E. Shabi

Bio: E. Shabi is an academic researcher from Agricultural Research Organization, Volcani Center. The author has contributed to research in topics: Benomyl & Population. The author has an hindex of 11, co-authored 15 publications receiving 862 citations.

Characterization of Colletotrichum species responsible for anthracnose diseases of various fruits.

Abstract: ilamentous fungi of the genus Colletotrichum and its teleomorph Glomerella are considered major plant pathogens worldwide. They cause significant economic damage to crops in tropical, subtropical, and temperate regions. Cereals, legumes, ornamentals, vegetables, and fruit trees may be seriously affected by the pathogen (3). Although many cultivated fruit crops are infected by Colletotrichum species, the most significant economic losses are incurred when the fruiting stage is attacked. Colletotrichum species cause typical disease symptoms known as anthracnose, characterized by sunken necrotic tissue where orange conidial masses are produced. Anthracnose diseases appear in both developing and mature plant tissues (4). Two distinct types of diseases occur: those affecting developing fruit in the field (preharvest) and those damaging mature fruit during storage (postharvest). The ability to cause latent or quiescent infections has grouped Colletotrichum among the most important postharvest pathogens. Species of the pathogen appear predominantly on aboveground plant tissues; however, belowground organs, such as roots and tubers, may also be affected. In this article, we deal in particular with methods used to identify and characterize Colletotrichum species and genotypes from almond, avocado, and strawberry, as examples, using traditional and molecular tools. The three pathosystems chosen represent different disease patterns of fruitassociated Colletotrichum. Multiple Species on a Single Host Numerous cases have been reported in which several Colletotrichum species or biotypes are associated with a single host. For example, avocado and mango anthracnose, caused by both C. acutatum and C. gloeosporioides, affect fruit predominantly as postharvest diseases (25,40,41). Strawberry may be infected by three Colletotrichum species, C. fragariae, C. acutatum, and C. gloeosporioides, causing anthracnose of fruit and other plant parts (31). Almond and other deciduous fruits may be infected by C. acutatum or C. gloeosporioides (Table 1) (1,5,46,50). Citrus can be affected by four different Colletotrichum diseases (61): postbloom fruit drop and key lime anthracnose, both caused by C. acutatum, and shoot dieback and leaf spot, and postharvest fruit decay, both caused by C. gloeosporioides. Additional examples of hosts affected by multiple Colletotrichum species include coffee, cucurbits, pepper, and tomato. Single Species on Multiple Hosts It is common to find that a single botanical species of Colletotrichum infects multiple hosts. For example, C. gloeosporioides (Penz.) Penz. & Sacc. in Penz. (teleomorph: Glomerella cingulata (Stoneman) Spauld. & H. Schrenk), which is considered a cumulative species and forms the sexual stage in some instances, is found on a wide variety of fruits, including almond, avocado, apple, and strawberry (Table 2) (6,15,31,46). Likewise, C. acutatum J.H. Simmonds has been reported to infect a large number of fruit crops, including avocado, strawberry, almond, apple, and peach (1,5,16,25,27). Examples of other species with multiple host ranges include C. coccodes, C. capsici, and C. dematium (14,56).

Molecular Analyses of Colletotrichum Species from Almond and Other Fruits

Abstract: Isolates of Colletotrichum spp. from almond, avocado, and strawberry from Israel and isolates of the pink subpopulation from almond from the United States were characterized by various molecular methods and compared with morphological identification. Taxon-specific primer analysis grouped the avocado isolates within the species C. gloeosporioides and the U.S. almond and Israeli strawberry isolates within the species C. acutatum. However, the Israeli almond isolates, previously identified morphologically as C. gloeosporioides, reacted with C. acutatum-specific primers. Arbitrarily primed polymerase chain reaction and A+T-rich DNA analyses determined that each population from almond and strawberry was distinct and clonal. Sequence analysis of the complete internal transcribed spacer (ITS) region (ITS 1–5.8S–ITS 2) revealed a similarity of between 97.03 and 98.72% among almond isolates from Israel, C. acutatum almond isolates from the United States, and C. acutatum strawberry isolates from Israel. S...

Characterization of Colletotrichum gloeosporioides isolates from avocado and almond fruits with molecular and pathogenicity tests.

Abstract: One hundred twenty isolates of Colletotrichum gloeosporioides from avocado (6 U.S. and 57 Israeli isolates) and almond (57 Israeli isolates) fruits were compared by various molecular methods and a pathogenicity assay in order to determine the genetic diversity and host specificity between and among the different populations. DNA from eight additional U.S. almond anthracnose isolates were also compared. PCR amplification of genomic DNA with four primers produced uniform banding patterns for all the Israeli almond isolates from different geographic locations in Israel. DNAs from the U.S. almond isolates were distinct from DNAs of the Israeli isolates. In contrast, the avocado isolates from Israel and the United States were more diverse, with numerous arbitrarily primed-PCR phenotypes being observed. HaeIII digestion patterns of A+T-rich DNA distinguished between the almond and avocado isolates. Southern hybridization of the repetitive nuclear-DNA element GcpR1 to PstI-digested genomic DNA of almond and avocado isolates revealed no polymorphic fragments among the almond isolates, whereas polymorphic fragments were observed among the avocado isolates. Amplification and subsequent restriction enzyme digestion of the internal transcribed spacer 4 and 5 regions between the small and large nuclear subunits of DNA encoding rRNA failed to distinguish between C. gloeosporioides isolates from a diverse host range. In artificial inoculations, avocado isolates produced various lesions on avocado and almond fruits, whereas the almond isolates infected both fruits at a lower rate.

Characterization of Colletotrichum acutatum causing anthracnose of anemone (Anemone coronaria L.)

Abstract: Anthracnose, or leaf-curl disease of anemone, caused by Colletotrichum sp., has been reported to occur in Australia, western Europe, and Japan. Symptoms include tissue necrosis, corm rot, leaf crinkles, and characteristic spiral twisting of floral peduncles. Three epidemics of the disease have been recorded in Israel: in 1978, in 1990 to 1993, and in 1996 to 1998. We characterized 92 Colletotrichum isolates associated with anthracnose of anemone (Anemone coronaria L.) for vegetative compatibility (72 isolates) and for molecular genotype (92 isolates) and virulence (4 isolates). Eighty-six of the isolates represented the three epidemics in Israel, one isolate was from Australia, and five isolates originated from western Europe. We divided these isolates into three vegetative-compatibility groups (VCGs). One VCG (ANE-A) included all 10 isolates from the first and second epidemics, and 13 of 62 examined isolates from the third epidemic in Israel, along with the isolate from Australia and 4 of 5 isolates from Europe. Another VCG (ANE-F) included most of the examined isolates (49 of the 62) from the third epidemic, as well as Colletotrichum acutatum from strawberry, in Israel. Based on PCR amplification with species-specific primers, all of the anemone isolates were identified as C. acutatum. Anemone and strawberry isolates of the two VCGs were genotypically similar and indistinguishable when compared by arbitrarily primed PCR of genomic DNA. Only isolate NL-12 from The Netherlands, confirmed as C. acutatum but not compatible with either VCG, had a distinct genotype; this isolate represents a third VCG of C. acutatum. Isolates from anemone and strawberry could infect both plant species in artificial inoculations. VCG ANE-F was recovered from natural infections of both anemone and strawberry, but VCG ANE-A was recovered only from anemone. This study of C. acutatum from anemone illustrates the potential of VCG analysis to reveal distinct subspecific groups within a pathogen population which appears to be genotypically homogeneous by molecular assays.

Negative cross resistance between benzimidazole and N‐phenylcarbamate fungicides and control of Botrytis cinerea on grapes

Abstract: Isolates of Botrytis cinerea resistant to benzimidazoles (BenR), dicarboximides (DicR), or both (BenR DicR) were found on table grapes in vineyards in Israel. In vineyards treated for one or two seasons with benomyl and dicarboximides, 41% of the isolates were benomyl-resistant, 18% were dicarboximide-resistant and 21 % were resistant to both fungicides. The frequency of resistant strains was very low in non-treated vineyards. Negatively correlated cross resistance (NCCR) was manifested by 46 BenR isolates which were sensitive to isopropyl N-(3,4-diethoxyphenyl) carbamate (NPC) and 73 benomyl-sensitive (Bens) isolates which were insensitive to NPC; NCCR was not influenced by sensitivity to dicarboximides. A mixture of Bens DicR plus BenR Dics isolates, inoculated on rose petals, was inhibited by mixtures of benzimidazoles plus NPC but not by benomyl, NPC or iprodione alone. Grey mould, incited on maturing grape berries by a vineyard population composed of Bens and BenR strains, was not controlled by benomyl, while the mixture of NPC plus carbendazim was effective.

Characterization of Colletotrichum species responsible for anthracnose diseases of various fruits.

Abstract: ilamentous fungi of the genus Colletotrichum and its teleomorph Glomerella are considered major plant pathogens worldwide. They cause significant economic damage to crops in tropical, subtropical, and temperate regions. Cereals, legumes, ornamentals, vegetables, and fruit trees may be seriously affected by the pathogen (3). Although many cultivated fruit crops are infected by Colletotrichum species, the most significant economic losses are incurred when the fruiting stage is attacked. Colletotrichum species cause typical disease symptoms known as anthracnose, characterized by sunken necrotic tissue where orange conidial masses are produced. Anthracnose diseases appear in both developing and mature plant tissues (4). Two distinct types of diseases occur: those affecting developing fruit in the field (preharvest) and those damaging mature fruit during storage (postharvest). The ability to cause latent or quiescent infections has grouped Colletotrichum among the most important postharvest pathogens. Species of the pathogen appear predominantly on aboveground plant tissues; however, belowground organs, such as roots and tubers, may also be affected. In this article, we deal in particular with methods used to identify and characterize Colletotrichum species and genotypes from almond, avocado, and strawberry, as examples, using traditional and molecular tools. The three pathosystems chosen represent different disease patterns of fruitassociated Colletotrichum. Multiple Species on a Single Host Numerous cases have been reported in which several Colletotrichum species or biotypes are associated with a single host. For example, avocado and mango anthracnose, caused by both C. acutatum and C. gloeosporioides, affect fruit predominantly as postharvest diseases (25,40,41). Strawberry may be infected by three Colletotrichum species, C. fragariae, C. acutatum, and C. gloeosporioides, causing anthracnose of fruit and other plant parts (31). Almond and other deciduous fruits may be infected by C. acutatum or C. gloeosporioides (Table 1) (1,5,46,50). Citrus can be affected by four different Colletotrichum diseases (61): postbloom fruit drop and key lime anthracnose, both caused by C. acutatum, and shoot dieback and leaf spot, and postharvest fruit decay, both caused by C. gloeosporioides. Additional examples of hosts affected by multiple Colletotrichum species include coffee, cucurbits, pepper, and tomato. Single Species on Multiple Hosts It is common to find that a single botanical species of Colletotrichum infects multiple hosts. For example, C. gloeosporioides (Penz.) Penz. & Sacc. in Penz. (teleomorph: Glomerella cingulata (Stoneman) Spauld. & H. Schrenk), which is considered a cumulative species and forms the sexual stage in some instances, is found on a wide variety of fruits, including almond, avocado, apple, and strawberry (Table 2) (6,15,31,46). Likewise, C. acutatum J.H. Simmonds has been reported to infect a large number of fruit crops, including avocado, strawberry, almond, apple, and peach (1,5,16,25,27). Examples of other species with multiple host ranges include C. coccodes, C. capsici, and C. dematium (14,56).

A polyphasic approach for studying Colletotrichum

Abstract: Colletotrichum is the causal agent of anthracnose and other diseases on leaves, stems and fruits of numerous plant species, including several important crops. Accurate species identification is critical to understand the epidemiology and to develop effective control of these diseases. Morphologically-based identification of Colletotrichum species has always been problematic, because there are few reliable characters and many of these characters are plastic, dependent upon methods and experimental conditions. Rapid progress in molecular phylogenetic methods is now making it possible to recognise stable and well-resolved clades within Colletotrichum. How these should be reflected in a classification system remains to be resolved. An important step in providing a stable taxonomy for the genus is to epitypify existing names, and in so doing link them to genetically defined clades. We recommend a polyphasic approach to the recognition and identification of species within Colletotrichum, matching genetic distinctness with informative morphological and biological characters. This paper reviews various approaches in the study of Colletotrichum complexes including morphology, pathogenicity, physiology, phylogenetics and secondary metabolite production. A backbone phylogenetic tree using ITS sequence data from 42 ex-type specimens has been generated. Phylogenetic analysis using ITS sequence data is a useful tool to give a preliminarily identification for Colletotrichum species or place them in species complexes. However, caution must be taken here as the majority of the ITS sequences deposited in GenBank are wrongly named. Multi-gene phylogenetic data provides much better understanding of the relationships within Colletotrichum and should be employed where possible. We propose that an ideal approach for Colletotrichum systematics should be based on a multi-gene phylogeny, with comparison made with type specimens, and a well-defined phylogenetic lineage should be in conjunction with recognisable polyphasic characters, such as morphology, physiology, pathogenicity, cultural characteristics and secondary metabolites. Finally a set of protocols and methodologies is provided as a guideline for future studies, epitypification and the description of new species.

Characterization and pathogenicity of Colletotrichum species associated with anthracnose on chilli (Capsicum spp.) in Thailand

Abstract: Fungal isolates from chilli (Capsicum spp.) fruits in Thailand that showed typical anthracnose symptoms were identified as Colletotrichum acutatum, C. capsici and C. gloeosporioides. Phylogenetic analyses from DNA sequence data of ITS rDNA and β-tubulin (tub2) gene regions revealed three major clusters representing these three species. Among the morphological characters examined, colony growth rate and conidium shape in culture were directly correlated with the phylogenetic groupings. Comparison with isolates of C. gloeosporioides from mango and C. acutatum from strawberry showed that host was not important for phylogenetic grouping. Pathogenicity tests validated that all three species isolated from chilli were causal agents for chilli anthracnose when inoculated onto fruits of the susceptible Thai elite cultivar Capsicum annuum cv. Bangchang. Cross-infection potential was shown by C. acutatum isolates originating from strawberry, which produced anthracnose on Bangchang. Interestingly, only C. acutatum isolates from chilli were able to infect and produce anthracnose on PBC 932, a resistant genotype of Capsicum chinense. This result has important implications for Thai chilli breeding programmes in which PBC 932 is being hybridized with Bangchang to incorporate anthracnose resistance into chilli cultivars.

Host Range Specificity in Verticillium dahliae.

Abstract: Verticillium dahliae isolates from artichoke, bell pepper, cabbage, cauliflower, chili pepper, cotton, eggplant, lettuce, mint, potato, strawberry, tomato, and watermelon and V. albo-atrum from alfalfa were evaluated for their pathogenicity on all 14 hosts. One-month-old seedlings were inoculated with a spore suspension of about 10(7) conidia per ml using a root-dip technique and incubated in the greenhouse. Disease incidence and severity, plant height, and root and shoot dry weights were recorded 6 weeks after inoculation. Bell pepper, cabbage, cauliflower, cotton, eggplant, and mint isolates exhibited host specificity and differential pathogenicity on other hosts, whereas isolates from artichoke, lettuce, potato, strawberry, tomato, and watermelon did not. Bell pepper was resistant to all Verticillium isolates except isolates from bell pepper and eggplant. Thus, host specificity exists in some isolates of V. dahliae. The same isolates were characterized for vegetative compatibility groups (VCGs) through complementation of nitrate nonutilizing (nit) mutants. Cabbage and cauliflower isolates did not produce nit mutants. The isolate from cotton belonged to VCG 1; isolates from bell pepper, eggplant, potato, and tomato, to VCG 4; and the remaining isolates, to VCG 2. These isolates were also analyzed using the random amplified polymorphic DNA (RAPD) method. Forty random primers were screened, and eighteen of them amplified DNA from Verticillium. Based on RAPD banding patterns, cabbage and cauliflower isolates formed a unique group, distinct from other V. dahliae and V. albo-atrum groups. Minor genetic variations were observed among V. dahliae isolates from other hosts, regardless of whether they were host specific or not. There was no correlation among pathogenicity, VCGs, and RAPD banding patterns. Even though the isolates belonged to different VCGs, they shared similar RAPD profiles. These results suggest that management of Verticillium wilt in some crops through crop rotation is a distinct possibility.