Although resprouting plays an important role in facilitating persistence of damaged seedlings, the functional attributes of cotyledons and taproots during resprouting of 1-year oak seedlings are not well explored. In this study, cotyledons were removed from Quercus mongolica seedlings to explore resprouting in response to simulated disturbance as a function of shoot clipping, and to examine the...

Sucrose uptake was studied in isolated, immature pea cotyledons (Pisum sativum L. cv Marzia) in relation to their developmental stage. During the developmental period examined the water content of the cotyledons decreased from approximately 80% "stage 1" to approximately 55% "stage 2". When assayed in an isotonic medium (400 osmoles per cubic meter) the influx capacity per gram fresh weight for...

We investigated the effects of catecholamine on flower-induction in P. nil (cv. Violet). GC-SIM analysis identified dopamine for the first time in P. nil seedlings. Dopamine levels in the cotyledons did not show a significant change during the inducing dark treatment. The dopamine content of cotyledons exposed to various durations of darkness were 0.1-0.2 nmol/g fresh weight. The same content w...

The regulation of expression of the genes encoding the large subunit (LSU) and small subunit (SSU) of ribulose 1,5-bisphosphate carboxylase (RuBPCase) was examined in 1- through 8-day-old, dark-grown (etiolated) and light-grown amaranth cotyledons. RuBPCase specific activity in light-grown cotyledons increased during this 8-day period to a level 15-fold higher than in dark-grown cotyledons. Und...

Oilseed rape is characterized by a low nitrogen remobilization efficiency during leaf senescence, mainly due to a lack of proteolysis. Because cotyledons are subjected to senescence, it was hypothesized that contrasting protease activities between genotypes may be distinguishable early in the senescence of cotyledons. To verify this assumption, our goals were to (i) characterize protease activi...

Trehalose (a-D-glucosyl-[1,1]-a-D-glucopyranoside) is involved in mechanisms that coordinate metabolism with plant growth adaptation and development. The main objective of the current work was to find out whether trehalose feeding affects the expression of two genes involved in photosynthesis: one gene coding for photosystem1 subunit H (PS1-H) and the other for the light harvesting complex B1 (...

MicroRNAs (miRNAs) are an emerging class of small RNAs regulating a wide range of biological processes. Soybean cotyledons evolved as sink tissues to synthesize and store seed reserves which directly affect soybean seed yield and quality. However, little is known about miRNAs and their regulatory networks in soybean cotyledons. We sequenced 292 million small RNA reads expressed in soybean cotyl...

Arginine is the predominant free amino acid in the cotyledons of developing seeds of Pisum sativum L. cv Marzia. Breakdown of arginine was measured by injecting l-[guanido-(14)C]arginine into detached cotyledons. Cotyledons of developing seeds showed a low rate of (14)CO(2) evolution whereas a much higher rate of (14)CO(2) evolution was measured from cotyledons of seeds 4 days after the onset o...

A cDNA clone for isocitrate lyase (ICL) was isolated from a cDNA library prepared from the poly(A)+ RNA of etiolated pumpkin cotyledons. The cDNA encoded a polypeptide with 576 amino acids, whose sequence is more than 79% identical to those of ICL from other higher plants and contains the C-terminal tripeptide, Ser-Arg-Met, which is a putative targeting signal to microbodies. Immunogold analysi...

Previous work has shown the complement of leucyl transfer RNA (tRNA(Leu)) isoaccepting species present in soybean cotyledons to change during cotyledon senescence. Of the six tRNA(Leu) species resolved by Freon-column chromatography, the capacity of species 1-4 to accept leucine is decreased between 5 and 21 days of age. Parallel changes in tRNA(Leu) synthetase activity are reported here during...