Tagged: secondary growth


A diagram of the matter in question

Regulatory networks controlling the development of the root system and the formation of lateral roots

The production of a new lateral root from parental root primary tissues has been investigated extensively, and the most important regulatory mechanisms are now well known. A first regulatory mechanism is based on the synthesis of small peptides which interact ectopically with membrane receptors to elicit a modulation of transcription factor target genes. A second mechanism involves a complex cross-talk between plant hormones. It is known that lateral roots are formed even in parental root portions characterized by the presence of secondary tissues, but there is not yet agreement about the putative tissue source providing the cells competent to become...

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Example of a tree ring split into ten sectors (A) and representation of the anatomical features measured on each single tracheid (B).

Tree-ring anatomy reveals climatic influence on xylem morphogenesis

During the growing season, the cambium of conifer trees produces successive rows of xylem cells, known as tracheids. Current knowledge on this process mainly stems from xylogenesis monitoring spanning a few years. In this investigation of the effects of long-term inter-annual climate variability on tracheid formation and wall thickening, Castagneri et al. retrospectively study tree-ring xylem anatomy in Picea abies along an altitudinal gradient in the Alps. Climate fluctuations are shown to influence morphogenesis of tracheids sequentially formed in the growing season over successive periods. Morphogenetic mechanisms responsible for different tracheid traits are affected by climate to differing degrees according...

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