From the Flower Bud to the Mature Seed: Timing and Dynamics of Flower and Seed Development in High-Mountain Plants

2011 ◽  
pp. 135-152 ◽  
Author(s):  
Johanna Wagner ◽  
Ursula Ladinig ◽  
Gerlinde Steinacher ◽  
Ilse Larl
Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1507
Author(s):  
Johanna Wagner ◽  
Karla Gruber ◽  
Ursula Ladinig ◽  
Othmar Buchner ◽  
Gilbert Neuner

At higher elevations in the European Alps, plants may experience winter temperatures of −30 °C and lower at snow-free sites. Vegetative organs are usually sufficiently frost hardy to survive such low temperatures, but it is largely unknown if this also applies to generative structures. We investigated winter frost effects on flower buds in the cushion plants Saxifraga bryoides L. (subnival-nival) and Saxifraga moschata Wulfen (alpine-nival) growing at differently exposed sites, and the chionophilous cryptophyte Ranunculus glacialis L. (subnival-nival). Potted plants were subjected to short-time (ST) and long-time (LT) freezing between −10 and −30 °C in temperature-controlled freezers. Frost damage, ice nucleation and flowering frequency in summer were determined. Flower bud viability and flowering frequency decreased significantly with decreasing temperature and exposure time in both saxifrages. Already, −10 °C LT-freezing caused the first injuries. Below −20 °C, the mean losses were 47% (ST) and 75% (LT) in S. bryoides, and 19% (ST) and 38% (LT) in S. moschata. Winter buds of both saxifrages did not supercool, suggesting that damages were caused by freeze dehydration. R. glacialis remained largely undamaged down to −30 °C in the ST experiment, but did not survive permanent freezing below −20 °C. Winter snow cover is essential for the survival of flower buds and indirectly for reproductive fitness. This problem gains particular relevance in the context of winter periods with low precipitation and winter warming events leading to the melting of the protective snowpack.


Diversity ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 137
Author(s):  
Rosina Magaña Ugarte ◽  
María Pilar Gómez-Serranillos ◽  
Adrián Escudero ◽  
Rosario G. Gavilán

Albeit the remarkably high Ultraviolet B loads, high temperatures, and drought stress substantiate the need for efficient photoprotective strategies in Mediterranean high-mountain plants, these remain understudied. Considering the sensitivity of photosystems to extreme conditions, we evaluated an environmental gradient’s weight on the photoprotection of five high-mountain specialists from Central Spain. Diurnal and seasonal variations in chlorophyll, chlorophyll fluorescence, carotenoids, and xanthophylls in consecutive and climatically contrasting years were taken to evaluate the effect of the impending climate coarsening at the photosystem level. Our results revealed significant differences among species in the xanthophyll cycle functioning, acting either as a continuous photoprotective strategy enhancing photochemistry-steadiness; or prompted only to counteract the cumulative effects of atypically adverse conditions. The lutein cycle’s involvement is inferred from the high lutein content found in all species and elevations, acting as a sustained photoprotective strategy. These findings added to high de-epoxidation state (DEPS) and minor seasonal changes in the chlorophyll a/b ratio, infer the xanthophyll and Lutein cycles are crucial for upkeeping the photosystems’ optimal functioning in these plants heightening their photoprotective capacity during periods of more unfavorable conditions. Nevertheless, an atypically dry growing season’s detrimental effect infers the feasible surpassing of stress-thresholds and the precariousness of the communities’ functional diversity under climate change.


Author(s):  
Juan C. Mejía‐Giraldo ◽  
Cecilia Gallardo ◽  
Miguel A. Puertas‐Mejía

2017 ◽  
pp. 67
Author(s):  
Hilda Araceli Zavaleta-Mancera

The seed of the Mexican species, Casimiroa edulis Llave et Lexarza is valued for medicinal purposes. We have studied its anatomy in different stages of development from ovule to mature seed. We applied general staining with safranin and fast green and specific staining for the detection of starch, lipids, lignin, polyphenols, and proteins. Embryo and seed development was also evaluated on the basis of volume. The ovule is sessile, bitegmic, crassinucellate, hemianatropous, with a nucellar curvature of 30-40º and a large hilum. The seed develops a large pachychalaza that covers approximately 70% of the surface. The testa is thin, nonlignified and tanniferous. The mature embryo occupies about 90% of the whole volume of the seed and contains lysigenous oil glands, starch grains and protein bodies. The radicle is not directed exactly at the micropyle. lt is located in the dorsal micropylar third of the seed. Casimiroa edulis had been described as lacking endosperm, but in reality the mature seed has a small amount of endosperm under the pachychalaza.


Planta ◽  
1998 ◽  
Vol 207 (2) ◽  
pp. 313-324 ◽  
Author(s):  
P. Streb ◽  
W. Shang ◽  
J. Feierabend ◽  
R. Bligny

2009 ◽  
Vol 18 (1) ◽  
pp. 78-87 ◽  
Author(s):  
Conny Thiel-Egenter ◽  
Felix Gugerli ◽  
Nadir Alvarez ◽  
Sabine Brodbeck ◽  
Elżbieta Cieślak ◽  
...  

2007 ◽  
Vol 55 (4) ◽  
pp. 450 ◽  
Author(s):  
Susanna E. Venn ◽  
John W. Morgan

Alpine snowpatch vegetation in Australia is restricted to high mountain areas and occurs in locations where winter snow persists longest into the summer. The timing of annual snowmelt is considered an important determinant of vegetation patterns in alpine areas because it affects the length of the growing season for plant species at landscape scales. There are few studies in Australia that have examined the effects of the date of snowmelt on the performance of plant species at small spatial scales. The phytomass and phenology of three common snowpatch species (Celmisia pugioniformis, Luzula acutifolia, Poa fawcettiae) was examined during one growing season across a natural snowmelt gradient to examine their response to time of snow release. Peak phytomass was significantly higher in early than late-melting zones for L. acutifolia and marginally higher there for C. pugioniformis. P. fawcettiae, however, produced higher mean peak phytomass in late-melting zones where soil was initially wetter in the growing season. Flower buds of L. acutifolia were evident as the snow melted, and flowering occurred at the same time in all areas of the snowpatch. The number of days from the date of snowmelt to the date of the first observed flower bud in C. pugioniformis and P. fawcettiae was 22–25 days shorter in late-melting areas than in early melting areas. For both of these species, flowering and subsequent seed set occurred simultaneously across the snowpatch regardless of the date of the initial snowmelt, suggesting that photoperiod controls flowering in these species. Our study suggests that the predicted declines in snow cover in Australia in coming decades may affect the phytomass of species that are currently constrained by late-lying snow. This, in turn, may affect their long-term patterns of distribution. If plants respond to photoperiod for flowering, as seems to be important here for C. pugioniformis and P. fawcettiae, it is unlikely that the periods following earlier than usual snowmelt will be fully utilised by these species. Any attempts at predicting or modelling future alpine plant distribution on the basis of warming scenarios may therefore need to account for photoperiod constraints on flowering as well changes in phytomass production.


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