کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6388861 1628071 2014 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ice barriers promote supercooling and prevent frost injury in reproductive buds, flowers and fruits of alpine dwarf shrubs throughout the summer
ترجمه فارسی عنوان
موانع یخ باعث افزایش خستگی و جلوگیری از آسیب یخ زده در جوانه های تولید مثل، گل ها و میوه های درختچه کوتوله کوهی در سراسر تابستان
کلمات کلیدی
هسته ی یخ زیستی، پخش یخ، خنک نگه داشتن، ترموگرافی ویدیوی مادون قرمز، آسیبدیدگی یخ زده، محیط زیست آلپ،
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک بوم شناسی، تکامل، رفتار و سامانه شناسی
چکیده انگلیسی


- Supercooling of reproductive shoots provides frost protection.
- Supercooling is maintained by histological ice barriers at the pedicel base.
- Ice barriers are active at all reproductive stages (bud, anthesis, and fruit).

Over-wintering reproductive buds of many woody plants survive frost by supercooling. The bud tissues are isolated from acropetally advancing ice by the presence of ice barriers that restrict ice growth. Plants living in alpine environments also face the risk of ice formation in summer months. Little knowledge exists, how reproductive structures of woody alpine plants are protected from frost injury during episodic summer frosts. In order to address this question, frost resistance of three common dwarf shrubs, Calluna vulgaris, Empetrum hermaphroditum and Loiseleuria procumbens was measured and ice formation and propagation were monitored in twigs bearing reproductive shoots during various stages of reproductive development (bud, anthesis, and fruit) throughout the alpine summer. Results indicated that, in the investigated species, ice barriers were present at all reproductive stages, isolating the reproductive shoots from ice advancing from the subtending vegetative shoot. Additionally, in the reproductive stems ice nucleating agents that are active at warm, sub-zero temperatures, were absent. The ice barriers were 100% effective, with the exception of L. procumbens, where in 13% of the total observations, the ice barrier failed. The ice barriers were localized at the base of the pedicel, at the anatomical junction of the vegetative and reproductive shoot. There, structural aspects of the tissue impede or prevent ice from advancing from the frozen stem into the pedicel of the reproductive shoot. Under the experimental conditions used in this study, ice nucleation initially occurred in the stem of the vegetative shoot at species-specific mean temperatures in the range of −4.7 to −5.8 °C. Reproductive shoots, however, remained supercooled and ice free down to a range of −7.2 to −18.2 °C or even below −22 °C, the lowest temperature applied in the study. This level of supercooling is sufficient to prevent freezing of reproductive structures at the lowest air temperature occurring at the altitude of the upper distribution boundary of the natural habitat of the investigated species which is between −8 and −10 °C in summer. Frost resistance assays indicated that reproductive shoots are much less frost resistant than vegetative stems, and in contrast to vegetative shoots, are not ice tolerant. Supercooling of reproductive shoots in alpine, woody plant species is an effective mechanism that protects developing offspring from potential frost damage resulting from episodic summer freezing events.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Environmental and Experimental Botany - Volume 106, October 2014, Pages 4-12
نویسندگان
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