Time filter

Source Type

Ookawa T.,Tokyo University of Agriculture and Technology | Hobo T.,Nagoya University | Yano M.,Japan National Institute of Agrobiological Science | Murata K.,Agricultural Research Institute | And 11 more authors.
Nature Communications

The use of fertilizer results in tall rice plants that are susceptible to lodging and results in reduced plant yields. In this study, using chromosome segment substitution lines, we identified an effective quantitative trait loci (QTL) for culm strength, which was designated STRONG CULM2 (SCM2). Positional cloning of the gene revealed that SCM2 was identical to ABERRANT PANICLE ORGANIZATION1 (APO1), a gene previously reported to control panicle structure. A near-isogenic line carrying SCM2 showed enhanced culm strength and increased spikelet number because of the pleiotropic effects of the gene. Although SCM2 is a gain-of-function mutant of APO1, it does not have the negative effects reported for APO1 overexpression mutants, such as decreased panicle number and abnormal spikelet morphology. The identification of lodging-resistance genes by QTL analysis combined with positional cloning is a useful approach for improving lodging resistance and overall productivity in rice. © 2010 Macmillan Publishers Limited. All rights reserved. Source

Kikuchi R.,Japan National Institute of Agrobiological Science | Kikuchi R.,Yokohama City University | Kawahigashi H.,Japan National Institute of Agrobiological Science | Oshima M.,University of Tsukuba | And 4 more authors.
Journal of Experimental Botany

HvCO9 was characterized to elucidate the barley flowering control mechanisms and to investigate the functional diversification of the barley CONSTANS-like (CO-like) genes in flowering. HvCO9 was located on the same chromosome, 1HL, as Ppd-H2 (HvFT3), which is a positive regulator of short-day (SD) flowering. A phylogenetic analysis showed that HvCO9 was located on the same branch of the CO-like gene tree as rice Ghd7 and the barley and wheat VRN2 genes, which are all negative regulators of flowering. High level HvCO9 expressions were observed under SD conditions, whereas its expression levels were quite low under long-day (LD) conditions. HvCO9 expression correlated with HvFT1 and HvFT2 expression under SD conditions, although no clear effect of HvCO9 on HvFT3 expression, or vice versa, under SD conditions was observed. The over-expression of HvCO9 in rice plants produced a remarkable delay in flowering. In transgenic rice, the expression levels of the flowering-related Ehd1 gene, which is a target gene of Ghd7, and its downstream genes were suppressed, causing a delay in flowering. These results suggest that HvCO9 may act as a negative regulator of flowering under non-inductive SD conditions in barley; this activity is similar to that of rice Ghd7 under non-inductive LD conditions, but the functional targets of these genes may be different. Our results indicate that barley has developed its own pathways to control flowering by using homologous genes with modifications for the timing of expression. Further, it is hypothesized that each pathway may target different genes after gene duplication or species diversification. © 2011 The Author. Source

Itoh H.,Japan National Institute of Agrobiological Science | Nonoue Y.,Institute of the Society for Techno innovation of Agriculture | Yano M.,Japan National Institute of Agrobiological Science | Izawa T.,Japan National Institute of Agrobiological Science
Nature Genetics

The critical day length triggering photoperiodic flowering is set as an acute, accurate threshold in many short-day plants, including rice 1,2. Here, we show that, unlike the Arabidopsis florigen gene FT 3, the rice florigen gene Hd3a (Heading date 3a) is toggled by only a 30-min day-length reduction. Hd3a expression is induced by Ehd1 (Early heading date 1) expression when blue light coincides with the morning phase set by OsGIGANTEA(OsGI)-dependent circadian clocks. Ehd1 expression is repressed by both night breaks under short-day conditions and morning light signals under long-day conditions. Ghd7 (Grain number, plant height and heading date 7) was acutely induced when phytochrome signals coincided with a photosensitive phase set differently by distinct photoperiods and this induction repressed Ehd1 the next morning. Thus, two distinct gating mechanismsof the floral promoter Ehd1 and the floral repressor Ghd7could enable manipulation of slight differences in day length to control Hd3a transcription with a critical day-length threshold. © 2010 Nature America, Inc. All rights reserved. Source

Ogiso E.,University of Tsukuba | Takahashi Y.,Institute of the Society for Techno innovation of Agriculture | Takahashi Y.,Nagoya University | Sasaki T.,Japan National Institute of Agrobiological Science | And 4 more authors.
Plant Physiology

Casein kinase II (CK2) is a protein kinase with an evolutionarily conserved function as a circadian clock component in several organisms, including the long-day plant Arabidopsis (Arabidopsis thaliana). The circadian clock component CIRCADIAN CLOCK ASSOCIATED1 (CCA1) is a CK2 target in Arabidopsis, where it influences photoperiodic flowering. In rice (Oryza sativa), a shortday plant, Heading date6 (Hd6) encodes a CK2α subunit that delays flowering time under long-day conditions. Here, we demonstrate that control of flowering time in rice by the Hd6 CK2a subunit requires a functional Hd1 gene (an Arabidopsis CONSTANS ortholog) and is independent of the circadian clock mechanism. Our findings from overexpressing the dominantnegative CK2 allele in rice support the independence of CK2 function from the circadian clock. This lack of control of the circadian clock by Hd6 CK2α might be due to the presence of glutamate in OsLHY (a CCA1 ortholog in rice) instead of the serine at the corresponding CK2 target site in CCA1. However, this glutamate is critical for the control of the OsPRR1 gene (a rice ortholog of the Arabidopsis TOC1/PRR1 gene) by OsLHY for regulation of the circadian clock. We also demonstrated that the other conserved CK2 target sites in OsLHY conferred robust rhythmic expression of OsLHY-LUC under diurnal conditions. These findings imply that the role of CK2 in flowering-time regulation in higher plants has diversified during evolution. © 2009 American Society of Plant Biologists. Source

Ohsumi A.,Japan National Agricultural Research Center | Takai T.,Japan National Agriculture and Food Research Organization | Ida M.,Kumiai Chemical Industry Co. | Yamamoto T.,Japan National Institute of Agrobiological Science | And 4 more authors.
Field Crops Research

Rice yield potential is determined by the balance between sink size and source capacity. To clarify the factors that limit yield in temperate japonica cultivars, we compared the yield performance of Sasanishiki, a temperate japonica cultivar, with those of three near-isogenic lines (NILs) of Sasanishiki with introgression of quantitative trait loci (QTL) derived from a high-yielding indica cultivar, Habataki: qSBN1, which increases the number of secondary rachis branches; qPBN6, which increases the number of primary rachis branches; and a pyramid line that combines these two QTLs. NIL (SBN1), NIL (PBN6), and NIL (SBN1+. PBN6) produced 28-37%, 9-16%, and 62-65% more spikelets per panicle than Sasanishiki, respectively. However, the NILs with increased spikelet number per panicle did not increase grain yield significantly, because compensation is taken place among different yield components. The pyramid line nevertheless had 4-12% higher yield than Sasanishiki due to greater translocation of carbohydrates from stem to panicle. There was no difference in carbohydrate accumulation before heading or in biomass production among Sasanishiki and the three NILs. The results indicate that increasing sink size does not substantially improve yield in Sasanishiki, which lacks sufficient substrate supply to fully satisfy the increased sink demand that results from the spikelet-number QTLs. © 2010 Elsevier B.V. Source

Discover hidden collaborations