Growth and Development in Microculture of Gametophytes From Stored Spores of Equisetum

The chlorophyllous spores of Equisetum survive desiccation, yet cannot tolerate this quiescent state for more than ~2 wk. The hypothesis that spore viability of Equisetum hyemale L. is limited by inhibition of photosynthetic recovery was tested using chlorophyll a fluorescence and oxygen-exchange analyses. Experimental spores were desiccated at 2% relative humidity and 25C for time periods of 24 h, 1 wk, and 2 wk, and then rehydrated at 200 mmol photons/m2s (PAR) and 25C for up to 24 h. Spores desiccated for 24 h recovered photosynthetic competence very rapidly during rehydration, reaching the O2 compensation point in 6.3 ~ 0.3 (mean +/- SE) min. Recovery of photosynthetic performance of spores desiccated for 1 wk was slower, as judged by significantly slower increases of (1) photochemical efficiency of photosystem (PS) II, (2) PS II quinoneB-reducing center concentration, (3) quinoneB concentration, (4) water-oxidation activity, (5) rate of light-induced O2 evolution, and (6) apparent quantum yield of net O2 exchange. Photosystem-II and whole-spore photosynthetic competence of 2-wk desiccated spores was increasingly impaired, and did not recover during rehydration. Origin fluorescence yield and dark respiration were not affected by desiccation time following rehydration. The results suggest that the extremely short viability of disseminated spores of Equisetum hyemale is due to the inability to recover losses of water oxidation and photosystem II-core function following 2 wk of desiccation.

Section: Relative Water Content and Germination-mentioning

confidence: 99%

Section: Relative Water Content and Germination-mentioning

confidence: 99%

Desiccation‐time limits of photosynthetic recovery in Equisetum hyemale (Equisetaceae) spores

Lebkuecher

1997

“…Male gametophytes, regenerated with progynon, remained only male. More recently several authors (Castle, 1953;Wollersheim, 1957a, b;LaRoche, 1967;Jones and Hook, 1970) have cultured Equisetum gametophytes under various conditions, but none have related their results to sexual determination in this genus.…”

mentioning

confidence: 99%

The Effect of Light Quality and Intensity on Sexual Expression in Equisetum Gametophytes

Hauke¹

1971

A series of experiments to determine the effect of light quality and light intensity on sexual expression in Equisetum gametophytes showed that one species, E. arvense, is strongly affected by light intensity; another species, E. hyemale, is strongly affected by light quality; and a third species, E. fluviatile, is relatively unaffected by either light quality or light intensity. Supplementation of mineral media with sucrose indicates that this light effect is not photosynthetic, and in fact suggests that sucrose itself has a morphogenetic effect on sexual determination in Equisetum gametophytes.

The Release Mechanism and Locomotor Behavior of Equisetum Sperm

Bilderback

Jahn

Fonseca

1973

When antheridia of gametophytes of Equisetum hyemale L. are placed in water, only spermatid cells are released. These spermatid cells have from 6–12 fibrils radiating from 2–4 loci on the cell wall. One sperm is released from each spermatid cell. With high speed cinemicrography, it can be shown that sperm flagella beat three dimensionally with a continuous, traveling helical wave. A flagellar beat cycle is completed every 0.03 sec. In water the sperm swim rapidly at a rate of 300 μ per sec and traverse a helical path of long wavelength and shallow amplitude. Calcium is essential for normal locomotor behavior. When calcium is chelated by ethylenediaminetetraacetate (EDTA), the sperm spin in place. All other monovalent and divalent ionic solutions tested cause the sperm to swim abnormally. Monovalent ionic solutions prevent the drastic change in sperm mobility patterns resulting from chelation by EDTA.