Identification of Arthrinium marii as Causal Agent of Olive Tree Dieback in Apulia (Southern Italy)

Understanding the role of bats as fungal vectors in the environment

Bats (Chiroptera), the second largest group of mammals, are known for their unique immune system and their ability to act as vectors for various zoonoses. Bats also act as important carriers of fungi, which include plant, animal, and human pathogens. Their roosting areas, foraging behaviors, and even migration routes make bats ideal vectors for fungi. We isolated 75 culturable fungal species from bats in Yunnan Province, China, with 36 species representing known pathogens of plants, animals, and humans, while 39 species are non-pathogenic fungi. Among these species, 77% (58 species) belonged to Ascomycota, 9% (seven species) belonged to Basidiomycota, and 13% (10 species) belonged to Mucoromycota. Even though several taxonomic studies on fungi associated with bats have been published, studies exploring the role of bats as fungal vectors are lacking. This study discusses the fungi host-specific traits and pathogenicity and the impact and ecological significance of bats as fungal vectors.

Three new endophytic Apiospora species (Apiosporaceae, Amphisphaeriales) from China

Apiospora species are widely distributed fungi with diverse lifestyles, primarily functioning as plant pathogens, as well as exhibiting saprophytic and endophytic behaviors. This study reports the discovery of three new species of Apiospora, namely A.gongcheniae, A.paragongcheniae, and A.neogongcheniae, isolated from healthy Poaceae plants in China. These novel species were identified through a multi-gene phylogenetic analysis. The phylogenetic analysis of the combined ITS, LSU, tef1, and tub2 sequence data revealed that the three new species formed a robustly supported clade with A.garethjonesii, A.neogarethjonesii, A.setostroma, A.subrosea, A.mytilomorpha, and A.neobambusae. Detailed descriptions of the newly discovered species are provided and compared with closely related species to enhance our understanding of the genus Apiospora.

Characterization of Coniella granati Isolates Causing Pomegranate Decline in Italy

Coniella granati, the causal agent of pomegranate crown rot, twig blight, and fruit decay, is an emerging worldwide pathogen with a heavy impact on pomegranate cultivation. In this study, we report the rapid spread of the fungus in Italian pomegranate orchards associated with crown rot symptoms and provide new results on fungal development, baseline sensitivity to different fungicides, and intraspecific variability by analyzing 11 isolates, representative of populations of the pathogen from comparable pomegranate orchards in different regions of Italy. In vitro assays showed that 25 to 30°C was the optimal range for both colony growth and conidial germination, corroborating the results previously obtained for Californian and Greek isolates. According to the baseline sensitivity assay on the response of colony growth and conidial germination to 10 fungicides, fludioxonil, thiophanate-methyl, tebuconazole, and cyprodinil were the most effective. Random amplified polymorphic DNA (RAPD) analysis, carried out using fourteen 10-mer primers, showed very low intraspecific variability (similarity coefficient >0.95), probably as a result of the recent spread of the pathogen in Italy and the uncommon occurrence of the sexual process as a source of genetic variability. In summary, this study provides new knowledge on C. granati that will be helpful for improving pomegranate crown rot management.

Identification and Characterization of Neofusicoccum stellenboschiana in Branch and Twig Dieback-Affected Olive Trees in Italy and Comparative Pathogenicity with N. mediterraneum

For about a decade, olive groves in Apulia (Southern Italy) have been progressively destroyed by Olive Quick Decline Syndrome (OQDS), a disease caused by the bacterium Xylella fastidiosa subsp. pauca (Xfp). Recently, we described an additional wilting syndrome affecting olive trees in that area. The botryosphaeriaceous fungus Neofusicoccum mediterraneum was found associated with the diseased trees, and its high virulence toward olive trees was demonstrated. Given the common features with Branch and Twig Dieback (BTD) of olive tree, occurring in Spain and California, we suggested that the observed syndrome was BTD. During our first survey, we also found a botryosphaeriaceous species other than N. mediterraneum. In the present article, we report the morphological and molecular characterization of this fungal species which we identified as Neofusicoccum stellenboschiana. In the study, we also included for comparison additional N. stellenboschiana isolates obtained from olive trees in Latium and Tuscany region (Central Italy). The occurrence of N. stellenboschiana in olive trees is reported here for the first time in the northern hemisphere. The pathogenicity and virulence were tested in nine inoculation trials, where the Apulian N. stellenboschiana isolate was compared with the isolate from Latium and with the Apulian isolate of N. mediterraneum. Both isolates of N. stellenboschiana proved pathogenic to olive trees. They caused evident bark canker and wood discolouration when inoculated at the base of the stem of two/three-year-old trees and on one-year-old twigs. However, virulence of N. stellenboschiana was significantly lower, though still remarkable, compared with N. mediterraneum in term of necrosis progression in the bark and the wood and capacity of wilting the twigs. Virulence of N. stellenboschiana and N. mediterraneum did not substantially change when inoculations were performed in spring/summer and in autumn, suggesting that these fungal species have the potential to infect and damage olive trees in all seasons. The high thermotolerance of N. stellenboschiana was also revealed with in vitro growth and survival tests. The high virulence of these Botryosphaeriaceae species highlights their contribution in BTD aetiology and the necessity to investigate right away their diffusion and, possibly, the role of additional factors other than Xfp in the general decline of olive groves in Apulia. Hence the importance of assessing the degree of overlap of BTD/Botryosphariaceae with OQDS/Xfp is discussed.

Insight into the Taxonomic Resolution of Apiospora: Introducing Novel Species and Records from Bamboo in China and Thailand

Taxonomic studies of bambusicolous fungi in China and Thailand have resulted in the collection of three fascinating saprobic coelomycetes strains. Morphology coupled with combined gene analysis of ITS, LSU, TUB2, and TEF1-α DNA sequence data showed that they belong to the genus Apiospora, family Apiosporaceae. A new species from Thailand, Apiospora mukdahanensis, and new records of A. locuta-pollinis from China are herein described. In addition, based on both morphological data coupled with phylogenetics and nomenclatural analyses, A. mori is proposed as a new combination. Maximum likelihood, maximum parsimony and Bayesian analyses were performed to clarify the phylogenetic affinities of the species obtained in this study. Newly obtained strains are compared with morphologically- and phylogenetically-related taxa. The comprehensive descriptions, illustrations, and updated phylogeny are provided and discussed for intra-and intergeneric relationships within Apiospora species.

One New Species and Two New Host Records of Apiospora from Bamboo and Maize in Northern Thailand with Thirteen New Combinations

The genus Apiospora is known as a cosmopolitan genus, found across various substrates. In this study, four Apiospora taxa were obtained from the decaying stems of bamboo and maize in northern Thailand. Apiospora collections were compared with known species based on the morphological characteristics and the DNA sequence data of internal transcribed spacer (ITS), the partial large subunit nuclear rDNA (LSU), the translation elongation factor 1-alpha gene (TEF1-α) and beta-tubulins (TUB2). Apiospora chiangraiense sp. nov. and two new host records (Ap. intestini and Ap. rasikravindra) are introduced here based on the morphological characteristics and multi-locus analyses. Additionally, thirteen species previously identified as Arthrinium are introduced as new combinations in Apiospora, viz., Ap. acutiapica, Ap. bambusicola, Ap. biserialis, Ap. cordylines, Ap. cyclobalanopsidis, Ap. euphorbiae, Ap. gelatinosa, Ap. locuta-pollinis, Ap. minutispora, Ap. pseudorasikravindrae, Ap. septate, Ap. setariae and Ap. sorghi.