Cambial activity is a prerequisite for secondary growth in plants; however, regulatory factors controlling the activity of the secondary meristem in radial growth remain elusive. Here, we identified INCREASED CAMBIAL ...Cambial activity is a prerequisite for secondary growth in plants; however, regulatory factors controlling the activity of the secondary meristem in radial growth remain elusive. Here, we identified INCREASED CAMBIAL ACTIVITY （ICA）, a gene encoding a putative pectin methyltransferase, which could function as a modulator for the meristematic activity of fascicular and interfascicular cambium in Arabidopsis. An overexpressing transgenic line, 35S：＇1CA, showed accelerated stern elongation and radial thickening, resulting in increased accumulation of biomass, and increased levels of cytokinins （CKs） and gibberellins （GAs）. Expression of genes encoding pectin methylesterases involved in pectin modification together with pectin methyltransferases was highly induced in 355：：ICA, which might contribute to an increase of methanol emission as a byproduct in 35S：ICA. Methanol treatment induced the expression of GA- or CK-responsive genes and stimulated plant growth. Overall, we propose that ectopic expression of ICA increases cambial activity by regulating CK and GA homeostasis, and methanol emission, eventually leading to stem elongation and radial growth in the inflorescence stem.展开更多
Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesize...Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.展开更多
基金the support of “Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ010953022016)” Rural Development Administration, Korea
文摘Cambial activity is a prerequisite for secondary growth in plants; however, regulatory factors controlling the activity of the secondary meristem in radial growth remain elusive. Here, we identified INCREASED CAMBIAL ACTIVITY （ICA）, a gene encoding a putative pectin methyltransferase, which could function as a modulator for the meristematic activity of fascicular and interfascicular cambium in Arabidopsis. An overexpressing transgenic line, 35S：＇1CA, showed accelerated stern elongation and radial thickening, resulting in increased accumulation of biomass, and increased levels of cytokinins （CKs） and gibberellins （GAs）. Expression of genes encoding pectin methylesterases involved in pectin modification together with pectin methyltransferases was highly induced in 355：：ICA, which might contribute to an increase of methanol emission as a byproduct in 35S：ICA. Methanol treatment induced the expression of GA- or CK-responsive genes and stimulated plant growth. Overall, we propose that ectopic expression of ICA increases cambial activity by regulating CK and GA homeostasis, and methanol emission, eventually leading to stem elongation and radial growth in the inflorescence stem.
基金supported by the National Natural Science Foundations of China(41525001,41661144040,41601204)supported by the Bilateral Project between China and Slovenia(BI-CN/09–11-012)+1 种基金COST Action(FP1106,STRe ESS)supported by the Chinese Academy of Sciences President International Fellowship Initiative for Visiting Scientists(2016VBA074)
文摘Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.
