Grapevine Trunk Diseases (GTDs) are a major challenge to the grape industry worldwide. GTDs are responsible for considerable loss of quality, production, and vineyard longevity. Seventy-five percent of Chilean vineyards are estimated to be affected by GTDs. GTDs are complex diseases caused by several fungi species, including members of the Botryosphaeriaceae family and Phaeomoniella chlamydospora, considered some of the most important causal agents for these diseases in Chile. In this study, we isolated 169 endophytic and 209 rhizospheric fungi from grapevines grown under organic and conventional farming in Chile. Multiple isolates of Chaetomium sp., Cladosporium sp., Clonostachys rosea, Epicoccum nigrum, Purpureocillium lilacinum, and Trichoderma sp. were evaluated for their potential of biocontrol activity against Diplodia seriata, Neofusicoccum parvum, and Pa. chlamydospora. Tests of antagonism were carried out using two dual-culture-plate methods with multiple media types, including agar containing grapevine wood extract to simulate in planta nutrient conditions. Significant pathogen growth inhibition was observed by all isolates tested. Clonostachys rosea showed 98.2% inhibition of all pathogens in the presence of grapevine wood extract. We observed 100% pathogen growth inhibition when autoclaved lignified grapevine shoots were pre-inoculated with either C. rosea strains or Trichoderma sp. Overall, these results show that C. rosea strains isolated from grapevines are promising biocontrol agents against GTDs.

In the past and present, human activities have been involved in triggering global warming, causing drought stresses that affect animals and plants. Plants are more defenseless against drought stress; and therefore, plant development and productive output are decreased. To decrease the effect of drought stress on plants, it is crucial to establish a plant feedback mechanism of resistance to drought. The drought reflex mechanisms include the physical stature physiology and biochemical, cellular, and molecular-based processes. Briefly, improving the root system, leaf structure, osmotic-balance, comparative water contents and stomatal adjustment are considered as most prominent features against drought resistance in crop plants. In addition, the signal transduction pathway and reactive clearance of oxygen are crucial mechanisms for coping with drought stress via calcium and phytohormones such as abscisic acid, salicylic acid, jasmonic acid, auxin, gibberellin, ethylene, brassinosteroids and peptide molecules. Furthermore, microorganisms, such as fungal and bacterial organisms, play a vital role in increasing resistance against drought stress in plants. The number of characteristic loci, transgenic methods and the application of exogenous substances [nitric oxide, (C28H48O6) 24-epibrassinolide, proline, and glycine betaine] are also equally important for enhancing the drought resistance of plants. In a nutshell, the current review will mainly focus on the role of phytohormones and related mechanisms involved in drought tolerance in various crop plants.

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Stem canker and dieback are important factors that limit the longevity and reduce the yield of blueberry (Vaccinium spp.) in Chile. In this study, species of Diaporthe associated with blueberry were isolated and identified. The internal transcribed spacer (ITS) regions of ribosomal DNA of 30 isolates and the translation elongation factor 1-α (EF1-α) of 14 isolates were sequenced, analyzed, and compared with their morphological and pathological characteristics. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Diaporthe ambigua, D. australafricana, D. neotheicola, D. passiflorae, and Diaporthe sp. 1. However, morphology alone was insufficient to identify these species. The combined analysis of ITS and EF1-α gene sequences grouped the Chilean blueberry isolates in the same five groups obtained in the ITS analysis. Pathogenicity tests conducted with attached and detached blueberry shoots (<1 year old) and stems (1 to 2 years old) confirmed that isolates of these Diaporthe spp. were pathogenic. The symptoms were reproducible and consisted of necrotic reddish-brown cankers on blueberry shoots and stems. These isolates were capable of infecting blueberry fruit, causing a soft decay, suggesting that they were tissue nonspecific and were also pathogenic on shoots of apple, grapevine, and pear. D. australafricana was the most frequently isolated species and D. ambigua, D. australafricana, and D. passiflorae were highly virulent in shoots, stems, and fruit of blueberry. This study showed that at least four species of Diaporthe are primary pathogens, capable of causing stem canker symptoms on blueberry, and this is the first report of D. ambigua, D. neotheicola, and D. passiflorae attacking this host.

Prevalence and pathogenicity of fungi associated with grapevine trunk diseases in Chilean vineyards. Cien. Inv. Agr. 40(2): 327-339. Trunk diseases in grapevine (Vitis vinifera) have been identified as a major problem in the wine and table grape industries around the world, reducing the productivity, quality and longevity of vineyards. The present study examined 694 wood samples from the cordons and trunks of vines with trunk disease symptoms in 67 Chilean vineyards located between Copiapó (27°18' S) and Los Angeles (37°42' S). A total of 1,363 fungal isolates were obtained from diseased cordons and trunks with dark brown streaking, yellowish softspongy cankers and brown hard V-shaped cankers. Using molecular identification, a total of 12 fungal genera were identified in Chile at varying frequencies: Phaeomoniella chlamydospora (85%); Botryosphaeriaceae (56%) including Diplodia mutila, D. seriata, Neofusicoccum parvum and Spencermartinsia viticola; Inocutis sp. (47%); Diatrypaceae (Cryptovalsa ampelina and Eutypella leprosa) (4.8%); Seimatosporium botan (1.7%); Phomopsis viticola (0.4%); Cylindrocarpon sp. (0.4%); and Phaeoacremonium aleophilum (0.2%). All species were pathogenic, inducing dark brown streaking on various aged grapevine wood tissue. In conclusion, several fungal species are associated with grapevine trunk diseases in the Chilean vineyards being Pa. chlamydospora, D. seriata and Inocutis sp. the most frequent isolated species. These are pathogens that can be found alone or they can coexist in the same plant. This is the first report of Pho. viticola associated with trunk diseases in Chile.