in this study, the possible infection of thomson navel, moro blood sweet orange, page mandarin and webber pomelo with citrus viroids was investigated. biological indexing was performed by grafting on etrog citron (c. medica) and maintained in temperature-controlled greenhouse. after inoculation, rna was extracted by sds– potassium acetate method. detection of citrus viroids was done reverse tra...

Citrus species grown in Japan are affected by several viruses and viroids, including satsuma dwarf virus, citrus vein enation exocortis viroid, other viroids. Recently, a comprehensive review was made on the occurrence, history, research of following three major Japan: tatter leaf virus (apple stem grooving virus), tristeza (Iwanami 2022). As sequel, this study reviews development viroids as we...

The Sudanese citrus industry is mainly based on oldline cultivars of grapefruit, sweet orange and willow leaf mandarin, grafted almost exclusively on sour orange. Infection with graft-transmissible agents, viroids in particular, may have deleterious effects on the productivity of these citrus species and, more importantly, limits the choice of rootstocks should sour orange be replaced by altern...

Viroids are small (246-401 nucleotides), single-stranded, circular RNA molecules that infect several crop plants and can cause diseases of economic importance. Citrus are the hosts in which the largest number of viroids have been identified. Citrus exocortis viroid (CEVd), the causal agent of citrus exocortis disease, induces considerable losses in citrus crops. Changes in the gene expression p...

gummy bark disease of sweet orange (citrus sinensis) trees has been reported from a few citrus growing regions of the world. the disease symptoms consist of mild to severe stem pitting and brown gummy flecks in the bark of sweet orange trees on sour orange ( c. aurantium) rootstock, being conspicuous several centimeter above the bud :union: on the trunk. the pits were usually impregnated with b...

background and aims: citrus exocortis disease is naturally limited to citrus plants and causes a serious disease on sensitive rootstocks such as trifoliate orange. the aim of this study was to sample new variants of citrus exocortis viroid from fars trees with yellowing and suberization symptoms and comparison with other isolates of this viroid. materials and methods: a number of symptomatic or...

Viroids are the smallest agents known to be pathogenic to plants. Unlike viruses, they are devoid of a protective protein coat and are composed entirely of circular ribonucleic acid of low molecular weight (ca. 85,000-130,000 d. In spite of their small size, viroids cause serious diseases of avocado, chrysanthemum, citrus, coconut, cucumber, hop, potato and tomato. Although viroid diseases have...

Figure 1 Figure 2 Citrus fruits are traditional agricultural products in Egypt. Citrus volkameriana is the best rootstock for growing citrus in Egypt’s desert areas (newly reclaimed land). It is far superior to other rootstocks used in Egypt in its resistance to Citrus tristeza virus as well as its tolerance to drought. Constraints to fruit production are mainly related to tree decline caused b...

Due to their small size, locating pathogenic RNAs, such as viroids, in plant tissue and cell organelles has been difficult. Viroids are circular single-stranded RNA virus-like pathogens that reduce growth, vigor, yield economically important crops potato, tomato, hops citrus. Viroid infections plants largely diagnosed by dot blot hybridization, PAGE-gels, or RT-PCR. Because traditional situ hyb...

Background and Aims: Viroids are smallest known plant pathogens and cause several economically significant diseases. Until recently, viroid detection relied mainly on biological tests and indexing. Today various diagnostic techniques such as nucleic acid hybridization, southern blot and reverse transcription coupled with polymerase chain reaction (RT-PCR) are being used for detection and diagno...