Contents of carbohydrates and endogenous hormones from dormancy to sprouting of Toona sinensis buds were measured. Dynamic changes of GA 1/3 , iPA and ABA were detected. GA 1/3 and iPA decreased when the dormancy bega...Contents of carbohydrates and endogenous hormones from dormancy to sprouting of Toona sinensis buds were measured. Dynamic changes of GA 1/3 , iPA and ABA were detected. GA 1/3 and iPA decreased when the dormancy began, and then increased to the highest value before bud sprouting. The lowest value of GA 1/3 , 358 7 ng·g -1 FW, was observed 21 days after leaf falling, whereas ABA was the highest, 201 5 ng g -1 FW. Thereafter, ABA decreased and GA 1/3 increased with the advent of bud sprouting. Ratios of GA/iPA and iPA/ABA decreased first and then increased from dormancy to sprouting with minor change range compared with GA 1/3 , iPA and ABA. This demonstrated that dormancy break was closely related to hormone change, concurrent with starch degradation and increase in soluble sugars.展开更多
Aims In this study,we examined the extent to which between-species leaf size variation relates to variation in the intensity of leaf production in herbaceous angiosperms.Leaf size variation has been most commonly inte...Aims In this study,we examined the extent to which between-species leaf size variation relates to variation in the intensity of leaf production in herbaceous angiosperms.Leaf size variation has been most commonly interpreted in terms of biomechanical constraints(e.g.affected by plant size limitations)or in terms of direct adaptation associated with leaf size effects in optimizing important physiological functions of individual leaves along environmental gradients(e.g.involving temperature and moisture).An additional interpretation is explored here,where adaptation may be more directly associated with the number of leaves produced and where relatively small leaf size then results as a trade-off of high‘leafing intensity’—i.e.number of leaves produced per unit plant body size.Methods The relationships between mean individual leaf mass,number of leaves and plant body size were examined for 127 species of herbaceous angiosperms collected from natural populations in southern Ontario,Canada.Important Findings In all,88%of the variation in mean individual leaf mass across species,spanning four orders of magnitude,is accounted for by a negative isometric(proportional)trade-off relationship with leafing intensity.These results parallel those reported in recent studies of woody species.Because each leaf is normally associated with an axillary bud or meristem,having a high leafing intensity is equivalent to having a greater number of meristems per unit body size—i.e.a larger‘bud bank’.According to the‘leafing intensity premium’hypothesis,because an axillary meristem represents the potential to produce either a new shoot or a reproductive structure,high leafing intensity should confer greater architectural and/or reproductive plasticity(with relatively small leaf size required as a trade-off).This greater plasticity,we suggest,should be especially important for smaller species since they are likely to suffer greater suppression of growth and reproduction from competition within multi-species vegetation.Accord展开更多
WUSCHEL （WUS） plays an essential role for the maintenance of meristem activity in dicots, but its function is still elusive in monocots. We isolated a new monoculm mutant, monoculm 3 （moc3）, in which a point mutat...WUSCHEL （WUS） plays an essential role for the maintenance of meristem activity in dicots, but its function is still elusive in monocots. We isolated a new monoculm mutant, monoculm 3 （moc3）, in which a point mutation causes the premature termination of rice O. sativa WUS （OsWUS）. Morphological observation revealed that the formation of tiller buds was disrupted in moc3. MOC3 was localized in the nuclear and could interact with TOPLESS-RELATED PROTEINS （TPRs）. The expression of MOC3 was induced by cytokinins and defection of MOC3 affected the expression of several two-component cytokinin response regulators, OsRRs and ORRs. Our results suggest that MOC3 is required for the formation of axillary buds and has a complex relationship with cytokinins.展开更多
文摘Contents of carbohydrates and endogenous hormones from dormancy to sprouting of Toona sinensis buds were measured. Dynamic changes of GA 1/3 , iPA and ABA were detected. GA 1/3 and iPA decreased when the dormancy began, and then increased to the highest value before bud sprouting. The lowest value of GA 1/3 , 358 7 ng·g -1 FW, was observed 21 days after leaf falling, whereas ABA was the highest, 201 5 ng g -1 FW. Thereafter, ABA decreased and GA 1/3 increased with the advent of bud sprouting. Ratios of GA/iPA and iPA/ABA decreased first and then increased from dormancy to sprouting with minor change range compared with GA 1/3 , iPA and ABA. This demonstrated that dormancy break was closely related to hormone change, concurrent with starch degradation and increase in soluble sugars.
基金Natural Sciences and Engineering Research Council of Canada Research Grant(14552 to L.W.A.),Undergraduate Student Research Award to T.W.
文摘Aims In this study,we examined the extent to which between-species leaf size variation relates to variation in the intensity of leaf production in herbaceous angiosperms.Leaf size variation has been most commonly interpreted in terms of biomechanical constraints(e.g.affected by plant size limitations)or in terms of direct adaptation associated with leaf size effects in optimizing important physiological functions of individual leaves along environmental gradients(e.g.involving temperature and moisture).An additional interpretation is explored here,where adaptation may be more directly associated with the number of leaves produced and where relatively small leaf size then results as a trade-off of high‘leafing intensity’—i.e.number of leaves produced per unit plant body size.Methods The relationships between mean individual leaf mass,number of leaves and plant body size were examined for 127 species of herbaceous angiosperms collected from natural populations in southern Ontario,Canada.Important Findings In all,88%of the variation in mean individual leaf mass across species,spanning four orders of magnitude,is accounted for by a negative isometric(proportional)trade-off relationship with leafing intensity.These results parallel those reported in recent studies of woody species.Because each leaf is normally associated with an axillary bud or meristem,having a high leafing intensity is equivalent to having a greater number of meristems per unit body size—i.e.a larger‘bud bank’.According to the‘leafing intensity premium’hypothesis,because an axillary meristem represents the potential to produce either a new shoot or a reproductive structure,high leafing intensity should confer greater architectural and/or reproductive plasticity(with relatively small leaf size required as a trade-off).This greater plasticity,we suggest,should be especially important for smaller species since they are likely to suffer greater suppression of growth and reproduction from competition within multi-species vegetation.Accord
基金supported by grants from the National Natural Science Foundation of China (No.91335204)the Ministry of Science and Technology (No.2013CBA01401)
文摘WUSCHEL （WUS） plays an essential role for the maintenance of meristem activity in dicots, but its function is still elusive in monocots. We isolated a new monoculm mutant, monoculm 3 （moc3）, in which a point mutation causes the premature termination of rice O. sativa WUS （OsWUS）. Morphological observation revealed that the formation of tiller buds was disrupted in moc3. MOC3 was localized in the nuclear and could interact with TOPLESS-RELATED PROTEINS （TPRs）. The expression of MOC3 was induced by cytokinins and defection of MOC3 affected the expression of several two-component cytokinin response regulators, OsRRs and ORRs. Our results suggest that MOC3 is required for the formation of axillary buds and has a complex relationship with cytokinins.
