Long-term Respiratory Cost of Maintenance and Growth of Field-grown Young Hinoki Cypress (Chamaecyparis obtusa)

Respiration rate of the entire above-ground parts of field-grown8-year-old hinoki cypress [Chamaecyparis obtusa(Sieb. et Zucc.)Endl.] was measured at monthly intervals over a 5-year period,to evaluate the trend in proportion of maintenance and growthcomponents of respiration with stand development. Representativesample trees were selected for respiration measurements. Theannual respiration rates of individual sample trees were combinedand partitioned into maintenance and growth components by regressingspecific respiration rate on mean relative growth rate. Maintenanceand growth respiration coefficients generated in this way were5.2 mol CO₂kg^-1year^-1and 39 mol  CO₂kg^-1, which are equivalentto 14.3 mg C kg^-1C h^-1(at mean annual air temperature of 15.1°C) and 0.94 kg C kg^-1C. Considering the maintenance andgrowth respiration coefficients, and phytomass and phytomassincrement of individual trees in the stand, the maintenanceand growth respiration rates of the stand were estimated. Theproportion of the maintenance respiration increased, whereasthat of the growth respiration decreased with stand development,due to decreasing relative growth rate.Copyright 1997 Annalsof Botany Company Chamaecyparis obtusa; growth respiration coefficient; hinoki; maintenance respiration coefficient; stand respiration     

Molecular cloning and characterization of the AVR-Pia locus from a Japanese field isolate of Magnaporthe oryzae

In order to clone and analyse the avirulence gene AVR-Pia from Japanese field isolates of Magnaporthe oryzae , a mutant of the M. oryzae strain Ina168 was isolated. This mutant, which was named Ina168m95-1, gained virulence towards the rice cultivar Aichi-asahi, which contains the resistance gene Pia. A DNA fragment (named PM01) that was deleted in the mutant and that co-segregated with avirulence towards Aichi-asahi was isolated. Three cosmid clones that included the regions that flanked PM01 were isolated from a genomic DNA library. One of these clones (46F3) complemented the mutant phenotype, which indicated clearly that this clone contained the avirulence gene AVR-Pia . Clone 46F3 contained insertions of transposable elements. The 46F3 insert was divided into fragments I–VI, and these were cloned individually into a hygromycin-resistant vector for the transformation of the mutant Ina168m95-1. An inoculation assay of the transformants revealed that fragment V (3.5 kb) contained AVR-Pia . By deletion analysis of fragment V, AVR-Pia was localized to an 1199-bp DNA fragment, which included a 255-bp open reading frame with weak homology to a bacterial cytochrome- c -like protein. Restriction fragment length polymorphism analysis of this region revealed that this DNA sequence co-segregated with the AVR-Pia locus in a genetic map that was constructed using Chinese isolates.