Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus

Abstract

Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of ACY were evaluated against those of Ty-3 linked marker P6-25 through screening of commercial resistant and susceptible tomato hybrids, and genetic segregation using F2 population derived from a commercial resistant hybrid AG208. With the use of bioinformatics and DNA sequencing analysis tools, deletion of 10 nucleotides was observed in Ty-3 gene sequence for susceptible tomato variety. ACY is a co-dominant indel-based marker that produced clear and strong polymorphic band patterns for resistant plant distinguishing it from its susceptible counterpart. The obtained result correlates with 3:1 segregation ratio of single resistant dominant gene inheritance, which depicted ACY as gene-tag functional marker. This marker is currently in use for screening 968 hybrids varieties and one thousand breeding lines of tomato varieties stocked in Jiangsu Green Port Modern Agriculture Development Company (Green Port). So far, ACY has been used to identify 56 hybrids and 51 breeding lines. These newly detected breeding lines were regarded as potential source of resistance for tomato breeding. This work exploited the sequence of Ty-3 and subsequently contributed to the development of molecular marker ACY to aid phenotypic selection. We thus recommend this marker to breeders, which is suitable for marker-assisted selection in tomato.

Validation of some disease-resistance molecular markers associated with multiple diseases in tomato for marker-assisted selection program

“…A total of 8 markers are exploited and among them, 6 (ACY, Ty1-3, P6-25, SCAR1, SCAR2, P1-16) were selected as efficient markers. Though marker P6-25 shows outstanding performance, it could generate recombination events during MAS as observed by Adedze et al [14] when comparing efficiency of ACY to P6-25. Hereof, ACY and Ty1-3 known as gene-based markers are more preferable and recommended to tract Ty1 and/or Ty3 in tomato.…”

“…Total DNA was extracted from the fresh leaves of 60-day old tomato breeding lines using NuClear Plant Genomic DNA Kit (CWO531M) protocol (CW-Biotech, Beijing, China) following Adedze et al [14]. The extracted DNA was adjusted to a final conwww.scienceasia.org centration of 50 ng/µl.…”

“…However, P6-25 could be specifically used to explore Ty3 resistance gene and its derivative alleles Ty3, Ty3a, and Ty3b. ACY and Ty1-3 are developed based on gene locus Solyc06g051170 and Solyc06g051190, respectively [14,15]. For Ty1 tracking, SCAR1 has emerged as a promising marker, while SCAR2 and P1-16 could be effectively used for Ty2 detection.…”

“…Not all developed markers have the same reproducibility, thus arguing the concept of several different marker development for a single gene. Adedze et al [14] has reported that it may not be advisable to depend solely on a single type of molecular marker for MAS because it may not always generate accurate band pattern under different experimental conditions. So far, some of the gene-linked markers could be easily improved as locus-specific marker following the cloning of their related R gene, except Ty2 that may require complex cloning technique.…”

The Role and Contribution of Plant Breeding and Plant Biotechnology to Sustainable Agriculture in Africa

“…MAB approaches have been used for several traits including: the development of abiotic stress tolerance (aluminum and manganese-tolerant crops which can grow in acidic soils, water-inundated soils, salt tolerance, drought tolerance); the development of biotic stress (e.g. bacterial, viral and fungal disease resistance, and insect resistance (Nevame et al 2018: ); improving agronomic traits (e.g. yield); generation of higher nutrient levels (e.g.…”