In Vivo Transmission of ‘<I>Candidatus</I> Phytoplasma ulmi' by <I>Amplicephalus curtulus</I> (Hemiptera: Cicadellidae) and Its Effect on Ryegrass (<I>Lolium multiflorum</I> Cv. Tama)

Abstract

In Chile, phytoplasmas have been reported in sugar beet, grapevine, peony, and Chilean shrubs. 'Candidatus Phytoplasma ulmi' have been detected in plants of Ugni molinae Turczanínow (Myrtaceae) and the leafhopper Amplicephalus curtulus Linnavuori & DeLong. We evaluated the possibility of phytoplasma transmission from native plants to grasses by A. curtulus and the possible effect on the plant hosts. Newly emerged adults were placed in cages with phytoplasma-infected U. molinae for 72 h (acquisition access period). These plants were then replaced by healthy ryegrasses for 20 d (latent period). They were again replaced for other healthy ryegrasses and were place in cages for 14, 7, and 1 d (inoculation access period [IAP]). After IAP, these plants were moved into different insect-free cages for 30 d, after which polymerase chain reaction (PCR) analyses were carried out. Phytoplasma-free insects on ryegrasses were considered as control treatments. Furthermore, plant height and leaf area were recorded for all treatments. After PCR, 46, 60, and 13% of the plants exposed to infected A. curtulus by 14, 7, and 1 d of IAP, respectively, were infected with 'Ca. Phytoplasma ulmi'. Similarly, plants exposed to an IAP of 14, 7, and 1 d with phytoplasma-infected leafhoppers showed a reduction in plant height of 19, 39, and 28% and leaf area of 302, 169, and 55%, respectively, in comparison to those exposed to phytoplasma-free leafhoppers. We showed that A. curtulus has the ability to transmit phytoplasma from U. molinae to ryegrasses, affecting ryegrass plant height and leaf area

Infection of ‘Candidatus Phytoplasma ulmi’ reduces the protein content and alters the activity of detoxifying enzymes in Amplicephalus curtulus

“…In this period, it was between 330 and 420 CPu GU ng À1 of insect DNA. In similar conditions, we previously demonstrated that A. curtulus suitably transmitted phytoplasma from 35 to 41 days after AAP (Arismendi et al, 2014), which supports the results presented here. Similar or lower values have been previously detected by quantitative PCR (Marzach ı & Bosco, 2005;Galetto et al, 2009).…”

“…Considering that the lowest value on the calibration curve was 8 fg in 1 ng of insect DNA (610 CPu GU ng À1 of insect DNA), real-time PCR values obtained in this period represent almost half of the minimum value used in the calibration curve. We showed that females have a high phytoplasma titer in their head-thorax section, higher than the minimum considered to allow transmission (Galetto et al, 2009), indicating that the period 35-45 days post-AAP could be considered a suitable transmission period (Arismendi et al, 2014). In this period, the phytoplasma may still be circulative, but not totally propagative.…”

“…would not be able to detect this pathogen because of its low levels. Phytoplasma ulmi' infections, as metabolic pathways were activated to deter the phytoplasma invasion, despite this species' ability to transmit the phytoplasma (Arismendi et al, 2014). Thirty-five days after the AAP, the phytoplasma titer showed an increase (15 300 CPu GU ng À1 of insect DNA) in the abdomen of females.…”

“…Tama) and possibly other plant species in Chile (Arismendi et al, 2011b(Arismendi et al, , 2014Longone et al, 2011). Phytoplasma ulmi' in ryegrass (Lolium multiflorum Lamarck, cv.…”

The underestimated diversity of phytoplasmas in Latin America

“…Such differential distribution of phytoplasmas is probably due to the diversity and preferential distribution of their insect vectors. While some leafhopper vectors of phytoplasma, such as species of Dalbulus, have been detected in all Latin American countries (Nault, 1980(Nault, , 1983, others, such as Amplicephalus curtulus, have been detected only in Chile and Colombia (Alvarez et al, 2009;Arismendi et al, 2014).…”