Characterization 3333 of tomato (Solanum lycopersicum) accessions for resistance to phylotype I and phylotype II strains of the Ralstonia solanacearum species complex under high temperatures

Abstract

Bacterial wilt of tomato caused by Ralstonia solanacearum species complex (RSSC) causes substantial yield losses in the tropics and subtropics. Disease management options by chemicals are limited, and host resistance is the cheapest and easiest means of control. However, sources of bacterial wilt resistance in tomato are limited.The disease often coincides with higher temperatures in the tropics, and resistance sources that are more heat stable are particularly valuable for breeding of tropically adapted tomato cultivars. The objectives of this study were to identify tomato accessions that demonstrate relatively high bacterial wilt resistance under high temperatures and to identify accessions that may possess QTLs other than Bwr-6 and Bwr-12 (two major disease resistance QTLs against bacterial wilt), which could be exploited in future breeding. Sixty-seven tomato entries reported as bacterial wilt resistant were evaluated in a greenhouse against one strain each of phylotype I (Pss4) and phylotype IIB (Pss1632) of the RSSC (average temperature ≥29°C). Of those, five and 19 were homozygous for Bwr-6 and Bwr-12, respectively, and six were homozygous for both QTLs. Bwr-12 contributed to resistance against phylotype I strain but not against the phylotype II strain. Bwr-6 contributed to resistance against both phylotype strains. Entries with both QTLs as a group performed relatively better against the phylotype I strain. Entry "94T765-24-79", which lacked Bwr-6 and Bwr-12, demonstrated relatively high resistance against the phylotype II strain and may carry new QTL/s. As new bacterial wilt resistance QTLs are mapped and markers designed, pyramiding multiple bacterial wilt resistance QTLs into new varieties should be straightforward, thereby increasing the chances of obtaining stable resistance. K E Y W O R D S bacterial wilt, Bwr-12, Bwr-6, marker-assisted breeding, Ralstonia solanacearum species complex, Solanum lycopersicum

Whole genome resequencing and complementation tests reveal candidate loci contributing to bacterial wilt (Ralstonia sp.) resistance in tomato

“…The accession F 7 80-465-10-pink was the most resistant to Pss1632 (92.5%), while TBL-2 was the most susceptible (100% of symptomatic plants) (Table 1). The resistant and susceptible reactions of the accessions screened in this study were generally in alignment with the previous work of Kunwar et al 12 employing a partly overlapping set of materials. Hai et al 17 reported that LA3501 was resistant to BW strain Pss186 but susceptible to Pss4.…”

“…These results support the extensive body of literature highlighting the complexity of host-pathogen interactions in the tomato-BW pathosystem, as reviewed by Hayward et al 3 . Furthermore, the higher level of virulence of Pss1632 was previously reported 12 . When challenged with Pss4, LS-89 and F7 80 Pink were the most resistant accessions (100% resistant), while Pant Bahar, L390, and LA3501 were the most susceptible (0%) (Table 1).…”

“…None of the lines had complete resistance to both pathogen strains (Pss4 and Pss1632) in these trials, including H7996, the best-known tomato resistance source (Table 1). Wilting can occur in BW resistant tomato lines, the extent of which depends on pathogen strain, temperature, and other environmental conditions 12,17,18 . However, the proportion of wilted plants in resistant lines was usually less than in susceptible lines (Table 1).…”

Evaluation of Biocontrol Agents Against Bacterial Wilt in Tomato Using Seedling Screening

“…Wilting percent on L390 was higher than on the moderately resistant cultivar L180 treated with biocontrol. This is not unexpected since the cultivars differ in reaction to infection by R. pseudosolanacearum where L390 is highly susceptible, and L180 is moderately resistant with wilting percent ranging from 90-100% and 40-60%, respectively [15,19,20]. This study found that wilting percent reduced up to 50% for L390 and 10% for L180 when BCA was applied to seedlings (Table 1), indicating that the combination of resistance and BCA can better control BW than either alone.…”

Identification of Bacterial Wilt (Ralstonia Solanacearum) Resist Ance in Cherry Tomato

“…cerasiforme (Hanson et al, 1998). Breeding bacterial wilt-resistant tomato varieties is difficult because resistance is often dependent on pathogen strain, which is highly affected by environmental conditions such as soil type, temperature, pH and moisture (Wang et al, 1998;Prior et al, 2016;Kunwar et al, 2019).…”