M.A.N. Passos, F.L. Emediato, V.O. Cruz, C. de Camargo Teixeira, L.F. de Alencar Figueiredo, N.F. Martins, R.C. Togawa, M.M.C. Costa, O. Silva Jr., G.J. Pappas Jr., R.N.G. Miller
The development of novel approaches for crop protection requires continued advances in our understanding of the molecular mechanisms controlling plant immunity. Molecular and genomics tools have advanced our understanding, with two key branches currently recognized. In one, plant innate defense is governed by PAMP-triggered immunity (PTI), following host recognition of pathogen-associated molecular patterns (PAMPs). Successful pathogens can, however, suppress PTI signaling through evolution of specific effector proteins. Plants, in response, have co-evolved cytoplasmic resistance (R) protein receptors which establish effector-triggered immunity (ETI), a second immune system branch which recognizes specific pathogen effectors. Although banana (Musa spp.) is one of the world’s most important edible crops, contributing towards food security, a comprehensive transcriptomic dataset is not yet available for use in accelerated molecular-based breeding. In order to develop a functional genomics resource for this crop which reveals transcriptional changes during plant immunity responses to biotic stresses, we performed a pyrosequencing study of expressed genes in Musa acuminate genotypes during compatible and incompatible reactions with the fungal pathogen Mycosphaerella musicola, causal organism of Sigatoka leaf spot disease. Total RNA samples were prepared from whole plant leaf material from ‘Calcutta 4’ (M. acuminate ssp. burmannicoides, resistant) and ‘Grande Naine’ (AAA, Cavendish, susceptible), both uninfected and artificially challenged with pathogen conidiospores. Full-length enriched cDNA libraries were sequenced using a 454 GS-FLX system pyrosequencer with Titanium chemistry, generating 978,133 raw sequencing reads, with an average length of 334 bp and totaling over 460 million bp. Over 35,000 unigenes were assembled for each genotype, with approximately 35% displaying no significant similarity to any sequences in the public databases. In silico analysis identified differentially expressed genes associated with stresses and responses to biotic stimuli. Datasets were exploited for identification of expressed resistance gene analogs and defense genes, as well as large-scale SSR marker development. Together with future functional analysis and genetic map enrichment approaches, the resources generated will contribute to our understanding of plant immunity processes in Musa, facilitating long-term disease management based upon genetic improvement.
Passos, M.A.N., Emediato, F.L., Cruz, V.O., de Camargo Teixeira, C., de Alencar Figueiredo, L.F., Martins, N.F., Togawa, R.C., Costa, M.M.C., Silva Jr., O., Pappas Jr., G.J. and Miller, R.N.G. (2013). UNDERSTANDING PLANT IMMUNITY: TRANSCRIPTOME PROFILING IN MUSA-PATHOGEN INTERACTIONS USING NEXT GENERATION SEQUENCING. Acta Hortic. 986, 227-240
DOI: 10.17660/ActaHortic.2013.986.24
Musa acuminata, Mycosphaerella musicola, 454 transcriptome sequencing

Acta Horticulturae