Resistance toFusarium oxysporumf. sp.luffaeinLuffaGermplasm Despite Hypocotyl Colonization

Abstract

Fusarium wilt of Luffa, caused by Fusarium oxysporum f. sp. luffae (Folu), causes great losses in Luffa plants worldwide. In this study, 45 accessions of Luffa germplasm were used to determine their resistance to Folu isolates (FOLUST, FOLUSC, Fomh16, and Fol114) in two independent trials. In the first trial, only FOLUST was used to preliminarily identify resistant accessions. Nine accessions of L. acutangular and five of L. aegyptiaca were resistant to the FOLUST isolate. In the second trial, the other three isolates were then used to reevaluate the 14 resistant accessions. The results indicated that the 14 accessions were resistant to FOLUSC but exhibited variable resistance to the Fomh16 and Fol114 isolates. Eight accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fol114. Seven accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fomh16. Despite the lack of any symptoms, the Folu isolates were recovered from the hypocotyls of all resistant accessions at 28 days post inoculation, except for isolates FOLUSC and FOLUST on one accession (LA140). A high percentage (87.5%) of accessions collected from Bangladesh were identified as resistant, highlighting the effect of local adaptation on resistance. These results provide potentially valuable genetic resources for breeding programs to develop new varieties or rootstocks that could be beneficial for controlling soil-borne diseases in different cucurbit crops and further investigating the mechanisms of resistance to Folu in Luffa plants.

Analyzing genetic diversity in luffa and developing a Fusarium wilt-susceptible linked SNP marker through a single plant genome-wide association (sp-GWAS) study

“…This finding aligns with previous research indicating significant variations in luffa’s resistance to Fusarium wilt across different countries. For instance, there were no instances of Fusarium wilt-resistant luffa in Cambodia and Uzbekistan [ 38 ].…”

“…However, luffa production faces substantial losses due to luffa Fusarium wilt, a severe disease caused by the fungus Fusarium oxysporum (Fo). This resilient fungus can persist in the soil for an extended period, and infected plants display symptoms such as slow growth, yellowing of lower leaf, and browning of vascular bundles, ultimately leading to reduced yield and plant fatalities [ 13 ]. While several control methods are currently available, many of them are unsuitable due to cost, effectiveness, and environmental concerns.…”

Reaction of Luffa spp. to Macrophomina pseudophaseolina inoculation

“…Hilal et al (2000) tested fungi isolated from the roots and seeds of Luffa aegyptiaca Mill and found that M. phaseolina was not pathogenic to this crop. Subsequent studies also highlighted the resistance of this cucurbitaceous plant when inoculated with other root pathogens (Bruton et al, 2000;Kwon et al, 2001;Namisy et al, 2023;Bindal et al, 2023).…”

Histopathology and quantification of green fluorescent protein-tagged Fusarium oxysporum f. sp. luffae isolate in resistant and susceptible Luffa germplasm

“…Cultivars with resistance are the most effective defense against soil-borne diseases. Fusarium wilt-resistant cultivars have been reported in L. acutangula and L. aegyptiaca ( 16 ). However, the resistance mechanism against Folu in the Luffa species is largely unknown.…”

“…More research studies have indicated that Fon could penetrate and colonize the roots of the highly resistant watermelon line but failed to enter the vascular system ( 23 ) and did not result in wilt symptoms ( 24 ). A previous study reported that four Folu isolates colonized the hypocotyl of highly resistant Luffa accessions without displaying symptoms ( 16 ). This behavior might be similar to Fon in that Folu colonizes hypocotyl in the resistant Luffa but does not move into the vascular system.…”