fragmentation and regrowth in an institutional mosaic of community, government and private ownership in Nepal

This study analyzes forest change in an area of Nepal that signifies a delicate balance between sustaining the needs and livelihood of a sizable human population dependent on forest products, and an effort to protect important wildlife and other natural resources. The study area, a portion of the Chitwan valley district of Nepal, represents what may be becoming a common institutional mosaic in many countries of the world who have a population reliant on forest products for their livelihood: (1) a national park; (2) a designated park buffer involving participatory forest management programs; (3) scattered patches of designated community forest; and (4) large areas of adjacent landscape made up of mostly private landholdings under agricultural practices. Utilizing Landsat images from 1989 and 2000, we analyze land cover change in each of these management zones using landscape ecology metrics and quantifying proportional distributions of land cover categories. Our results show significant differences in terms of land cover dynamics and landscape spatial pattern between these land ownership classes. These findings indicate that community-based institutions (participatory management programs in the park buffer and the designated community forests) are capable of halting or even reversing trends in deforestation and forest fragmentation.     

Association mapping of quantitative resistance to Phaeosphaeria nodorum in spring wheat landraces from the USDA National Small Grains Collection

Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, is a destructive disease of wheat (Triticum aestivum) found throughout the United States. Host resistance is the only economically feasible option for managing the disease; however, few SNB-resistant wheat cultivars are known to exist. In this study, we report findings from an association mapping (AM) of resistance to P. nodorum in 567 spring wheat landraces of diverse geographic origin. The accessions were evaluated for seedling resistance to P. nodorum in a greenhouse. Phenotypic data and 625 polymorphic diversity array technology (DArT) markers have been used for linkage disequilibrium (LD) and association analyses. The results showed that seven DArT markers on five chromosomes (2D, 3B, 5B, 6A, and 7A) were significantly associated with resistance to P. nodorum. Genetic regions on 2D, 3B, and 5B correspond to previously mapped quantitative trait loci (QTL) conferring resistance to P. nodorum whereas the remaining QTL appeared to be novel. These results demonstrate that the use of AM is an effective method for identifying new genomic regions associated with resistance to P. nodorum in spring wheat landraces. Additionally, the novel resistance found in this study could be useful in wheat breeding aimed at controlling SNB.     

Bioactive benzoxazinoids in rye bread are absorbed and metabolized in pigs

Recently, bioactive benzoxazinoids were discovered in cereal grains and bakery products. In this study, we studied the uptake, distribution, and metabolism of these secondary metabolites using a pig model. Twelve benzoxazinoid compounds and their 4 transformation products were quantified in the pigs' diets and biofluids using high-performance liquid chromatography coupled to electrospray ionization triple quadrupole mass spectrometry. The 2-β-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-glc) was the most dominant benzoxazinoid (232 nmol/g DM) seconded by the double-hexose derivative of DIBOA (provisionally characterized here as DIBOA-glc-hex) in the rye-based diet. DIBOA-glc (derived from the diet and intestinal deglycosylation of DIBOA-glc-hex) was apparently reduced to 2-β-D-glucopyranosyloxy-1,4-benzoxazin-3-one (HBOA-glc), the most dominant benzoxazinoid in the blood (829 nmol/L). The benzoxazinoid compounds were excreted in the urine, with HBOA-glc (18 μmol/L) as a major metabolite. In this study, we determined for the first time the bioavailability of dietary benzoxazinoids that have high digestibility, distribution, and metabolism in mammals. These findings could be a milestone for the exploitation of healthful and pharmacological properties of benzoxazinoids.     

Pork quality attributes associated with bilateral carcass variation

The objective of this study was to identify bilateral differences in pork carcass quality as influenced by single leg shackling and suspension of electrically stunned pigs. Fifty-six Genepacker x EB market barrows (118 kg) were rendered unconscious and insensible to pain via electrical stimulation. Pigs were then shackled and suspended by the right hind leg before exsanguination and remained suspended until scalding. Initial (45-min) pH values of the LM at the 10th to 11th rib interface were different (P = 0.016); shackled side loins possessed a greater i.m. pH than those loins associated with the free side of the carcass (6.26 vs. 6.10). At 24 h postmortem, loins from the shackled side had lower (P < 0.001) L* values than loins from the free side in both the sirloin (53.08 vs. 57.61) and blade (54.61 vs. 57.09) regions. Additionally, b* values were greater (P < 0.001) for loins from the shackled side than loins from the free side in the center (13.81 vs. 13.01) and blade (14.72 vs. 13.68) regions, and in the blade region, a* values were greater (P < 0.001) in the LM from the shackled side than loins from the free side (7.37 vs. 6.26). Moreover, LM chops of loins from the shackled side that were aged 21 d were rated less (P < 0.05) tough (2.74 vs. 3.95) and more (P < 0.05) juicy (4.24 vs. 3.19) than chops from the free-hanging side. However, these differences were not evident after 41 d aging. From the results of this study, it can be concluded that bilateral differences exist within the LM of a pork carcass and that these differences are likely associated with the single-leg shackling and suspension of electrically stunned pigs.