Year: 2022

MASSIVE GENE CHANGES. "Continuing studies are likely to indicate that the conversion of a leaf from a photosynthetic system to a source of stored nutrients involves global changes in gene expression." https://lnkd.in/dNWP3KD View in LinkedIn

COMPLEXITY AND CONTROL. "The overall process of the senescence syndrome may be very complex, but it is still worth considering whether there are definable regulatory systems that have an overriding influence on the timing of the conversion from photosynthetic to salvage programs." https://lnkd.in/dNWP3KD View in LinkedIn

MASTER CONTROL. "Observations are consistent with the existence of master regulatory systems that can determine the timing of the senescence syndrome." https://lnkd.in/dNWP3KD View in LinkedIn

ABSCISSION. "During the course of development, plants shed entire organ systems through the process referred to as abscission. Abscission provides a mechanism for the removal of senescing or otherwise damaged organs and for the release of fruits as they ripen." https://lnkd.in/dNWP3KD View in LinkedIn

DISPOSABLE UNITS. "In some cases, intact, healthy organ systems may be shed as a component of development. The abscission of petals, sepals, and stamen as fruits begin to develop provides an example of this process." https://lnkd.in/dNWP3KD View in LinkedIn

SEVERANCE POINTS. "Abscission of organ systems occurs at anatomically distinct bands of cells referred to as abscission zones (AZs). AZs are often located in stems between the abscising organ and the body of the plant." https://lnkd.in/dNWP3KD View in LinkedIn

THE ACCELERATOR AND THE BRAKE. "Ethylene is the primary signal that drives the abscission process, whereas auxin reduces the sensitivity of AZ cells to ethylene and thus prevents or delays abscission. Subsequent studies in a variety of species support the idea that applied ethylene can stimulate abscission and that the inhibition of ethylene synthesis or action can delay abscission in many cases." (AZ = abscission zones). https://lnkd.in/dNWP3KD View in LinkedIn

ABSCISCIC ACID HORMONE (ABA). "Both the upregulation of genes associated with ABA signaling and a dramatic increase in endogenous ABA levels can be observed in many plants during leaf senescence." https://lnkd.in/dj6JXRP View in LinkedIn

SO ENDS a peek into the complexity of the control of leaf fall timing. This is influenced by numerous factors, both internal and external. It remains stunning, to me at least, that despite this complexity, trees march inexorably by species, one by one, exactly in synch, into the autumn leaf coloration and subsequent leaf drop. May your autumns be filled with wonder. View in LinkedIn

MULTICELLULARITY ROLE. "Our results indicate an origin of cyanobacteria before the rise of atmospheric oxygen. The evolution of multicellular forms coincides with the onset of the GOE and an increase in diversification rates. These results suggest that multicellularity could have played a key role in triggering cyanobacterial evolution around the GOE." (GOE = Great Oxygenation Event). http://www.pnas.org/content/110/5/1791.full View in LinkedIn