Sweet potato foot rot, first confirmed in Okinawa in 2018, is spreading to southern Kyushu and causing serious yield losses. A previous study showed that integrating soil treatment with trifloxystrobin wettable powder, seedling treatment with benomyl wettable powder, and foliar sprays with fluazinam and triflumizole wettable powders and basic copper sulfate is highly effective. Here we evaluated the efficacy of this integrated system and effects on yields using two new varieties resistant to foot rot and the main variety Chura-Koi-Beni in Okinawa. We evaluated three trifloxystrobin systems: system 1 (described above), a reduced-spray version of system 1 (system 2), and system 2 with copper sulfate applications (system 3). Disease incidence on Chura-Koi-Beni was lower in all three systems than in the conventional system, and yields were statistically similar to or greater than in the conventional. The new varieties also showed low levels of aboveground symptoms, indicating that combining them with the trifloxystrobin systems can further enhance disease suppression. Overall, the three trifloxystrobin-based systems in Okinawa Prefecture were effective against this disease; even the reduced spray (system 2) can be effective, and system 3 has the potential to achieve control equal to or greater than with system 2. In addition, combining resistant varieties can provide even better disease control.
Males of the chafer Protaetia ishigakia (Fairmaire) (Coleoptera: Scarabaeidae) were observed to fly toward, hover around and land on flowers of the epiphytic orchid Luisia teres (Thumberg) Blume (Orchidaceae). On a flower, a male chafer inserted his head deep into the base of the flower column, where pollinia transferred between stigma of the flower and frons of the male. When solvent extract of the flower was applied on a cotton ball, male chafers landed on it and some of them showed pseudocopulatory behavior involving extrusion of the proboscis and/or copulatory organ. No such behaviors were observed in females. A chemical releasing these behaviors in males was identified as ( R )-2,3-dihydroxypropyl isovalerate (( R )-2,3-DHPiV). Male chafers were observed to land frequently on the cotton balls treated with synthetic ( R )-2,3-DHPiV, whereas a 95:5 blend of ( R )- and ( S )-enantiomers was more attractive than pure ( R )-enantiomer. 2,3-DHPiV was strongly suggested to be a sex-pheromone component of P. ishigakia . These results that the flower of L. teres chemically deceived males of P. ishigakia while the flower secrete honey as an award in response of stimulation by chafer’s proboscis were quite like to the interaction between the orchid L. teres and the congeneric chafer P. pryeri pryeri (Janson).
To clarify the effects of traditional Okinawan vegetable extracts on the activation of immunocompetent cells, we prepared methanol extracts from lyophilized powders of Crepidiastrum lanceolatum Nakai (hosoba-wadan), Peucedanum japonicum Thunb. (botan-bofu) and Artemisia indica Willd. var. orientalis (Damp.) H. Hara (nishi-yomogi). We examined nitric oxide and cytokine production and phagocytosis of macrophage-like J774.1 cells following stimulation with extracts as activation indices. Moreover, we investigated the effect of the hosoba-wadan extract on tumor growth in tumor-bearing mice. IL-6 and TNF-alpha production and incorporation of microbeads in the 3 mu g/mL hosoba-wadan extract group were significantly higher than in the other groups. We also observed that intraperitoneal administration (30 mg/mouse) of the hosoba-wadan extract significantly suppressed tumor growth compared with the saline group. Moreover, the hosoba-wadan extract resulted in significant increases of serum TNF-alpha and IFN-gamma concentrations in the mice. These results suggest that the hosoba-wadan extract activated immunocompetent cells and enhanced host immunity.
Marker-assisted selection (MAS) using DNA markers linked to a single or a few quantitative trait loci (QTL) with low genetic contribution has not been effectively and practically applied due to the significant loss of target offspring. High sugar content (soluble solids content, SSC) is an important breeding goal for fresh pineapple in Japan. We investigated the efficiency of MAS performed before primary phenotypic selection for a first-fruited F1 pineapple population of 'Yugafu' x 'Yonekura' for a single QTL with 11.6% genetic contribution controlling SSC. Four genotypes at this QTL were detected by a SNP marker and segregated 1:1:1:1. Statistical analysis was performed using logSSC values. The logSSC means in the four genotypes were significantly separated, the distributions within each genotype were close to normal distribution, and the variances within genotypes were not significantly different. The target offspring (> 17 Brix%) in this population was estimated to be 5.3%. Among four genotypes in the QTL, MAS of selecting the genotype with the highest mean SSC and MAS of selecting the top two genotypes for mean SSC were called 25% MAS and 50% MAS, respectively. Selection efficiency (Se) was defined as the ratio of the target offspring selected by MAS to the target offspring present in the initial population before MAS. Se was 0.51 and 0.81 for 25% and 50% MAS, respectively, resulting in a loss of 49% and 19% of the target offspring. To compensate for this loss and obtain the same number of target offspring achieved by conventional phenotypic selection without MAS, the initial population needed to be increased by x(1/Se), which was defined as the effective MAS scale (EMSS). The EMSS was 1.95 and 1.24 for 25% MAS and 50% MAS, respectively, and the population sizes after MAS were 0.49 and 0.62 times the population without MAS, respectively, indicating a small difference between the 25% and 50% MAS. Considering this result and the cost of MAS, 50% MAS was recommended over 25% MAS for the population. These results showed that efficient MAS without reducing the number of target offspring was achievable by expanding the initial population size by EMSS.
