Ty-2 and Ty-3a Conferred Resistance are Insufficient Against Tomato Yellow Leaf Curl Kanchanaburi Virus from Southeast Asia in Single or Mixed Infections of Tomato

Abstract

Tomato yellow leaf curl virus (TYLCV), a monopartite begomovirus that originated in the Eastern Mediterranean, has spread worldwide, becoming a serious threat to tomato (Solanum lycopersicum L.) production. Southeast Asia is considered one of the hotspots for begomovirus diversity, and a wide variety of local begomovirus species distinct from TYLCV have been identified. In this study, the protection effect of introgressions of single TYLCV Ty resistance genes, Ty-2 and Ty-3a, in tomato was examined against inoculations of the bipartite begomoviruses Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) and Pepper yellow leaf curl Indonesia virus (PepYLCIV) isolated from Indonesia. Our findings suggest that Ty-2 in the heterozygous state was found to be ineffective against PepYLCIV and TYLCKaV, whereas Ty-3a in the heterozygous state was effective against PepYLCIV and partially effective against TYLCKaV. Quantification of viral DNAs showed correlation between symptom expression and viral DNA accumulation. Moreover, mixed infections of TYLCKaV and PepYLCIV caused notably severe symptoms in tomato plants harboring Ty-3a. In cases of mixed infection, quantifying viral DNAs showed a relatively high accumulation of PepYLCIV, indicating that Ty-3a loses its effectiveness against PepYLCIV when TYLCKaV is also present. This study demonstrates the lack of effectiveness of Ty resistance genes against single and mixed infections of distinct local begomoviruses from Southeast Asia.

A recessive gene pepy-1 encoding Pelota confers resistance to begomovirus isolates of PepYLCIV and PepYLCAV in Capsicum annuum

“…The effectiveness of Ty gene-mediated resistance against different begomoviruses is well studied in tomato. The Ty-3a gene is fully effective against PepYLCIV but only partially effective against TYLCKaV (Koeda et al, 2020). Additionally, Ty-2-conferred resistance is effective only against some monopartite begomoviruses, such as TYLCV-IL, but not against TYLCV-Mld and other monopartite or bipartite begomoviruses (Hanson et al 2000;Barbieri et al 2010;Tsai et al 2011;Shahid et al 2013;Prasanna et al 2015;Ohnishi et al 2016;Yamaguchi et al 2018).…”

“…The PepYLCIV and PepYLCAV DNAs were quanti ed using the CFX Connect Real-Time PCR Detection System (Bio-Rad, Hercules, CA, USA), as described previously (Koeda et al 2020), with a minor modi cation. The DNA A components of PepYLCIV and PepYLCAV were detected by quantitative PCR (qPCR) using IV-AV Real F and R primers, which ampli ed 102-bp fragments.…”

Lisianthus enation leaf curl virus, a newly invaded begomovirus into Japan, is more virulent than the prevalent tomato yellow leaf curl virus in Ty-gene-mediated resistant tomato cultivars

“…The LELCV SP Real F and R primers, TYLCV-IL SP Real F and TYLCV-IL-Mld Real R primers, and TYLCV-Mld SP Real F and TYLCV-IL-Mld Real R primers listed in Supplementary Table S1 were used to detect LELCV, TYLCV-IL, and TYLCV-Mld, respectively. The 25S ribosomal RNA gene of tomato genome DNA was ampli ed using 25S-rRNA 2F and 2R (Koeda et al 2020) for data normalization. Statistical analysis was performed using the Tukey-Kramer test of Excel Toukei ver.…”

“…The ampli ed PCR products were subjected to electrophoresis using a 1.0 % (w/v) agarose gel. The presence of Ty-2 and Ty-3/Ty-3a resistance genes in the collected tomato plants was con rmed using molecular markers following the method reported by Koeda et al (2020).…”

“…Momotaro is one of the most popular fresh market tomato cultivars in Japan, and MS and MP share a Momotaro genetic background (Koeda et al 2020). All plants were kept in a growth room at a temperature range of 23°C-30°C with 13 h photoperiods.…”