Effects of phloem on canopy dieback, tested with manipulations and a canker pathogen in the Corylus avellana/Anisogramma anomala host/pathogen system

Abstract Canker pathogens cause necrosis of the phloem, but in many host/pathogen systems, they also cause canopy dieback, which implicates xylem, not phloem dysfunction. We hypothesize that this dieback distal to the canker is caused by water stress resulting from the lack of a phloem-to-xylem connection, which in a healthy plant would allow delivery of nonstructural carbohydrates (NSCs) and water inward to aid in xylem embolism refilling. We tested several components of this hypothesis in the host/pathogen system Corylus avellana L./Anisogramma anomala (Peck) E. Müll (Eastern filbert blight). Cankers were non-girdling and usually ≥0.1 m long. As expected, healthy controls had higher specific conductivity (Ks) than diseased stems, but unexpectedly, had similar moisture content (m.c.), showing that the lower Ks did not result from more embolisms in the diseased stems. Moreover, manipulations that removed cambium and phloem to simulate a canker, or that shaded stems to lower NSCs, did not result in lower Ks or m.c. than controls. The outer millimeter of xylem adjacent to a canker had infrequent tyloses and/or fungal hyphae in many but not all samples, and dye studies showed little xylem water transport in that region, but the incidence of these blockages was insufficient to cause the observed 19% decrease in Ks. Healthy stems had higher m.c. than diseased stems above the canker (or analogous) location and were longer for the same leaf weight, suggestive of water stress in the upper portion of diseased stems. These results suggest that dieback distal to cankers in this system results from the bottleneck in water transport in the region adjacent to a canker, but did not find evidence to support the requirement of a phloem-to-xylem connection for continued water transport.

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Drought responses in six hazelnut (Corylus avellana L.) cultivars

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Horticulture ◽

10.15835/buasvmcn-hort:12288 ◽

2016 ◽

Vol 73 (2) ◽

pp. 259

Author(s):

Ali Shahi-Gharahlar ◽

Mohammad Reza Fatahi ◽

Zabihollah Zamani ◽

Mohamad Al Hassan ◽

Monica Boscaiu ◽

...

Keyword(s):

Oxidative Stress ◽

Water Stress ◽

Biochemical Markers ◽

Crop Yields ◽

Corylus Avellana ◽

Initial Attempt ◽

Stress Treatment ◽

Reliable Marker ◽

Corylus Avellana L ◽

And Oxidative Stress

Drought is one of the major causes of reduction of crop yields worldwide, a problem that will increase in the next decades due to climate change. We describe here an initial attempt to define biochemical markers associated to water stress in several hazelnut cultivars, by measuring the levels of common osmolytes and the generation of secondary oxidative stress, in plants subjected to water stress, and after recovery from the stress treatment. Proline appears to be a reliable marker in this species, as its accumulation in leaves correlates well with the degree of stress affecting the plants. Differences between cultivars in relative Pro accumulation and oxidative stress suggested that some cultivars are more tolerant than others and could be selected for cultivation in drought-affected areas

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Ecological plasticity of nut crops of the collections of the federal scientific center for agroecology RAS

World Ecology Journal ◽

10.25726/nm.2019.40.59.006 ◽

2019 ◽

pp. 105-115

Author(s):

А.Ш. Хужахметова

Keyword(s):

Corylus Avellana ◽

Taxonomic Composition ◽

Morphological Features ◽

Scientific Center ◽

Significance Level ◽

Ecological Plasticity ◽

Protective Forest ◽

Corylus Avellana L ◽

Academy Of Sciences ◽

Trees And Shrubs

Показана актуальность изучения экологической пластичности древесных растений в связи с необходимостью подбора адаптированного видового состава деревьев и кустарников для защитных лесных насаждений в условиях климатических изменений. Установлено, что экологическая пластичность и пределы толерантности растений связаны со свойством организмов адаптироваться к тому или иному диапазону факторов среды. В статье представлен таксономический состав орехоплодных культур коллекций ФНЦ агроэкологии РАН. Это шесть видов рода Juglans: J. regia, J. mandshurica, J. cinerea, J. rupestris, J. ailanthifolia, J. nigra и три вида рода Corylus: С. avellana L., С. аmericana W., сорта С. pontica C. Koch Президент, Футкурами, Черкесский2. Приведены сведения о положительном опыте культивирования Corylus avellana L. в плантационных насаждениях (1,6 га, посадка рядовая, схема размещения 55 м) в условиях южных черноземов. Цель исследований изучить экологическую пластичность орехоплодных кустарников коллекций ФНЦ агроэкологии РАН. На примере родового комплекса Corylus получены материалы по экологической пластичности орехоплодных кустарников в условиях каштановых (кадастр. 34:36:0000:14:0178), светлокаштановых почв (34:34:000000:122 34:34:060061:10). Установлены уровни изменчивости морфологических признаков ассимиляционного аппарата и плодов С. avellana L., сортов С. pontica C. Koch., которые согласуются с зимо и засухоустойчивостью. Кластерный анализ позволил выявить корреляцию признаков при 5 уровне значимости. Для целей защитного лесоразведения и озеленения засушливых районов рекомендованы Corylus avellana и Черкесский2 с выраженной вариабельностью морфологических признаков, которая указывает на их широкую экологическую валентность и адаптационные возможности в рассматриваемых условиях. The urgency of studying the ecological plasticity of woody plants in connection with the need to select an adapted species composition of trees and shrubs for protective forest plantations in the context of climate change is shown. It is established that the ecological plasticity and tolerance range of plants is associated with the ability of organisms to adapt to a particular range of environmental factors. The article presents the taxonomic composition of nut crops in the collections of FSC Agroecology RAS. Six species of Juglans: J. regia, J. mandshurica, J. cinerea, J. rupestris, J. ailanthifolia, J. nigra and three species of the genus Corylus: С. avellana L., С. аmericana W., varieties of C. pontica C. Koch the President, Futkurami, Circassian2. Data on positive experience of cultivation of Corylus avellana L. in plantation plantings (1,6 hectares, landing ordinary, the scheme of placement of 55 m) in the conditions of southern chernozems are given. The purpose of the research is to study the ecological plasticity of nutbearing shrubs of the collections of the Federal scientific center for Agroecology Russian Academy of Sciences. For example, a generic complex Corylus submissions received on the environmental plasticity of nut bushes in the conditions of brown (the cadaster nubmer 34:36:0000:14:0178), light chestnut soils (34:34:000000:122 34:34:060061:10). The levels of variability of morphological features of the assimilation apparatus and fruits of Corylus avellana L., С. pontica C. Koch varieties were established., which are consistent with winter and drought resistance. Cluster analysis revealed the correlation of features at 5 significance level. Corylus avellana and Circassian2 with a pronounced variability of morphological features, which indicates their broad ecological valence and adaptation capabilities in the conditions under consideration, are recommended for the purposes of protective afforestation and greening of dry areas.

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