UMass Amherst lignin research sheds light on how plants adapt to environmental stress

In Massachusetts, new research may advance our understanding of “how the relative proportions of biopolymers,” like lignin, “are controlled in plant tissue”. The study, led by Sam Hazen at the University of Massachusetts Amherst, was published in Nature on December 24th, and should assist future research that may allow manipulation of the xylem regulatory network in plants and engineer energy crops for biofuel production.

Hazen, Brady and colleagues explored how a large number of interconnected transcription factors regulate xylem and cell wall thickening. Specifically, using a systems approach to identify protein-DNA interactions, they screened more than 460 transcription factors expressed in root xylem to explore their ability to bind the promoters of about 50 genes known to be involved in processes that produce cell-wall components. Hazen says, “This revealed a highly interconnected network of more than 240 genes and more than 600 protein-DNA interactions that we had not known about before.” They also found that each cell-wall gene in the xylem regulatory network is bound by an average of five different transcription factors from 35 distinct families of regulatory proteins. Further, many of the transcription factors form a surprisingly large number of feed-forward loops that co-regulate target genes.

In other words, rather than a series of on-off switches that leads to an ultimate action like making cellulose, most of the proteins including regulators of cell cycle and differentiation bind directly to cellulose genes and to other transcription regulators. This gives plants a huge number of possible combinations for responding and adapting to environmental stress such as salt or drought, the authors point out in Nature.

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