The 29th International Horticultural Congress | Sustaining Lives, Livelihoods and Landscapes | 17-22 August 2014
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Welcome to the 4th International Papaya Symposium

Sponsored by the ISHS Section Tropical & Subtropical Fruits and the Working Group Papaya

The IV International Symposium on Papaya will be convened in the Tropical Horticulture Theme during the International Horticultural Congress 17-22 August (IHC2014) in Brisbane, Australia.

Papaya is one of the major tropical fruit crops worldwide where it is grown widely both as a commercial crop and in backyards where it is an important source of nutrition and income. There has been a comprehensive research effort in papaya which is a model for research in other tropical fruit species. Breeding programmes in many countries and the development of a wide range of molecular markers are leading to new varieties and application of marker assisted breeding. The diseases and insects affecting papaya include papaya ringspot virus and other emerging diseases are the major factors limiting papaya production. The papaya genome was sequenced in Hawaii and that has led to rapid progress in genomics, molecular markers and identification of genes and their function in both papaya and related Vasconcellea species. Recent advances in these and other related topics will be discussed at the symposium.

We invite everyone involved in papaya research, education and extension, trade and commercial production to come, present your research and join us in this important symposium.

Oral and poster papers are invited on the following themes:

  • Papaya Production and Cultural Practices
  • Papaya Breeding
  • Current Status of Papaya Diseases and Control
  • Genomics and Biotechnology
  • Postharvest and Product Development


Dr. Maureen Fitch is based at the Hawaii Agriculture Research Center, USA. Maureen is a plant physiologist and is well known for her research and publications on papaya. She pioneered research on the development of transgenic papaya, resistant to Papaya Ringspot Virus. Her subsequent breeding program led to the first commercial transgenic fruit crop. Her current research includes micropropagation of transgenic papaya, and transformation and characterisation of anthuriums.

Dr. Yun Judy Zhu is based at the Hawaii Agriculture Research Center, USA. Judy’s research mainly focuses on the biochemical and molecular mechanism of plant responses to microbes. Papaya’s host resistance mechanisms are being studied through comparison of genomic sequences and protein expression profiles and molecular identification of genetic markers associated with host resistance.

Dr Rod Drew is a Professor at Griffith University, Brisbane. Rod has been an active researcher of papaya and active member of ISHS since the 1970s. His research in papaya has covered micropropagation, cryopreservation, embryo rescue and plantlet recovery, traditional breeding, marker assisted breeding, intergeneric hybridisation between papaya and related Vasconcellea species, development of molecular markers and identification of genes that control PRSV-P resistance in Vasconcellea species.

Keynote Speaker

Dr Aart Louw currently leads a papaya breeding programme for Neofresh, Hectorspruit, South Africa. Neofresh is a major papaya producing company in South Africa. Aart imported genetic material from Brazil and established new F1-hybrids suited for their specific needs locally. He completed graduate and postgraduate studies at the University of Pretoria and was awarded a DSc (genetics) in October 1981. He was initially involved in tomato breeding, produced a tomato cultivar, Rodate, with a high degree of resistance to bacterial wilt. He was a tomato breeder in the service of the then, “Department of Agriculture and Technical services”; was a lecturer at University of Pretoria; and, worked for Langeberg, a canning company, as a researcher. His priority was tomatoes but he was responsible for technical advice on most of the crops grown by the company. H later did research on tobacco with emphasis on breeding and seeking solutions for bacterial wilt, also called Granville wilt. In 1990 he became director of the research station and in 1992 became a consultant for the Agricultural Research Council (Institute for Tropical and Subtropical Crops) that is ARC (ITSC) on their breeding programs. One of the breeding programs was on papaya and Aart initiated a papaya breeding program in 1993. The consultancy with ARC ended in 2009 resulting in a number of pure lines (seed and protocol) for the synthesis of a number of papaya F1-hybrids. During the period from 1992 to present, in addition to consultation to the ARC, he consulted to a number of papaya producers regarding papaya production practices and also as a director to a company to initiate commercial agriculture in Gabon. He has been working for Neofruit since 2009.

Aart Louw will present a keynote address on: Papaya Breeding – a Conventional Approach

The aim of the presentation is to highlight some practical considerations in a papaya breeding program.

Papaya, as an object to breeding, has a few peculiarities that have to be accountant for. It is neither a typical tree crop nor a typical annual crop. As an example, most tropical and subtropical tree crops such as litchi, avocado and mango have generation time spanning a couple of years in contrast with papaya that is less than 18 months. On the other hand, annual crops have a characteristic generation time of less than six months. These peculiarities are also true for number of trees (plants) per unit area and productive life span of an orchard. There is however at least one similarity between papaya and annual crops and that is the ease with which one can make controlled pollinations and even more important the number of progeny from each pollination attempt. These peculiarities have a profound effect on the profitability and expense of a conventional papaya breeding program.

There are beautiful and elegant mathematical plant breeding models available. It is however necessary to evaluate the feasibility of this in a papaya breeding program.

Address the following:

  • Strategic considerations
    • Costs and returns
    • Seed versus vegetative production
    • Maintaining breeding lines
    • Seed production
  • Some genetic considerations
    • Effects and consequences of inbreeding
    • °Brix
    • Sexuality
    • Freckle spot
    • Length of internodes
    • A number of specific characteristics, advantageous and problems

There is room for papaya breeders to apply papaya breeding to solve questions of fundamental genetics as well as, breeders dedicated to supply the industry with improved cultivars.

Dr Cameron Peace is an Associate Professor in tree fruit genetics in the Department of Horticulture at Washington State University, USA. He is project co-director of "RosBREED" (, a multi-disciplinary research initiative that began in 2009 to enable marker-assisted breeding for rosaceous crops including peach, apple, and cherry. The long-promised yet elusive goal of routine MAB has finally been achieved for these model temperate tree fruit crops, and lessons abound for similar horticultural crops. Genetic improvement of papaya can capitalize on these recent scientific advances.

Cameron will give a presentation entitled "Enabling DNA-informed breeding for papaya: What can we learn from the RosBREED project?"

Scientific Committee

  • Maureen Fitch (USA)
  • Judy Zhu (USA)
  • Rod Drew (Australia)
  • Nguyen Minh Chau (Vietnam)
  • Geo Coppens (France)
  • Aart Louw (South Africa)
  • Pablito M. Magdalita (Philippines)
  • Richard Manshardt (USA)
  • Ray Ming (USA)
  • Sisir Mitra (India)
  • J. Pablo Morales-Payan (Puerto Rico)
  • Razean Haireen Binti Mohd Razali (Malaysia)
  • Robert Paull (USA)
  • Jorge M. Santamaria (Mexico)
  • Songpol Somsri (Thailand)
  • Paula Tenant (Jamaica)
  • Ariadne Vegas (Venezuela)
  • Osvaldo Kiyoshi Yamanishi (Brazil)
  • Shyi-Dong Yeh (Taiwan)