Resistance to Cowpea aphid-borne mosaic virus in in vitro germinated genotypes of Passiflora setacea

Abstract

Passion fruit (Passiflora edulis) is a fruit species of great relevance for Brazilian economy. However, it is highly susceptible to the Cowpea aphid-borne mosaic virus (CABMV). The species P.setacea, on the other hand, is resistant to the disease. The present study aimed to identify CABMV-resistant P. setacea genotypes for the introgression of genes into sour passion fruit genetic breeding programs. The seeds of passion fruit genotypes were germinated in vitro in MS culture medium. The seedlings were acclimatized in a growth chamber at the temperature of 27 ± 2ºC, photoperiod of 16:8 hours and 80% of relative humidity. Thirty plants of each genotype were mechanically inoculated with extract prepared from leaves collected from passion fruit plants with symptoms of CABMV for the assessment of resistance to CABMV. The severity of leaf symptoms was evaluated by means of a grading scale of visual signs. After the visual evaluation and identification of the asymptomatic genotypes of P. setacea, the PTA-ELISA test was carried out for 30 selected genotypes. According to the visual evaluation, all P. setacea genotypes were highly resistant to CABMV, while the P. edulis genotypes were highly susceptible. Out of the 30 genotypes selected, only PsRJ 4 was considered susceptible by PTA-ELISA. The other genotypes of P. setacea were considered resistant and present great potential for use in passion fruit genetic breeding programs.

Backcrosses in a segregating population of Passiflora mediated by morphoagronomic and resistance traits

“…This is due to the fact that group III contains the genotypes of the recurrent parent (P. edulis), known for being highly susceptible to CABMV. Passiflora setacea, in turn, allocated from group I, has a higher level of resistance to CABMV, which can be seen in other studies developed by our research group (Santos et al 2015 b;Freitas et al 2015;Santos et al 2017). The AUDPC is used to evaluate the severity of the woodiness virus, and it has shown to be efficient in identifying susceptible genotypes with levels of resistance to the virus in other works involving passion fruit (Santos et al 2015 b), P. setacea, and segregating populations (Santos et al 2015 b;Freitas et al 2015).…”

“…The periods of harvest, evaluation of fruits, and evaluation of the vegetative and floral morphological traits occurred throughout the entire year of 2016 until the first quarter of 2017. P. edulis (susceptible to CABMV) x P. setacea (resistant) Proteomic Interspecific Hybrids Phenotyping Estimates od genetic parameters Freitas et al, 2016) Evaluation of resistance to CABMV Freitas et al, 2015) Best-performing hybrids H5-14; H5-1; H2-10; H1-15L H5-16 H5-13 (donors)…”

Cowpea aphid-borne mosaic virus (CABMV) in Passiflora by qPCR analysis reveals asymptomatic plants with viruses and new species with immunity

“…With this in mind, genotypes that presented mild symptoms (DI from 4.19 to 15.75%) should be considered for selection aiming resistance to CABMV from interspeci c hybridization. Previous studies reported resistance to CABMV in genotypes belonging to P. setacea [22,48], P. cincinnata [22,24], P. gibertii [24] and immunity in P. suberosa [21]. This research is pioneer in reporting immunity to CABMV in P. bahiensis and P. pohlii and moderately resistant in P. miersii, amplifying the number of wild species of Passi ora spp.…”

“…Subsequently linear regression calculation was applied regarding the Cycle threshold variables (Ct) vs. Log of cDNA concentrations (ng.µL -1 ) to determine the correlation coe cient (R 2 ) among the points of each dilution and the curve inclination (Slope) [39]. The concentration of the number of copies of CABMV (copies.μL -1) in each point of the serial dilution was determined with application of the following formula: Copy Numbers (CN.µL -1 ) = (Sample concentration [ng] x 6.022x10 23 )/(fragment size [pb] x 1x10 9 x g/mol) [ 40 41].…”

“…However, so far there are no yellow passion fruit cultivars (P. edulis Sims) with this attribute [18][19][20]. On the other hand, several studies indicate that wild passion tree species carry CABMV resistance genes [21][22][23][24], and it is an alternative to develop resistant cultivars [18,25].…”