Hirano, Robert T., 1939-

Ito, P. J. (Philip J.), 1932-

Nakasone, Henry Y.

ScholarSpace at University of Hawai'i at Manoa

TECHNICAL PROGRESS REPORT NO. 161I~ INOVEMBER 1967PRELIMINARY OBSERVATIONS ON THE INHERITANCE OFSEVERAL FACTORS IN THE PASSION FRUIT(PASS/FLORA EDULIS L AND FORMA FLA V/CARPA)H. Y. NAKASONE, R. HIRANO, and P. ITOHAWAII AGRICULTURAL EXPERIMENT STATION, UNIVERSITY OF HAWAIITECHNICAL PROGRESS REPORT NO. 161 NO VEMBER 1967HAWAII AGRICULTURAL EXPERIMENT STATIONCOLLEGE OF TROPICAL AGRICULTUREUNIVERSITY OF HAWAIIIlon olulu, HawaiiPRELIMINARY OBSERVATIONS ON THE INHERITANCE OFSEVERAL FACTORS IN THE PASSION FRUIT(PASS/FLORA EDULIS L. AND FORMA FLAV/CARPA)H. Y. Nakasone, R. Hirano and P. lto "In most areas of th e tropical and subtropical world where passion fruit isgrown, the species Passiflora edulis (purple passion fruit) and its botanical form ,P. edulis, f. j1avicarpa (ycllow passion fruit) predominate. P. edulis, hereafterreferred to as edulis, is by far th e mor e popular in Australia, New Zealand,Brazil, and South Africa, while P. edulis f. j1avicarpa, hereafter referr ed to asflavicarp a, dominates commercial plantings in Hawaii.Although the passion fruit has been in cultivation for abo ut 50 years inHawaii and lon ger in other areas, reports of genetic studies arc meager. Severalreports (2, 3, 5, 6) from Australia and New Zealand indicate that edulis is suscep-tible and flavicarpa is resistant to a passion fruit wilt disease caused by aFusarium sp. Kajewski (4) reported that P. incarnate; a yellow-fru ited species,is also resistant to thi s wilt disease. Grozzmann and l'urss (;3) have gro wn F3 andbackcross (to P. edulis) progenies to select resistant types with edulis characte r-istics but have not reported its mod e of inheritance. Reports on inh eritance ofother factors are rare.A preliminary investigati on on the inheritance of a few charac te rs was madeon a small planting compose d of edulis, flaviearpa, F J , F2 and a backcro ss(t o flavicarp a) popul ati on on the Manoa campus and at the Waimanal o Experi-mental Farm. A deterr ent to genetic studies of passion fruit is th e high cost o festablishing a large number of individual " tree" trellises. Each vine must berestri ct ed to its own trellis in order to be identified easily. 'flit; studies reportedhere used such an individual " tree " trellis to maintain th e identity of each vine.Dr. H. Y. Nakasone is Asso ciate Horticulturist , R. Hirano is Assistant in Hesear ch , andDr . P. Ito is Assistant Horticulturist , at th c Hawaii ' Agricultural Exp eriment Sta tio n.3RESULTS AND DISCUSSIONCrown Rot and Wilt of Passion Fruit*The absenc e of edulis in commercial passion fru it plantings in Hawaii may bethe primary reason why a disease condition which results in crown rot and wiltin gof the vines has never been reported. The appearance of this uniden tifi ed diseasein an experimental planting provided th e opportunity to study the inheritance ofthe factors associated with this disease.Approximately a year and a half after field transplanting, edulis vines beganto wilt, and within six mon ths 30 out of 32 vines were dead . The two remainingvines were partially affected. Entire branches of healthy green leaves began to wiltsudd enly and were compl etely dead within a week. Leaf drop occurred aft er theleaves had completely dried . The two vines that were still alive after the 30 vineshad died showed symptoms of crown rot.Figure 1 illustrates a row of healthy flavicarpa vines. Figure 2 shows anedulis vine showing the first symptoms of wilt while Figure 3 shows an entire rowof edulis which died earlier. Figure 4 shows a close-up of a dead vine.A close examinat ion of the affect ed vines showed tha t the base of the vinenear the soil level (frequently referred to as the collar or the crown) had partiallyor completely rotted away . Figure 5 shows all of the primary branch trunksseverely but not compl etely rotted, while Figure 6 shows the primary branchtrunks comp letely rotted. Whether thc crown rot is the primary cause of wilt or asecondary symptom caused by root rot has not been clearly established in Hawaii.Data on the mode of inheritance of th e factors for this disease are given inTabl e 1. Segregation in the F2 population indicat es a simple 3: 1 ratio with edulispossessing a homozygous pair of recessive genes for susceptibility. Flavicarpa isresistant to this disease and its dominance is reflected in the Fj and other rat ios.From thc commercial standpoint , this disease is not of great importance inHawaii becaus e plantings are mainly of flavicarpa . However, it is importantin a breeding program directed towards develop ing varietie s that incorporate thedesirable trai ts of flavicarpa and cdulis .*The terms "crown rot " and "wilt" are used here in a descript ive sense and do not identify aspecific disease.4Table 1. Classification of observed and expected ratios for the wilting diseaseClassificationNumber of Observed Expected (3 :1) AdjustedProgeny plants alive dead alive dead X2 PPI =P. edulis 32 2 30 0 32P2 = f. flavicarpa 23 23 0 23 0F1 hybrid 6 6 0 6 0F2 scgrcganIs 35 28 7 26.25 8.75 0.24 .65Backcross 10 P2 24 24 0 24 0Tendril ColorTendril co lor is not a particularl y significant trait bu t because of its possiblecorrelation with fru it color, data were taken and the results arc presented inTaLle 2.Table 2. Inheritance data for tendril colorClassificationNumber of Observed Expected (3:1) Adjusted Approx.Progeny plant s Green Purple Green Purple X 2 P. value1'1 Ilavicarpa 23 0 23 0 231'2 cdulis 25 25 0 25 0F I hybrid 6 0 6 0 6F2 segrcgan ts 32 9 23 8 24 .042 .116Backcross 10 PI 24 0 24 0 2450\Figure1.Rowofflavicarpavinesonindividual"tree"trellises.Noneshowedcrownrotorwilting.Figure2.Edulisvineshowingfirstsymptomsofwilt.Brancheswithhealthyleavesarejustbeginningtowilt.--1Figure3.Rowof"tree"trelliseswithdeadvinesofedulis.Thetwolivevinesarebeginningtoshowsomecrownrotandwilt.Figure4.Aclose-upofadeadedulisvine.Leavesdonotcompletelyshedforalongtime.Figures 5 and 6. Crown rot which precedes wilt is shown in Figure 5 where four primary bran chtrunks are not completely rotted. Vascular connec tion still exists since muchof the top is living. Figure 6 shows five bran ch trunks complete ly rotte d and severed.The purpl e tendril color of flavicarpa is found to be dominant over th e greentendril color of edulis. The tendr ils of all Fl plants are purpl e, and the purpl e andgreen tendrils of the F2 segregants show an observed ratio closely approximatingthe expected 3: 1 ratio with purpl e being dominant. This dominance is also reflectedin the backcross progeny, all th e plant s of which were purpl e-stemmed, as expected.Fruit Shell ColorThe fruit shell color of f1avicarpa is a distinct yellow, while that of edulis isa dark purpl e. The fruit shell color of F 1 is reddish-purpl e and occasionally, ayellow tinge is noti ceable in the background. The Fl shell also has a whit e speck-ling, more promin ent in the Fl than in the parental flavicarpa fruits. The whitespeckling on f1avicarpa fruit s is subdued by the yellow base color. The reddish-purpl e shell color of the Fl app ears to be an intermediate color .In th e F2 population three color typ es are recovered but some difficultyarises in distinguishing the intermediat e from th e parental edulis color type. Theintensity of the purpl e color is often affected by differing exposure of th e froits tosunlight. Scgregation data for shell color arc summarized in Table 3.Table 3. Segregation of fruit shell color factor disregarding the speckling factor inthe F2 and backcross progeniesClassificationNumber of Observed Expected Ad1 Appro x.Progeny plants Purple Inter. Yellow Purple Inter. Yellow X P. valuep1 flavicarpa 23 0 0 23 0 0 23P2 edulis 25 25 0 0 25 0 0F1 hyb rid 6 0 6 0 0 6 0F2 segreganIs 23 4 12 7 5.75 U.5 5.75 .37 .84Backcross to PI 24 0 13 11 0 12 12 .04 .899Observed data on th e fruit shell color of the F 2 segregants do not reveal aratio deviating significantly from th e exp ected 1:2: 1 ratio. Th e low chi-squarevalue supports this interpretation. Th e observed backcross ratio and its low chi-square value also conform to th e expec ted 1: 1 ratio.Another interpretation of th e three colors observed in the F 2 segregants maybe based on th e presence of two pair s of alleles with interaction to produce a9: 3:4 ratio. Th e chi-square value calculated for thi s ratio is 0.21. Howev er, withouta larger number of plants in th e F2 population , further critical analy sis of thi shypothesis seems unwarranted.SUMMARY AND CONCLUSIONSA passion fruit disease that becomes apparent first in crown rot and lat er inwiltin g of green healthy leaves and st ems has been noted. Th e causal agent isnot known. Edulis vines showed susceptibility and flavicarpa vines showed resist-ance to th e disease, with inheritance data from limited populations indi cating asimple dominant gene for resistan ce.Purple tendril color is dominant over green.Fruit shell color app ears to be controlled by a single pair of genes with nodominance. Three color types are recovered in the F2 .Correlation of tendril and fruit shell color has not been made apparen t, but are-examination of th ese factors in larger population s seems desirabl e.10LITERATURE CITED1. Cox, J. E. and T. B. Kiely. 1961. Fusarium resistant rootstocks for passion vines.Agric. Gaz., New South Wales; Vol. 72 (6): 314-318.2. Grozzmann, H. M. and G. S. Purss. 1958. Beatin g passion vine wilt. QueenslandAgric. Jour . Vol. 84 : 341-346.3. Kajewski, S. F. 1941. Cross breeding experiments in the Bowen Distri ct. Queens-land Agric. Jour. Vol. 56 (6) : 473 -476.4. McKnight, T. J951. A wilt disease of the passion vine (Passiflora edulis) causedby a species of Fusarium . Queensland Jour . Agric. Sci. Vol. 8 :1-4.5. Passion vine wilt and collar rot. 1960. Orchardist, New Zealand ; Vol. 33 (7) : 225.6. Purss, G. S. 1958 . Studies of the wilt resistance of species of Passiflora toFusarium wilt (F. oxysporium f. possiflora ei. Queensland Jour. Agric. Sci. Vol.15: 95-99.11UNIVERSITY OF HAWAIICOLLEGE OF TROPICAL AGR ICULTUREHAWAII AGRICULTURAL E X PE RI M E N T STATIONHONOLULU, HAWAIITHOMAS H. HAMI LTONPresident of the UniversityC. PEAl RS WI LSONDean of the College andDirector of the Experiment StationG. DONALD SHERMANAssociate Director of the Experiment Station

Preliminary observations on the inheritance of several factors in the passion fruit (Passiflora edulis L. and forma flavicarpa)

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Preliminary observations on the inheritance of several factors in the passion fruit (Passiflora edulis L. and forma flavicarpa)

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