Researchers develop a new way to describe plantain diversity in DRC

Researchers studying the morphological (structure and form) diversity of plantain in the Democratic Republic of Congo (DRC) have developed an innovative way to describe plantain diversity using descriptors based on performance, grouping them into main, secondary, and rare descriptors.

The morphological identification of plantain cultivars is important since molecular tools appear to have little value in supporting research in plantain taxonomy to differentiate plantain cultivars.

Three new descriptors

In the new system, three sets of descriptors are used: the first are the main descriptors such as bunch size and orientation, plant size and height, which allow a quick and easy separation of plantain cultivars.

Bunch type was a major striking difference and quickly separated plantain cultivars into three main types. Other striking differences were the size of the pseudostem or trunk (giant, medium-sized, and small-sized) and the bunch orientation (which was generally pendulous or subhorizontal, and rarely horizontal and erect).

The secondary descriptors allow the differentiation of one cultivar from another within the same main group of bunch type, pseudostem size, or bunch orientation. Multiple secondary descriptors include pseudostem color, immature fruit peel color, fruit shape, fruit apex, fruit position, number of hands, fruit size, number of fingers per hand, and flower relicts at the fruit apex.

The third set are the rare descriptors, which allow the differentiation of one cultivar from all the others in the subgroup.

According to the researchers, this approach proved useful in differentiating the nearly 100 plantain accessions in the collection of the University of Kisangani (UNIKIS) in DRC. This approach makes cultivar description logical and faster because it moves from general to particular characteristics.

The study, titled The morphological diversity of plantain in the Democratic Republic of Congo by J.G. Adheka, D.B. Dhed’a, D. Karamura, G. Blomme, R. Swennen, and E. De Langhe, focused on the morphological characterization of plantain cultivars collected in the period 2005–2014 in 280 villages across nine provinces of DRC. These cultivars were established in two field collections at UNIKIS.

Picture of A False Horn plantain variety called Tala Lola from Central DR Congo
A False Horn plantain variety called ‘Tala Lola’ from Central DR Congo

Most of the collected cultivars were French plantains (64 out of 98), followed by False Horn (23) and Horn (10) plantains.

Banana cultivars are usually described using Descriptors for bananas (Musa spp.) developed by IPGRI-INIBAP/CIRAD in 1996. The researchers had adapted these existing descriptors to better differentiate the variation and improve future research on plantains. This new work, published in Scientia Horticulturae, however, showed that this descriptor list is not appropriate for describing variation within the plantain subgroup, with 77 out of a total of 117 descriptors not considered useful.

The researchers believe that this existing descriptor list for banana will also not be appropriate in describing variation within other subgroups of banana, like the East African Highland banana, Pacific plantain, etc.

The observed variation was reproduced in the collection during succeeding cycles and confirmed the stability of the cultivars, as well as the value of the new descriptors. The classification of the plantain cultivars at the UNIKIS collection can be used as a standard for investigating plantain diversity for the entire African continent.

Large plantain diversity in DRC

The study results showed that the humid zone of DRC contains an exceptionally large diversity of plantains among the edible Musa subgroups. This means that DRC also has the largest diversity of plantains in Africa. The 100 different cultivars covered in the study represent just a part of the entire plantain variability zone in DRC. More cultivars are expected to be found in regions of the country that still need to be explored. The researchers believe that the diversity of plantain in DRC could be substantially larger than 120 cultivars.

Picture of A Horn plantain variety called Ikpolo Noir found in DR Congo
A Horn plantain variety called ‘Ikpolo Noir’ found in DR Congo

Plantain characterization data from DRC offer a platform for reflections on the pan-African scale of plantain diversity. Assessing and characterizing the complete plantain diversity in Africa is possible by compiling characterization results of all Central and West African countries whereby UNIKIS in DRC will play a key role given its expertise and access to the largest plantain variability.

Since the planting of all accessions in one location is not feasible due to financial constraints, the researchers encouraged plantain curators to continue intensive contact, with regular exchange visits and discussions, to progressively reach an agreement on classification, synonymy, and uniqueness of all plantain cultivars.

In sub-Saharan Africa, an estimated 30 million people depend on banana as the principal source of dietary carbohydrate, with small-scale farmers making up the vast majority of banana and plantain producers. They grow the crop mainly for home consumption or for local markets. In West and Central Africa, about two-thirds of the banana cultivated and produced are plantain, which need to be processed and/or cooked for consumption.

The other third consists of dessert and other cooking bananas. In Africa, the major producing countries are Cameroon, Ghana, Nigeria, and Côte d’Ivoire. According to the FAO, production of plantain in these countries ranks high (12.3 million tons in 2014) among the starchy staples.

The study was conducted as part of a collaboration of researchers from University of Kisangani (UNIKIS), IITA, Bioversity International, and the Laboratory of Tropical Crop Improvement, Division of Crop Biotechnics, Katholieke Universiteit, Belgium.

Media contact: Katherine Lopez, k.lopez@cgiar.org

IITA and partners conduct first proteomic investigation in plantain and banana

Scientists from IITA and partner institutions have carried out the first known proteomic investigation into plantain. The results of the study are featured in a paper, titled “The plantain proteome, a focus on allele specific proteins obtained from plantain fruits” by N.A. Campos, R. Swennen, and S.C. Carpentier. Proteomics entails the study of the expression of proteins in a cell or organism. This is important because proteins are responsible for both the structure and the functions of all living things.

Picture of Plantain fruit. Nádia Campos, KU Leuven.
Plantain fruit. Nádia Campos, KU Leuven.

IITA banana breeder Rony Swennen said the identification and public release of the plantain fruit proteome is an important step for plantain varietal selection and breeding. He said the research is important because little attention has been given to postharvest research in plantain, a staple especially in Central and West Africa and Latin America, which grows most of the world’s plantains.

Fruit development and maturation in plantain is hardly studied unlike in the more popular dessert banana. As a result, he said plantain suffers from many pests and diseases, although it is currently bred for higher yield. The acceptance of new plantain hybrids by farmers needs to be accelerated, hence the importance of better understanding the fruit physiology of plantain to develop hybrids that are more acceptable to consumers and have a better shelf life.

The proteomic research into plantain used an easy and reproducible procedure for protein extraction and identification, resulting in the first proteome (set of proteins) of plantain fruits. The results were compared with the proteome from the dessert banana Cavendish.

The scientists found that both the plantain and Cavendish cultivars were relatively close genetically but showed contrasting phenotypic or physical differences such as size, texture, color of fruit, and flavor. These characteristics, the scientists said, comes from a different physiology and maturation process.

The plantain fruit preserves more starch for longer periods than sweet banana. The type of starch also differs. According to the scientists, there are two types of starch in banana: resistant starch (RS) and non-resistant starch. This classification is linked to the capacity to be digested by the human body. Plantain degrades RS faster, but at maturation, is richer in resistant starch.

The paper concluded that an improved understanding of the fruit maturation process may yield benefits for public health, farming, and agricultural business.

The study was conducted as part of a collaboration of researchers from IITA, the Laboratory of Tropical Crop Improvement, Division of Crop Biotechnics, Katholieke Universiteit, Belgium, and SYBIOMA: Facility for SYstems BIOlogy based MAss spectrometry, KU Leuven.

Media contact: Katherine Lopez, k.lopez@cgiar.org

First banana hybrids bred in Arusha go for field trials

Three years after starting its activities, the IITA banana breeding team based in Arusha-Tanzania has planted its first banana hybrids for field evaluation. While this is a major milestone for the program, it also underscores the complexity and slow pace of banana breeding.

Dr Brigitte Uwimana, planting the hybrid banana in the trial field in Arusha.
Dr Brigitte Uwimana, planting the hybrid banana in the trial field in Arusha.

The program started its activities in Arusha in early 2011 after many years of successful banana breeding in Nigeria (for plantain) and Uganda (for matooke or highland cooking bananas) in collaboration with the National Agricultural Research Organization (NARO).

In Tanzania, the breeding is focusing on Mchare, an important group of cooking banana varieties in the Arusha-Kilimanjaro region and in other East African countries. This breeding program aims to develop Mchare banana varieties that are high yielding with resistance to Fusarium wilt, a soil-borne fungal disease that is attacking the crop in Tanzania. “This breeding program follows two main streams. One stream targets crosses to gather information to accelerate banana breeding. The other target crosses that aim at producing improved Mchare,” said Dr Brigitte Uwimana, the postdoc banana breeder based in Arusha.

“Banana breeding is a tedious undertaking, mainly because banana are sterile and don’t generally produce seeds (parthenocarpy). This makes the generation of new hybrids a challenge. These hybrids will be evaluated in the field and the best will be selected for further breeding Mchare banana,” Brigitte explained.

The successful breeding of the new hybrids involves the selection of fertile parents, seed extraction, seed germination in the laboratory, and nursery management.

Alliance reviews pilot control strategies for banana bunchy top disease in Africa

Members of the Alliance for Banana Bunchy Top Disease (BBTD) Control in Africa met at IITA, Ibadan, Nigeria, 9-14 March, to share progress made during the first year of pilot site implementation in eight countries in sub-Saharan Africa and to develop follow-up action.

The meeting was attended by about 50 implementing partners from 11 countries. It provided a platform for refining the protocols for studying the BBTD epidemiology; mapping household and community social practices; ensuring clean seed production and supply; and developing a plan that consolidated and improved shared learning for implementation in 2015.

Meeting participants in a group photo.
Meeting participants in a group photo.

BBTD, caused by the Banana bunchy top virus (BBTV), is the most devastating disease of banana for which no sources of resistance are available. The disease is spread through infected planting material and also by an insect vector—the banana aphid.

Banana is one of the key staple crops supporting the livelihoods of an estimated 100 million people, most of who live in sub-Saharan Africa. Over 50% of the world’s production of banana (and plantain) is grown in the region.

Bunchy top was first reported from Africa in 1901 and has spread extensively into new production areas during the last two decades. It recently invaded Bénin and Nigeria in West Africa and had a limited spread within the Kivu provinces of DR Congo, neighbor to Uganda, the largest banana-producing country in Africa. Currently, BBTD occurrence has been confirmed in 13 countries in sub-Saharan Africa.

Alliance member-partners from the national programs visit the Genetic Resources Center.
Alliance member-partners from the national programs visit the Genetic Resources Center.

In February 2013, experts under the umbrella of the CGIAR Research Program on Roots, Tubers and Bananas (RTB) formed an alliance to implement medium and long-term strategies to control BBTD in sub-Saharan Africa. The ongoing initiative under this framework, Banana bunchy top disease containment and recovery in sub-Saharan Africa: Building capacity and piloting field recovery approaches through a learning alliance is led by IITA, Bioversity International, CIRAD, together with national partners in Bénin, Burundi, Cameroon, Congo Brazzaville, DR Congo, Ghana, Malawi, and Nigeria.

The alliance is focused on field-scale approaches to the recovery of BBTD-infested areas. This includes (i) Eradication of infected plants, (ii) Design of a supply flow for BBTV-free planting material, (iii) Establishment of clean fields in the banana-free zone with virus-free planting material; and (iv) Development of capacity for disease diagnosis and control, including training farmers in producing clean planting material.

“All sites have partnered with new communities to establish banana-free fallows and a supply chain for BBTV-free planting material and these partnerships are working well” said Charles Staver of Bioversity International. He also emphasized that the success of the alliance lay in the strength of the partnerships. The project is building on previous work to assess the extent of BBTV spread in the target countries. It evaluates banana and plantain landraces and synthetic hybrids in endemic sites to assess their performance against BBTD and the banana aphid. “This work has shown some Musa cultivars with a high degree of tolerance to BBTD that can be used in endemic areas,” said Rachid Hanna, Entomologist, IITA-Cameroon.

Alliance members during a tour of IITA banana fields in Ibadan, Nigeria, led by Lava Kumar (extreme right).
Alliance members during a tour of IITA banana fields in Ibadan, Nigeria, led by Lava Kumar (extreme right).

“Training in developing diagnostic skills is one of the focus areas of the project. Pilot sites have started to adopt diagnostic protocols for virus indexing following the training course held in July 2014 in Montpellier,”
said Marie-Line Caruana, Virologist, CIRAD.

The project has also focused on building research capacity through three PhD and five MSc students on aspects of the cropping system, epidemiology and ecology of BBTD, varietal reaction to disease, and socioeconomic studies. The project has partnered with the gender and socioeconomic group of RTB to identify the household and community dimensions to mobilizing recovery areas from BBTD.

“The pilot sites are proving to be effective platforms for testing new strategies and technologies, learning and forming excellent in-situ avenues for training and capacity strengthening. The pilot zone concept can be scaled up and scaled out in the eight target countries and expanded to five
other BBTD-affected countries (Angola, Central African Republic, Equatorial Guinea, Rwanda, and Zambia) in
the next phase,” said Lava Kumar, Virologist and workshop organizer, IITA-Nigeria.

A session on ‘innovations’ was organized as part of this workshop and dealt with the latest initiatives to tackle BBTD through understanding virus-host-vector interactions, disease impact on planting material degeneration, transgenic approaches to develop resistance to BBTV and the banana aphid, understanding vector dynamics in relation to climate change, new propagation technologies using tissue culture and bioreactors, and the potential for youth agripreneurs in banana seed production. Experiences and lessons from BBTD management efforts in Australia were shared by John Thomas, Virologist from the University of Queensland, Brisbane, who attended as an external expert and appreciated the efforts of the alliance to control BBTD.

The representative from the Nigeria Phytosanitary Service gives a talk.
The representative from the Nigeria Phytosanitary Service gives a talk.

Participants were exposed to the phytosanitary and indexing procedures used to generate healthy planting material, the in-vitro conservation of Musa in the IITA gene bank, and the breeder’s reference collection in the field.

As part of the program, participants visited BBTD-affected areas in Idologun, Ogun State, which is also the base for the Nigerian pilot site and interacted with farmers and community leaders about the action being taken to mitigate BBTD. Sunday Akinyemi (NIHORT) and Charles Onyeani (NAQS) outlined the scheme being used to recover banana production in the pilot site. Dr Claude Mvila from Congo Republic appreciated the involvement of the entire community, from leaders to laborers, in this initiative.

Giant strides in IITA plantain breeding for West Africa

 

Amah during her contract review seminar
Amah during her contract review seminar

IITA has made significant progress in its plantain research in West Africa with the generation of seedlings from crosses with in vitro induced tetraploids from diploids―a first for the Institute.

The IITA Regional Banana Breeding Manager, Delphine Amah, who supervised execution of the crosses in IITA-Ibadan, said the crosses were vital for plantain improvement in West Africa in the years ahead.

Delivering her contract review seminar titled: Support to Banana and Plantain Breeding―Updates on West Africa, Amah said the Banana Unit had recorded giant strides in the recent years.

For instance, as part of a revised pre-breeding strategy to produce improved parents while shortening the breeding cycle for plantain, the unit was now producing tetraploids which have four sets of chromosomes from diploids (which have two) using optimized in vitro doubling techniques.

In addition, tissue culture techniques have been employed to generate seedlings from crosses through embryo culture and mass propagation of plants for clonal evaluation.

The unit is also promoting the use of macropropagation and field propagation techniques for the production of clean planting material and good agronomy practices.

So far, Amah and her team have produced and distributed thousands of Agbagba plantain plantlets to the IITA farm unit and Youth Agripreneur project for propagation and distribution.

Furthermore, they have established pollination blocks with female fertile plantain landraces and Black Sigatoka resistant tetraploid plantain hybrids for accelerated breeding.

The team has established recently imported Musa acuminata ssp. banksii accessions for evaluation and use as parents in crosses to breed for plantains with high provitamin A content.

They have also established a propagation scheme for the production of plantlets for pollination blocks and planned trials to enable registration of new IITA hybrids.

All these activities are aimed at rejuvenating plantain breeding in IITA for efficient delivery of improved varieties to farmers, she said.