Detection and seed transmission of Bermudagrass phytoplasma in maize in Turkey

Abstract

| INTRODUC TI ONMaize (Zea mays L.) is an annual plant in the Poaceae family and the most cultivated species in this family after wheat and rice worldwide. Maize can be grown in humid region, and 90% of the crop production is used for human and livestock feeding. Maize is grown in all the regions of Turkey, particularly in the two provinces of Adana and Kahramanmaraş that produce 1,274,428 tonnes and 615,247 tonnes, respectively, composing 7.2% of the Turkish production (Anonymous, 2016). During April and May 2016, several surveys were carried out in cornfields of Adana province, wherein maize plants showing leaf yellowing, short internodes, bushy growth, dwarfing and small corncob symptoms were observed. Bermudagrass [Cynodon dactylon (L.) Pers] and Johnson grass (Sorgum halepense (L.) plants, cohabiting with corn plants with white leaf symptoms, were also observed in the inspected fields.Molecular tests demonstrated that all these plants were infected by the Bermudagrass white leaf phytoplasma. This phytoplasma mainly affects monocotyledonous plants and corn in Turkey, and its presence is associated with streaks on the leaves ranging from light green to yellow, large chlorotic areas and white discolorations, axillary shoots proliferation, stunted growth, reduced leaf size, shortened stolon and rhizome death of symptomatic plants.These symptoms were yearly occurring in many different regions, threatening the maize plantation and production. Accordingly, this research was conducted to verify some of the epidemiological Abstract During 2017, maize cultivation areas in the provinces of Adana and Kahramanmaraş (Turkey) were surveyed to inspect maize plants with symptoms similar to those associated with of phytoplasma disease, that is, yellowing, short internodes and small corncobs. Thirty fields were inspected and two hundred samples from symptomatic and asymptomatic plants were collected, together with insects considered as potential vectors of phytoplasmas. All samples were assayed by polymerase chain reaction (PCR) and subsequently analysed by restriction fragment length polymorphism and sequencing to identify the phytoplasmas detected in the plant material and insects.Results of laboratory assays and phylogenetic analyses showed that the Bermudagrass white leaf phytoplasma ('Candidatus Phytoplasma cynodontis') was present in both maize plants and seeds, showing 99% sequence identity with other reported phytoplasma strains from GenBank, whereas no PCR amplifications were obtained from tested insects. The seeds of infected plants, sown in an insect-proof screenhouse, produced plantlets that were found PCR-positive for the Bermudagrass white leaf phytoplasma, indicating its seed transmission. K E Y W O R D S

History and Current Status of Phytoplasma Diseases in the Middle East

“…The most cultivated cereals are wheat, rice, rye, barley, corn, and sorghum. Maize was found to be associated with the 16SrVI-H in Iran and 16SrXIV-A in Turkey [ 129 ]. In addition, phytoplasmas belonging to subgroup 16SrVI-A were found in sorghum plants that were grown in northwest of Iran [ 130 ].…”

First report of 'Candidatus Phytoplasma trifolii' associated with leaf reddening and upright growth in pears (Pyrus communis L.)

“…In recent years, numerous phytoplasma survey studies have been completed in economically important crops and on their surrounding weeds in different geographical regions of Turkey (Alp et al 2016;Oksal et al 2017;Kaçar et al 2019;Gazel et al 2020;Oksal 2020). These surveys revealed the presence of phytoplasma agents belonging to different phytoplasma groups including 16Sr I (Aster yellows), II (Peanut witches' broom), V (Elm yellows), VI (Clover proliferation), IX (Pigeon pea witches' broom), X (Apple proliferation), XII (Stolbur), and XIV (Bermudagrass white leaf ) (Canik & Ertunç 2007;Ertunc et al 2015;Özdemir & Çağırgan 2015;Usta et al 2017;Çağlar et al 2019).…”

Maize (Zea mays L.): A New Host for Ligustrum witches’ Broom Phytoplasma

“…Pathogens 2021, 10, x FOR PEER REVIEW 2 of 8 from maize in the country [6,8]. Although many investigations were conducted on hundreds of maize plants from different regions of Turkey, all were unsuccessful in detecting any presence of phytoplasma on this crop (Çağlar B.K., personal communication).…”

“…In Turkey, phytoplasmas are considered among the most important pathogens that are limiting the agricultural production at the national level [4]. The recent discovery of many phytoplasma groups (16SrI, II, VI, IX, X and XII) on many crops such as tomato, cucumber, pepper, maize, peach, pear, pomegranates, eggplant, sesame and ornamentals, in different regions of the country [5][6][7][8][9][10][11][12][13], along with their insect vectors, has increased concern about the potential threat of these pathogens in the very short term to come. To the best of our knowledge, only Bermudagrass white leaf phytoplasma has been reported from maize in the country [6,8].…”

“…The recent discovery of many phytoplasma groups (16SrI, II, VI, IX, X and XII) on many crops such as tomato, cucumber, pepper, maize, peach, pear, pomegranates, eggplant, sesame and ornamentals, in different regions of the country [5][6][7][8][9][10][11][12][13], along with their insect vectors, has increased concern about the potential threat of these pathogens in the very short term to come. To the best of our knowledge, only Bermudagrass white leaf phytoplasma has been reported from maize in the country [6,8]. Although many investigations were conducted on hundreds of maize plants from different regions of Turkey, all were unsuccessful in detecting any presence of phytoplasma on this crop (Çaglar B.K., personal communication).…”