Passion fruit work in Uganda

M O Ssemakula1, V Aritua2, R Edema1, T Sengooba3,

J J Hakiza2, J Tumwine2, S Kyamanywa1 & E Adipala4.

1Department of Crop Science, Makerere University, Uganda.2NaCRRI, National Agricultural Research Organization, Uganda.

3IFPRI, Kampala, Uganda.4RUFORUM, Kampala, Uganda.

Background

The crop: Passion fruit• Is a major export crop from Uganda to the

European market.

• Is mainly grown by small-scale farmers in the Eastern and Western highlands of Uganda.

• Was cultivated on a large-scale in Central Uganda between 1990-2000 as part of the export diversification initiative of the Ugandan Government.

• Earned Uganda US$ 100,000 from the export of 50metric tons at the peak of production in 1998.

Background

The problem: Reduced productivity

• Since 2000, fluctuations in production and export have been realized.

• By 2005, only 7tons of fresh fruit were being exported from Uganda.

• Reduction in production has been attributed to biotic and management-related factors first identified in feasibility and market-oriented studies from 1989-1993.

Background

Limiting factors to production & export:

• Pests and diseases.

• Limited commercial germplasm pool:• Dominated by a single variety, the Kawanda Hybrid.

• Kawanda Hybrid is susceptible to prevalent pests and diseases.

• Poor agronomic and post harvest practices, thus:• Variability in the quality of produce.

• Fruit damage.

Background

Diseases:

• Are the most significant biotic constraint to passion fruit production in Uganda.

• Priority diseases include:• Brown spot.

• Collar rot.

• Viral diseases.

Background

Management of priority diseases:

• Brown spot:• Mainly occurs in warm, humid production

areas.

• Is currently being managed using the fungicide Ridomil (Dithane M45), which controls disease incidence and severity (Ssonko et al. 2005).

Background

Management of priority diseases:

• Collar rot:• Introduction of improved germplasm from external

sources (Campbell 1992, NARO 1994).

• Grafting of Kawanda Hybrid to tolerant local yellow rootstock (Ssekyewa 1993, NARO 1998, ADC/IDEA 1999).

• Screening of local yellow and sweet calabash (hard-shelled) passion fruit types for disease tolerance, with some success in screen house trials (NARO, 2006).

Background

Management of priority diseases:• Viruses:

• Retrieval of Kawanda Hybrid clones 5, 6, 7 and 8, previously lost from the Horticultural Program (NARO 1994, ADC/IDEA 1999).

• Dissemination of clean planting material to farmers (MAAIF 1990, NARO 2000, ADC/IDEA 2000, 2002).

• Identification of the causal agent as a potyvirus similar to passion fruit woodiness virus (PWV) and cowpea aphid-borne mosaic virus (CABMV).

Background for IPM CRSP Work

Impact of management efforts for viral diseases was not felt because:• Data on disease epidemiology was not

adequate enough for appropriate management strategies to be formulated.

• Causal agents were not fully identified while widespread variation in disease distribution was suggestive of multiple species or strain occurrence.

• No sources of tolerance were identified to counteract the susceptibility of commercial germplasm.

Background

Viral diseases on passion fruit, therefore escalated since the cultural measures in use were ineffective in disease management.

A research program on passion fruit viruses was then initiated at Makerere University to:• Map viral disease incidence and severity.

• Identify and characterize viral pathogens.

• Characterize and screen local passion fruit germplasm for sources of host tolerance to viruses.

Disease mapping

Two disease surveys were conducted in 15 major passion fruit-growing districts of Uganda during November 2003 and May 2005.

Data on disease incidence and severity were collected and mapped using Geographical Information System (GIS) software (Ilwis 3.1 and ArcView 3.2).

Map to show incidence of viral diseases on passion fruit in

Uganda

D.R.C KENYA

SUDAN

TANZANIARWANDA

Lake Victoria

2

1

3 4

5

6

7

8

9

10

11 12

13

15

14

0 200 Kilometers

N

EW

S

250000

250000

500000

500000

750000

750000

0 0

250000 250000

Incidence scale

4 - 1516 - 2728 - 3839 - 5051 - 6162 - 73

Kabarole (1)

Kasese (2)

Bushenyi (3)

Mbarara (4)

Mubende (5)

Mpigi (6)

Masaka (7)

Apac (8)

Nakasongola (9)

Luwero (10)

Wakiso (11)

Mukono (12)

Iganga (13)

Mbale (14)

Sironko (15)

Pathogen identification

The Ugandan Passiflora potyvirus has been identified:• As a novel potyvirus species on passion fruit:

• With AA motifs associated with aphid-transmission.

• With biological similarity to CABMV, passion fruit ringspot virus and PWV

• Distinct from PWV, CABMV and other viruses causing passion fruit woodiness disease worldwide such as Cucumber mosaic virus and East Asian Passiflora virus.

Alignment of partial virus coat protein for the Uganda Passiflora

potyvirus against known potyviruses and other viruses on

passion fruit worldwide UGM-19 1 S--GK----- KDEEIDAGKD ---KEKSKEQ KNTEQPG--- -RV------- --TSTPPTSIUGM-58 1 S--GK----- KDEEIDAGKD ---KEKSKEQ KNTEQPG--- -RV------- --TSTPPTSIUGM-73 1 S--GK----- KDEEIDAGKD ---KEKSKEQ KNTEQPG--- -RV------- --TSTPPTSIPV-0707 1 S--GK----- KDEEIDAGKD ---KEKSKEQ KSTEQPG--- -RV------- --TSTPPTSIUGM-17 1 S--GK----- KDEEIDAGKE ---KEKNKEQ RSVERTE--- -KL------- --TLSSAANTBCMV-Y 1 S--GT--GQP QPPIVDAGVD ---AGKDKRE RSNRGKD--- -PEGREGSGN NNRGAGDSTMTCY-8648 1 S--GT----G VVEGIDAGVD ---SRKKKQV EESSKNV--- -AE------- ----PEIIDHPWV-CL1 1 S--GSMSGKD KDETLDAGGD ----GK---- RSTGKKA--- -AEG--SGGD SRKKSEEDTTPWV-6715 1 S--GSMSGKD KDETLDAGGD GKRSTGKKTA EGSGGDS--- -RK------- ---KSEEDTTPWV-M3 1 SDG------- KDKELDAGKD ---KEKDKEA KEQSVQQ--- -KQ------- --AKNKGAKECABMV-Z 1 SDE------- RQKELDAGKD ---KDKAKEA REQSTQQ--- -KQ------- --AKNKGAKECABMV-Ib 1 SGR------- RQEELDAGQD ---KDKGKEG TEQSTQQ--- -K-------- --TKKKGINECAB-SAPV 1 SGR------- KQEELDAGKD ---KEKTKEG EEQSTQQ--- -KQ------- --TKDKGTKEEAPV-AO 1 TKSEENKDEL GKDAIDAGND GKRKDKEKE- --GMVTP--- -PTNPNPNNS KFG-GSSFNREAPV-IB 1 SSTGKDKEEE SKDTIDAGGD GGRKDKEKEK RTGTLAT--- -LENPNPINP NGGDGSSLGRPVY-2567 1 MA-------- -NDTIDAVES NKKESKPEQG SIQSNSN--- -KG------- ----------PLV-0082 1 M-----PPKE APEVVPPPVP PPLPMKEKEA SSSSEPNDEE LRQRRLLKLI EILQAQNHNSMSV-A(Km) 1 MSTSKR---- -----KRGDD SNW----SKR VPKKK----- --------PS SAGLKRAGSKOFV-2444 1 MANPSEIDYM TPLSAYEGVP AEYQEATSSP TPKEYTRDAA KAIPICILPA PPGNEVEVAEOKMV-0352 1 M--------- ---------- ---------- ---------- ---------- ----------TYLC-0601 1 M--------- ---------- ---------- ---------- ---------- --------SKTORS-6765 1 W--------- ---------- ---------- ---------- ---------- ----------CMV-RT52 1 M--------D KSGSTSAGRN RRRRPRRGSR SAPSSADANF RVLSQQLSRL NKTLAAGRPTMARM-3569 1 M--------- ---------- ---------- ---------- ---------- ----------

Phylogeny of the Ugandan Passiflora virus

PWV-Au2

PWV-CL1

CABMV-Z

CABMV-SAP

PWV-M3*

CABMV-Ib

EAPV-AO

TCY-8648

BCMV-Y

UGM-17-3

UGM-19a-4

PV-0707

UGM-73-10

UGM-58-1

PVY-NTN

PVY-2567

TYLC-060

CMV-RT52

OKMV-035

MARM-356

TORS-676

OFV-2444

PLV-0082

MSV-A (Km)

100

75

100

32

27

90

98

9

23

17

9280

52

35

42

85

18

15

11

28

0.05

Passion fruit woodiness virus

Cowpea aphid-borne mosaic virus

East Asian Passiflora virus

Ugandan Passiflora virus

Representative isolates for other viruses reported on passion fruit worldwide

Genetic similarity analysis

Amino acid identity values (%) Species-isolate

UGM-17 UGM-19 UGM-58 UGM-73 PV-0707 UGM-17* - - - - - UGM-19* 88 - - - - UGM-58* 88 100 - - - UGM-73* 88 100 100 - - PV-0707* 87 98 98 98 - PVY-NTN* 56 56 56 56 56 BCMV-Y* 73 73 73 73 72 PWV-CL1* 71 71 71 71 70 PWV-6715* 61 62 62 62 61 CABMV-Z* 74 73 73 73 72 CABMV-Ib* 73 75 75 75 74 CABMV-SAP* 76 76 76 76 76 EAPV-AO* 72 73 73 73 72 PLV-0082 7 9 9 9 9 TYLCV-0601 3 2 2 2 6 CMV-RT52 3 1 1 1 7 OFV-2444 5 4 4 4 5 OkMV-0352 3 3 3 3 2 MarMV-3569 5 12 12 12 12 TORSV-6765 4 5 5 5 5

Virus characterization

Host assays using 26 plant species in Nicotiana, Chenopodium, Datura and Passiflora:• Revealed variability across virus isolates:

• Host range.

• Severity of infection.

Germplasm Characterization

Sixty accessions of 5 passion fruit types were collected from farmers’ fields.

Morphological characterization done in 2005B and 2006A:• High variability in phenotypic traits for

germplasm within and between locations.• Plants with beneficial qualitative and

quantitative traits were identified.

Morphological characterization of passion fruit in Uganda: Field

trial

Morphological characterization of passion fruit in Uganda: Screen

house trial

Molecular characterization

Simple sequence repeat (SSR) markers:• Not polymorphic enough across species.

Random amplified polymorphic DNA (RAPD) markers:• Currently under evaluation.

• Preliminary results reveal genetic diversity within and across species.

Germplasm screening for virus tolerance

Experiment: • Completely Randomized Design in a screen house

trial.

• Double graft technique for plant inoculation.

• Six accessions of yellow, hard-shelled and sweet granadilla types were grafted to 4 virus isolates maintained on passion fruit.

• Data collected from 30 days after second grafting, for a duration of 5 months.

• Data type: Disease severity and virus titre (ELISA).

Graft inoculation of passion fruit

ANOVA for tolerance of graft inoculated passion fruit seedlings

to viral infectionCHANGE DF SS* MS* VR* F. PR.

Virus titre 1 7.3 7.3 8.2 0.006

Week after Grafting (WAG)

6 68.1 11.4 12.7 <0.001

Virus isolate 3 13.2 4.4 4.9 0.004

Germplasm 5 28.2 5.6 6.3 <0.001

WAG X Isolate 16 31.1 1.9 2.2 0.018

WAG X Germplasm 24 25.2 1.1 1.2 0.309

Isolate x Germplasm 3 1.8 0.6 0.7 0.587

WAG X Isolate X Germplasm

7 6.6 0.9 1.1 0.408

Residual 52 46.6 0. 9

Total 117

228.1 1.9*Values were rounded off.

Summary of disease data for passion fruit germplasm

screening trial under screen house conditions in Uganda

Most tolerant:• Germplasm 3 & 4.• Not important

commercial types currently.

• Have potential for breeding purposes.

WAG Germplasm accession Mean severit

y1 2 3 4 5 6

4 1.06

1.02

1.01 1.04

1.03

1.01

1.02

6 3.62

5.05

2.32 - 4.50

4.54

3.34

8 2.74

3.99

1.82 - 3.97

3.22

2.46

10 1.92

3.03

1.55 1.01

0.94

3.91

2.25

11 2.64

3.99

2.85 0.99

- 3.60

3.03

14 3.97

2.96

2.29 1.96

- 3.63

2.83

16 3.69

2.99

1.96 - - 3.26

2.60

Mean 2.36

2.87

1.84

1.15

2.43

3.09

LSD (0.05)

1.7841.09

CV (%)

Partners

Funding:• Innovations at Makerere Program (Rockefeller Foundation/

World Bank).• International Foundation for Science.• Faculty of Agriculture (Sida-SAREC and NORAD grants).

Technical support/Collaboration:• Deutsche Sammlung von Mikroorganismen und Zellkulturen

(DSMZ), Germany.• National Agricultural Research Organization (NARO):

• National Crop Resources Research Institute (NaCCRI):• Horticultural Research Program (NHRP).

• National Agricultural Research Laboratories:• Agricultural Biotechnology Centre (NABC).