UBVRI photometry of Betelgeuse over 23 years since 1999

We report the results of our continuous UBVRI-band photometry of Betelgeuse from 1999 to 2022 using the same photometric system. There are two advantages in our observation: (1) we used a photodiode as a detector to avoid saturation, and (2) our data set includes U-band light curve, which is not widely observed in recent CCD photometries. Using our light curves, we conducted the periodicity analysis, and found ~405- and ~2160-day periods. We also discuss the tentative detection of a long-period variation over 20 years or longer. Finally, we discuss the peculiar variation of the U-B color index during the "Great Dimming" event between late 2019 and early 2020.Comment: 29 pages, 7 figures, 2 tables. Published in OEJV. Full tables available as table1.dat and table2.da

Development of transgenic male-sterile rice by using anther-specific promoters identified by comprehensive screening of the gene expression profile database ‘RiceXPro’

Because genomic selection is designed for the population breeding of allogamous species, a successive outcrossing system is required for efficient use of genomic selection in autogamous crops, such as Oryza sativa L. (rice). Transgenic and dominant male-sterility is a suitable tool for efficient outcrossing of autogamous crops. Though there have been some reports of dominant male-sterile rice developed using transgenic technology, the flowering habit was substandard. Here, to isolate promoters that, when linked to a lethal gene, induce dominant male-sterility while retaining a good flowering habit, we identified 38 candidate genes with anther-specific expression by using the ‘RiceXPro’ database. We then evaluated the abilities of the near-upstream regions of these genes to induce male-sterility when linked to the lethal gene barnase and introduced into the rice cultivar ‘Nipponbare’. Seven of the 38 promoters induced clear dominant male-sterility; promoters expressed in the later stage of anther development induced male-sterility while retaining better flowering habits when compared to ones expressed in the early stage. These seven promoters could potentially be used to facilitate development of an efficient outcross-based breeding system in rice

Development and characterization of transgenic dominant male sterile rice toward an outcross-based breeding system

Genomic selection is attracting attention in the field of crop breeding. To apply genomic selection effectively for autogamous (self-pollinating) crops, an efficient outcross system is desired. Since dominant male sterility is a powerful tool for easy and successive outcross of autogamous crops, we developed transgenic dominant male sterile rice (Oryza sativa L.) using the barnase gene that is expressed by the tapetum-specific promoter BoA9. Barnase-induced male sterile rice No. 10 (BMS10) was selected for its stable male sterility and normal growth characteristics. The BMS10 flowering habits, including heading date, flowering date, and daily flowering time of BMS10 tended to be delayed compared to wild type. When BMS10 and wild type were placed side-by-side and crossed under an open-pollinating condition, the seed-setting rate was <1.5%. When the clipping method was used to avoid the influence of late flowering habits, the seed-setting rate of BMS10 increased to a maximum of 86.4%. Although flowering synchronicity should be improved to increase the seed-setting rate, our results showed that this system can produce stable transgenic male sterility with normal female fertility in rice. The transgenic male sterile rice would promote a genomic selection-based breeding system in rice

Strictness of the Centrifugal Location of Bundle Sheath Chloroplasts in Different NADP-ME Type C4 Grasses

C4 plants have many attractive traits for crops, but their structural and functional relationships are complicated. C4 plants are different in bundle sheath cell (BSC) chloroplast location (centrifugal or centripetal) among species. The effects of light intensity on the centrifugal location of BSC chloroplasts were investigated in four grass species of NADP malic enzyme (NADP-ME) type (Zea mays, Echinochloa utilis, Sorghum bicolorand Eriachne aristidea)by light and electron microscopy. Furthermore, the degree of granal development was examined to investigate the relation between BSC chloroplast location and dependence of BSC chloroplasts on the reducing power of mesophyll cells. We investigated BSC chloroplast location grown under high intensity light (HL) (600 μ mol m-2s-1), low intensity light (LL) (2.5 μ mol m-2s-1) and dark conditions and counted the number of granal thylakoids per granum. Although BSC chloroplasts of maize maintained the centrifugal position under all light conditions, the centrifugal location of other species was disturbed under LL and in the dark. Granal development in BSC chloroplasts in the plants grown under HL was suppressed, although the suppression in Z maysand S. bicolorwas more prominent than in other two species. These findings indicate that there is a difference in the strictness of centrifugal location of BSC chloroplasts among NADP-ME type C4 grass species and the strictness had no relation to the degree of granal development in BSC chloroplasts

Expression of Photosynthesis-Related Genes during the Leaf Development of a C3 Plant Rice as Visualized by In Situ Hybridization

The expression of photosynthesis-related genes, rbcS (small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase) and cab (light-harvesting chlorophyll a/b-binding protein), in emerging rice leaves was examined. We performed in situ hybridization to visualize the spatial expression pattern of the photosynthesis-related genes. In the basal region of the leaf blade, which is the youngest region in a leaf blade of monocotyledonous plants, the expression of the genes was observed in both bundle sheath and mesophyll cells, while in the older middle and the oldest tip regions, the expression was only observed in mesophyll cells and not in bundle sheath cells. These results indicate that the expression of these photosynthesis-related genes is developmentally regulated and becomes mesophyll-specific in mature leaves. The expression of the photosynthesis-related genes in the lamina joint was also examined. These genes were not expressed in the lamina joint of immature leaves nor in the mature leaves. Therefore, the lamina joint was considered to be a photosynthetically inactive region

Effects of introduction of sorghum RbcS with rice RbcS knockdown by RNAi on photosynthetic activity and dry weight in rice

Rubisco is the key enzyme responsible for photosynthetic CO2 fixation. Previously, we succeeded to increase the catalytic rate (kcat) of Rubisco by the overexpression of sorghum C4-type Rubisco small subunit (RbcS) in rice. These Rubisco are present as a chimera of sorghum RbcS and rice RbcS. In this study, we introduced an RNAi construct for rice RbcS into a sorghum RbcS overexpression line (SS10). Obtained double-transgenic lines iSS4 and iSS5 dominantly expressed sorghum RbcS and accumulated 35% and 20% of Rubisco content of non-transgenic rice (WT), respectively. Rubisco in these double-transgenic lines showed higher kcat and Km for CO2 than WT and SS10. Moreover, iSS4 showed higher photosynthetic nitrogen use efficiency under high CO2 conditions. These results demonstrate the usefulness of C4-type RbcS to improve photosynthetic performance under elevated CO2 conditions