The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased s...The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essentialfunctions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.展开更多
Secondary growth and wood formation are products of the vascular cambium, a lateral meristem. Although the mechanisms have only recently begun to be uncovered, transcriptional regulation appears increasingly central t...Secondary growth and wood formation are products of the vascular cambium, a lateral meristem. Although the mechanisms have only recently begun to be uncovered, transcriptional regulation appears increasingly central to the regulation of secondary growth. The importance of transcriptional regulation is illustrated by the correlation of expression of specific classes of genes with related biological processes occurring at specific stages of secondary growth, including cell division, cell expansion, and cell differentiation. At the same time, transcription factors have been characterized that affect specific aspects of secondary growth, including regulation of the cambium and differentiation of cambial daughter cells. In the present review, we summarize evidence pointing to transcription as a major mechanism for regulation of secondary growth, and outline future approaches for comprehensively describing transcriptional networks underlying secondary growth.展开更多
While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast ...While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an amphivasal organization of tracheids encircling a central strand of phloem. Currently there is no information concerning the molecular genetic basis of the develop- ment or evolution of the monocot cambium. Here we report high-quality transcriptomes for monocot cambium and early derivative tissues in two monocot genera, Yucca and Cordyline. Monocot cambium transcript profiles were compared to those of vascular cambia and secondary xylem tissues of two forest tree species, Populus trichocarpa and Eucalyptus grandis. Monocot cambium transcript levels showed that there are extensive overlaps between the regulation of monocot cambia and vascular cambia. Candidate regulatory genes that vary between the monocot and vascular cambia were also identified, and included members of the KANADI and CLE families involved in polarity and cell-cell signaling, respectively. We suggest that the monocot cambium may have evolved in part through reactivation of genetic mechanisms involved in vascular cambium regulation.展开更多
Plants modify development in response to external stimuli, to produce new growth that is appropriate for environmental conditions. For example, gravistimulation of leaning branches in angiosperm trees results in modif...Plants modify development in response to external stimuli, to produce new growth that is appropriate for environmental conditions. For example, gravistimulation of leaning branches in angiosperm trees results in modifications of wood development, to produce tension wood that pulls leaning stems upright. Here, we use gravistimulation and tension wood response to dissect the temporal changes in gene expression underlying wood formation in Populus stems. Using time-series analysis of seven time points over a 14-d experiment, we identified 8,919 genes that were differentially expressed between tension wood (upper) and opposite wood (lower) sides of leaning stems. Clustering of differentially expressed genes showed four major transcriptional responses, including gene clusters whose transcript levels were associated withtwo types of tissue-specific impulse responses that peaked at about 24-48h, and gene clusters with sustained changes in transcript levels that persisted until the end of the 14-d experiment. Functional enrichment analysis of those clusters suggests they reflect temporal changes in pathways associated with hormone regulation, protein Iocalization, cell wall biosynthesis and epigenetic pro- cesses. Time-series analysis of gene expression is an underutilized approach for dissecting complex develop- mental responses in plants, and can reveal gene clusters and mechanisms influencing development.展开更多
基金supported in part by the National Science Foundation (grants IOS-0752997 and IOS-0918433 to WJL grants IOS#0749731, IOS#051909 to PK)+8 种基金the Department of Energy, Division of Energy Biosciences (grantsDE-FG02-94ER20134 to WJL)the US Department of Agriculture, Agricultural Research Service (under Agreement number58-6250-0-008 to MAG)the Spanish Ministry of Science andInnovation (MICINN) (grants AGL2007-61948 and AGL2009-09018 to AFLM)the Ministry of Education, Science, Sportsand Culture of Japan (grant 19060009 to HF)the JapanSociety for the Promotion of Science (JSPS grant 23227001to HF)the NC-CARP project (to HF)the NationalKey Basic Research Program of China (grant 2012CB114500to XH)the National Natural Science Foundation of China (grant31070156 to XH)the NSFC-JSPS cooperation project(grant 31011140070 to HF and XH)
文摘The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essentialfunctions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.
基金Supported by USDA NRI Grant 2006-03387Department of Energy grant DE-A102-05ER64115
文摘Secondary growth and wood formation are products of the vascular cambium, a lateral meristem. Although the mechanisms have only recently begun to be uncovered, transcriptional regulation appears increasingly central to the regulation of secondary growth. The importance of transcriptional regulation is illustrated by the correlation of expression of specific classes of genes with related biological processes occurring at specific stages of secondary growth, including cell division, cell expansion, and cell differentiation. At the same time, transcription factors have been characterized that affect specific aspects of secondary growth, including regulation of the cambium and differentiation of cambial daughter cells. In the present review, we summarize evidence pointing to transcription as a major mechanism for regulation of secondary growth, and outline future approaches for comprehensively describing transcriptional networks underlying secondary growth.
基金the US Forest ServiceUSDA AFRI grants 2011-67013-30062 and 2014-04041supported by NSF PGRP Fellowship grant IOS-1402064
文摘While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an amphivasal organization of tracheids encircling a central strand of phloem. Currently there is no information concerning the molecular genetic basis of the develop- ment or evolution of the monocot cambium. Here we report high-quality transcriptomes for monocot cambium and early derivative tissues in two monocot genera, Yucca and Cordyline. Monocot cambium transcript profiles were compared to those of vascular cambia and secondary xylem tissues of two forest tree species, Populus trichocarpa and Eucalyptus grandis. Monocot cambium transcript levels showed that there are extensive overlaps between the regulation of monocot cambia and vascular cambia. Candidate regulatory genes that vary between the monocot and vascular cambia were also identified, and included members of the KANADI and CLE families involved in polarity and cell-cell signaling, respectively. We suggest that the monocot cambium may have evolved in part through reactivation of genetic mechanisms involved in vascular cambium regulation.
基金supported by grant 2015-67013-22891 USDA AFRI to A.G. and V.F.supported by NSF PGRP Fellowship grant IOS-1402064supported by NIH S10 Instrumentation Grants S10RR029668 and S10RR027303
文摘Plants modify development in response to external stimuli, to produce new growth that is appropriate for environmental conditions. For example, gravistimulation of leaning branches in angiosperm trees results in modifications of wood development, to produce tension wood that pulls leaning stems upright. Here, we use gravistimulation and tension wood response to dissect the temporal changes in gene expression underlying wood formation in Populus stems. Using time-series analysis of seven time points over a 14-d experiment, we identified 8,919 genes that were differentially expressed between tension wood (upper) and opposite wood (lower) sides of leaning stems. Clustering of differentially expressed genes showed four major transcriptional responses, including gene clusters whose transcript levels were associated withtwo types of tissue-specific impulse responses that peaked at about 24-48h, and gene clusters with sustained changes in transcript levels that persisted until the end of the 14-d experiment. Functional enrichment analysis of those clusters suggests they reflect temporal changes in pathways associated with hormone regulation, protein Iocalization, cell wall biosynthesis and epigenetic pro- cesses. Time-series analysis of gene expression is an underutilized approach for dissecting complex develop- mental responses in plants, and can reveal gene clusters and mechanisms influencing development.