Genetic analysis of the rice jasmonate receptors reveals specialized functions for OsCOI2.

COI1-mediated perception of jasmonate is critical for plant development and responses to environmental stresses. Monocots such as rice have two groups of COI genes due to gene duplication: OsCOI1a and OsCOI1b that are functionally equivalent to the dicotyledons COI1 and OsCOI2 whose function remains unclear. In order to assess the function of OsCOI2 and its functional redundancy with COI1 genes, we developed a series of rice mutants in the 3 genes OsCOI1a, OsCOI1b and OsCOI2 by CRISPR Cas9-mediated editing and characterized their phenotype and responses to jasmonate. Characterization of OsCOI2 uncovered its important roles in root, leaf and flower development. In particular, we show that crown root growth inhibition by jasmonate relies on OsCOI2 and not on OsCOI1a nor on OsCOI1b, revealing a major function for the non-canonical OsCOI2 in jasmonate-dependent control of rice root growth. Collectively, these results point to a specialized function of OsCOI2 in the regulation of plant development in rice and indicate that sub-functionalisation of jasmonate receptors has occurred in the monocot phylum.

Functional Diversification of euANT/PLT Genes in Oryza sativa Panicle Architecture Determination.

Grain yield, which is one of the most important traits in rice breeding, is controlled in part by panicle branching patterns. Numerous genes involved in the control of panicle architecture have been identified through mutant and QTL characterization. Previous studies suggested the importance of several AP2/ERF transcription factor-encoding genes in the control of panicle development, including the AINTEGUMENTA/PLETHORA-like (euANT/PLT) genes. The ANT gene was specifically considered to be a key regulator of shoot and floral development in Arabidopsis thaliana. However, the likely importance of paralogous euANT/PLT genes in the regulation of meristem identities and activities during panicle architecture development has not to date been fully addressed in rice. In this study, we observed that the rice euANT/PLT genes displayed divergent temporal expression patterns during the branching stages of early panicle development, with spatial localization of expression in meristems for two of these genes. Moreover, a functional analysis of rice ANT-related genes using genome editing revealed their importance in the control of panicle architecture, through the regulation of axillary meristem (AM) establishment and meristem fate transition. Our study suggests that the paralogous euANT/PLT genes have become partially diversified in their functions, with certain opposing effects, since they arose from ancestral gene duplication events, and that they act in regulating the branching of the rice panicle.

Association between neighborhood active living potential and walking.

This paper examines the association between neighborhood active living potential and walking among middle-aged and older adults. A sample of 2,614 (61.1% women) persons aged 45 years or older and living in one of 112 census tracts in Montreal, Canada, were recruited between February and May of 2005 to participate in a 20-minute telephone survey. Data were linked to observational data on neighborhood active living potential in the 112 census tracts and analyzed through multilevel modeling. Greater density of destinations in the census tract was associated with greater likelihoods of walking for any reason at least 5 days per week for at least 30 minutes (odds ratio = 1.53, 95% confidence interval: 1.21, 1.94). Associations were attenuated but remained statistically significant after controlling for socioeconomic, health, lifestyle, and other physical activity characteristics. Sensitivity analyses showed that associations were robust across smaller and larger volumes of walking. No associations were found between dimensions of neighborhood active living potential and walking for recreational reasons. The authors conclude that a larger number and variety of neighborhood destinations in one's residential environment are associated with more walking and possibly more utilitarian walking among middle-aged or older adults.

From walkability to active living potential: an "ecometric" validation study.

BACKGROUND: The purpose of this paper is to establish the reliability and validity of a neighborhood-level measure of active living potential by applying principles of ecometrics. METHODS: Following a 3-day training session, observers (n =8) were provided with a map of a predetermined walking route constructed through the joining of ten randomly selected street blocks. Then, using an 18-item observation grid, pairs of observers performed ratings of 112 neighborhoods. Resulting observations produced a hierarchically structured data set including 4032 observations nested within observers, which in turn were nested within neighborhoods. Data from the 2001 Canadian census were linked to the neighborhood data. RESULTS: Application of ecometric multilevel modeling analyses showed that once interitem and interobserver variability were statistically controlled, about one third of the variability in observations were at the between-neighborhood level. Reliability estimates were 0.78 for items measuring activity-friendliness, 0.76 for safety, and 0.83 for density of destinations. Assessment of the convergent validity of the instrument identified that safety of the environment was positively associated with neighborhood affluence. Density of destinations was negatively associated with affluence and positively associated with higher proportions of persons in the neighborhood walking to work. CONCLUSIONS: The three dimensions of the neighborhood active-living potential measure have good reliability and convergent validity and are able to capture between neighborhood differences. Measurement characteristics would have been difficult to ascertain without the ecometrics methodology.