Members of the ProMusa network have joined forces to take on the challenge posed by banana streak viruses (BSV). DNA sequences of these badnaviruses are integrated in the B genome donated by the wild species Musa balbisiana. The ability of some of the sequences to form infective particles has led to restrictions on the distribution and use of B-genome-rich cultivars. Certain institutions have even stopped using cultivars containing the B genome in their breeding schemes. But if these cultivars are anything like their balbisiana ancestor, they could be more tolerant to drought than cultivars derived only from Musa acuminata, which donated the A genome, and as such play an important role in safeguarding future banana production against the effects of climate change.
In response to a call for proposals on “Enhancing the Value of Crop Diversity in a World of Climate Change”, ProMusa members in the Philippines, France and Australia received funding from the Global Crop Diversity Trust (Trust), the Generation Challenge Programme (GCP) and the Global Partnership Initiative for Plant Breeding Capacity Building (GIPB) to tackle this problem.
The Trust-supported work will focus on assessing, under greenhouse and field conditions, the drought tolerance of wild and edible B-genome, as well as some A-genome, accessions from two collections in the Philippines. GCP will support the characterization of these materials using molecular markers that distinguish between infectious and non-infectious integrated BSV sequences, whereas the GIPB-funded project will assess the impact of drought on the activation of endogenous BSV sequences.
This approach will provide the basis for identifying Musa genotypes that are better adapted to drought and less prone to activation of endogenous BSVs. The results will be of direct use to banana breeders who wish to exploit the full range of genetic diversity for incorporating resistance and tolerance traits in their breeding programmes.
Meanwhile, preliminary results of screening work done during the first phase of the CIALCA project do indicate that A-genome accessions grow more slowly than B-genome cultivars when subjected to mild drought stress. Pot trials revealed that the East African highland banana Mpologoma (AAA) is more sensitive to drought than Sukali Ndizi (AB). Tests on meristems revealed that half of the Musa acuminata wild type Calcutta 4 did not survive losing 40% of their water content, whereas half of the Musa balbisiana could withstand losing 60% of their water content before they died. Click here for an excerpt from the phase 1 report of the project.