5-Aminolevulinic Acid Ameliorates the Growth, Photosynthetic Gas Exchange Capacity, and Ultrastructural Changes Under Cadmium Stress in Brassica napus L.

The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.

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Gas exchange and its factorial dependency in field-grown Brassica napus L.

European Journal of Agronomy ◽

10.1016/s1161-0301(98)00029-x ◽

1998 ◽

Vol 9 (1) ◽

pp. 53-70 ◽

Cited By ~ 14

Author(s):

C.R Jensen ◽

V.O Mogensen ◽

M.N Andersen ◽

I.E Henson

Keyword(s):

Brassica Napus ◽

Gas Exchange ◽

Brassica Napus L

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Activation of rape (Brassica napus L.) embryo during seed germination. V. The first zones of ultrastructural changes and their expansion

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1987.009 ◽

2014 ◽

Vol 56 (1) ◽

pp. 77-91 ◽

Cited By ~ 5

Author(s):

Mieczysław Karaś

Keyword(s):

Brassica Napus ◽

Seed Germination ◽

Seed Coat ◽

Basal Part ◽

Ultrastructural Changes ◽

Embryo Axis ◽

Brassica Napus L ◽

Root Cells ◽

Basal Zone

In the germinating rape embryo the columella and basal part of hypocotyl undergo earliest activation. Its first ultrastructural symptom is the appearance of numerous ER vesicles after 3-6 h of seed swelling. Their number is the highest in the external layers of the columella and decreases in basipetal direction. Dermatogen cells in the basal zone of the hypocotyl contain the greatest amount of ER structures, whereas decreasing amounts are found in both directions along the embryo axis and centripetally. Further changes in the ER spread in a similar order. The vesicles merge and form a tubular and plate-like ER. Then, they disappear and are replaced by tubular and vesicular forms. The changes in the ER are gradually followed by ultrastructural symptoms of activation of mitochondria, plastids and dictyosomes. The highest number of ER structures and other organelles accumulate in root cells shortly before piercing of the seed coat. After germination their amount decreases and remains almost stable.

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