Divergent evolution of rice blast resistance <Emphasis Type="Italic">Pi54</Emphasis> locus in the genus <Emphasis Type="Italic">Oryza</Emphasis>

Background

The rice blast resistance gene Pi54 was cloned from Oryza sativa ssp. indica cv. Tetep, which conferred broad-spectrum resistance against Magnaporthe oryzae. Pi54 allelic variants have been identified in not only domesticates but also wild rice species, but the majority of japonica and some indica cultivars lost the function.

Results

We here found that Pi54 (Os11g0639100) and its homolog Os11g0640600 (named as #11) were closely located on a 25 kbp region in japonica cv. Sasanishiki compared to a 99 kbp region in japonica cv. Nipponbare. Sasanishiki lost at least six genes containing one other R-gene cluster (Os11g0639600, Os11g0640000, and Os11g0640300). Eight AA-genome species including five wild rice species were classified into either Nipponbare or Sasanishiki type. The BB-genome wild rice species O. punctata was Sasanishiki type. The FF-genome wild rice species O. brachyantha (the basal lineage of Oryza) was neither, because Pi54 was absent and the orientation of the R-gene cluster was reversed in comparison with Nipponbare-type species. The phylogenetic analysis showed that #11gene of O. brachyantha was on the root of both Pi54 and #11 alleles. All Nipponbare-type Pi54 alleles were specifically disrupted by 143 and 37/44?bp insertions compared to Tetep and Sasanishiki type. In addition, Pi54 of japonica cv. Sasanishiki lost nucleotide-binding site and leucine-rich repeat (NBS–LRR) domains owing to additional mutations.

Conclusions

These results suggest that Pi54 might be derived from a tandem duplication of the ancestor #11 gene in progenitor FF-genome species. Two divergent structures of Pi54 locus caused by a mobile unit containing the nearby R-gene cluster could be developed before domestication. This study provides a potential genetic resource of rice breeding for blast resistance in modern cultivars sustainability.

     

Genotypic effects on the variation of wood quality and growth traits in plantation forest made by cutting cultivars of Japanese cedar

We studied the effect of genotypes of planting stocks regarding the variation of the modulus of elasticity of tree trunks on standing trees (trunk-MOE), tree height (TH), and diameter at breast height (DBH) in a 19-year-old Japanese cedar plantation made with root cuttings. Trunk-MOE was assessed nondestructively using a tree-bending method. Genotypes of individual trees were detected using the random amplified polymorphic DNA (RAPD) technique. RAPD analysis revealed that the sampled plantation consisted of 14 genotypes. Genotypic effects on DBH and TH were unclear, and there was no significant difference among genotypes. This result indicated that an acquired variation should have more influence than an inherited variation on DBH and TH. For trunk-MOE, there were significant differences among the four largest genotypes at the 5% level. However the coefficient of variation in trunk-MOE of each genotype ranged from 7.5% to 26.8%. It seems reasonable to assume that the wide variation in trunk-MOE in a sampled plantation may depend on the environmental effect within a clone as well as on the genetic origin of clones. We therefore conclude that the use of multiple planting stocks from different cuttings for which the wood quality is unknown contributed strongly to the wide variation in trunk-MOE in the plantation of Japanese cedar.     

Comparison of behavior, physical condition and performance of laying hens in four molting methods

The objective of the present study was to evaluate the welfare level of hens in four molting methods by comparing their behavior, physical condition and performance. In total, 96 White Leghorn layers (72 weeks of age) were used. The four molting methods consisted of 10 days of feeding and the first 3 days of water withdrawal WFW); 10 day feed withdrawal (WF) followed by ad libitum access to a layer diet from day 11, 28 days of restricted feeding (RF) and 28 days without withdrawing their feed (NW). The RF and NW hens were fed a low energy diet. The WFW and WF hens showed two clear phases of behavior during the 10‐day fasting period. Explorative and stereotyped behavior increased for WFW and WF hens just after their fast. Standing‐resting then increased for WFW and WF hens while lying‐resting decreased. In contrast, RF and NW hens did not show clear behavioral changes during the 28‐day molt period. The weight loss of the NW hens was more gradual compared with the other three methods. No significant differences were seen in any productive trait among the four methods during the postmolt period. In conclusion, the welfare level of RF and NW, especially NW, was higher compared with WFW and WF.     

Effect of flutianil on the morphology and gene expression of powdery mildew

Flutianil, a fungicide effective only on powdery mildew, was previously reported to affect the host cell''s haustorial formation and nutrient absorption. Studies were conducted to investigate flutianil''s primary site of action on Blumeria graminis morphology using transmission electron microscope (TEM) observation and RNA sequencing (RAN-seq) techniques. TEM observation revealed that flutianil caused the extra-haustorial matrix and fungal cell wall to be obscured, without remarkable changes of other fungal organelles. RNA-seq analysis indicated that, unlike other powdery-mildew fungicides, flutianil did not significantly affect the constantly expressed genes for the survival of B. graminis. Genes whose expression is up- or downregulated by flutianil were found; these are the three sugar transporter genes and various effector genes, mainly expressed in haustoria. These findings indicate that the primary site of action of flutianil might be in the haustoria.     

Oxygen isotopic compositions of asteroidal materials returned from Itokawa by the Hayabusa mission

Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.     

Compliance rate of livestock vehicles with welfare standards, and behavior of feeder cattle at loading ramp

The objective of the present study was to assess cattle welfare during transportation. Vehicle inspection and observation of cattle behavior during loading operations were conducted at two major livestock markets (T and M) in Japan. Market T provided young feeder cattle (Wagyu and cross‐bred aged 6.8–9.0 months) mainly for regions farther than 1500 km. Market M provided young cattle (Wagyu aged 6.6–11.2 month) and calves (crossbred and Holstein aged 0.7–1.5 month) for nearby regions within 500 km. Market T had loading platforms 1.0 m high, whereas market M had partial allocation of platforms and forced most transporters to load cattle from the ground. Vehicles were inspected according to the welfare standards for beef cattle of the RSPCA. Number of vehicles inspected was 36 and 31 in markets T and M, respectively. Cattle hesitations (kneeling down, slipping, balking, backing down, turning around, jumping and eliminating) were observed at the loading ramp. Vehicles inspected at the markets complied with most requirements of the welfare standards, but non‐compliance was found in two requirements: in market M, 71.0% of vehicles had the loading ramp at a >20% incline, whereas 17.1% of vehicles did in market T (P < 0.001). Slope of the loading ramp was steeper in market M than in market T (33.9 ± 17.3% vs. 14.9 ± 8.9%, P < 0.001). Market M had higher proportion of vehicles that did not comply with the requirement ‘Both loading ramps and tail boards must be appropriately designed and covered with litter, to prevent animals from falling off or slipping’ compared with market T (83.9% vs. 17.1%, P < 0.001). Higher frequencies were observed in two kinds of hesitating behavior in market M than in market T (both P < 0.01): mean frequencies (times/head) of slipping and balking were 1.3 ± 1.2 and 2.0 ± 1.8 in market M, and 0.2 ± 0.2 and 0.7 ± 0.5 in market T, respectively. Steeper loading ramp was correlated with higher frequencies of kneeling down (r = 0.53), slipping (r = 0.59), balking (r = 0.45) and backing down (r = 0.42) (all P < 0.05).     

Effects of testosterone on rat placental development

We investigated the morphological effects of testosterone on placental development in a rat model of polycystic ovarian syndrome (PCOS). Testosterone propionate (TP), which was subcutaneously administered to pregnant rats with 5 mg/animal from gestation day (GD) 14 to GD 18, induced a maternal weight reduction without mortality or clinical signs from GD 19 onwards. A decrease in fetal and placental weight, an increase in intrauterine growth retardation (IUGR) rates, and histological changes in the placenta were observed on GD 21 but not on GD15 or 17. Histopathologically, on GD 21, the trophoblast septa thickened, and the maternal sinusoids were narrowed in the labyrinth zone, resulting in a small placenta. Additionally, the placental weight, thickness, and histological morphology in the labyrinth zone on GD 21 in the TP-treated group were nearly identical to those on GD 17 in the control and TP-treated groups. Therefore, it was assumed that the testosterone-induced small placenta was induced in association with the developmental inhibition of the fetal part of the placentas from GD 17 onwards.     

The <Emphasis Type="Italic">Arabidopsis NST3/SND1</Emphasis> promoter is active in secondary woody tissue in poplar

Wood biomass is one of the promising future materials for biofuels with no competing food uses. However, the higher cost to produce bioethanol from wood feedstocks is regarded as a priority issue. Genetic engineering techniques have been proposed to enhance the quality and quantity of wood materials to overcome the cost problem. Although many genetically engineered trees with applicable traits such as low lignin, a high syringyl to guaiacyl ratio and high cellulose content are generated, ectopic expression of an effector gene under a constitutive promoter can sometimes induce untoward side effects on plant growth and development. Our recent study demonstrated that AtNST3/SND1 promoter of Arabidopsis thaliana is a candidate tool for driving a potent activator to enhance wood biomass production in poplar without any growth retardation. However, the tissue- and cell-dependent activity of the promoter remains to be elucidated. In the present study, we generated transgenic poplar expressing AtNST3/SND1promoter::GUS to examine in detail the activity of the AtNST3/SND1 promoter. Histochemical analysis revealed that the promoter was predominantly active in secondary woody tissue. Our result indicates that the AtNST3/SND1 promoter is an option for expressing an effector gene to modify secondary cell wall components and wood biomass.