Canopy light gradient perception by cytokinin.
We have recently identified cytokinin as an important xylem-carried signal involved in the photosynthetic acclimation of plants to light gradients in dense canopies. Lower leaves become shaded in a dense canopy and consequently have reduced transpiration rates. our measurements have shown that this results in a reduced delivery of cytokinins carried in the transpiration stream to shaded leaves, as compared to light-exposed leaves. Cytokinins are involved in the regulation of photosynthetic acclimation to the light gradient by stimulating the expression of photosynthetic enzymes in light-exposed leaves. In shaded leaves, the low delivery rate of cytokinin leads to reduced photosynthetic capacity and ultimately senescence. We show evidence for this role of cytokinin, as part of a complex of signaling pathways where other regulatory mechanisms are also involved. A model is presented depicting the regulation of photosynthetic acclimation by cytokinin delivery to leaves dependent on the irradiance they receive.
Boonman
Alex
A
Plant Ecophysiology Group; Institute of Environmental Biology; Utrecht University; Utrecht, The Netherlands.
Pons
Thijs L
TL
Plant Mol Biol. 1988 Jul;11(4):409-15
24272397
Biochim Biophys Acta. 2000 Jun 21;1492(1):233-6
11004495
Trends Plant Sci. 1999 Mar;4(3):97-102
10322540
Plant Physiol. 2000 Dec;124(4):1706-17
11115887
Ann Bot. 2004 Nov;94(5):725-32
15374835
Science. 1995 Dec 22;270(5244):1986-8
8592746
Plant Cell Physiol. 2002 Sep;43(9):1059-66
12354925
Curr Opin Plant Biol. 1999 Jun;2(3):178-86
10375569
Plant Physiol. 1994 Feb;104(2):339-347
12232085
Ann Bot. 2005 Feb;95(3):507-19
15598701
Plant Cell Physiol. 2001 Jan;42(1):85-93
11158447
Am Nat. 2006 Nov;168(5):597-607
17080359
J Exp Bot. 2001 Jul;52(360):1563-74
11457917
Ann Bot. 2005 Feb;95(3):495-506
15585543
Ann Bot. 2005 Feb;95(3):483-94
15585544