Resistance to<i>Fusarium oxysporum</i>f. sp.<i>luffae</i>in<i>Luffa</i>Germplasm Despite Hypocotyl Colonization

Abstract

Fusarium wilt of <i>Luffa</i>, caused by <i>Fusarium oxysporum</i> f. sp. <i>luffae</i>, causes great losses in <i>Luffa</i> plants worldwide. In this study, 45 accessions of <i>Luffa</i> germplasm were used to determine their resistance to <i>F. oxysporum</i> f. sp. <i>luffae</i> 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 <i>Luffa acutangula</i> and five of <i>L. aegyptiaca</i> 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 <i>L. acutangula</i> and one accession of <i>L. aegyptiaca</i> were resistant to Fol114. Seven accessions of <i>L. acutangula</i> and one accession of <i>L. aegyptiaca</i> were resistant to Fomh16. Despite the lack of any symptoms, the <i>F. oxysporum</i> f. sp. <i>luffae</i> isolates were recovered from the hypocotyls of all resistant accessions at 28 days postinoculation, 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 soilborne diseases in different cucurbit crops and further investigating the mechanisms of resistance to <i>F. oxysporum</i> f. sp. <i>luffae</i> in <i>Luffa</i> plants.