Background and Aims Endoparasitic root-knot nematodes (RKNs) (Meloidogyne spp.) cause considerable losses in banana (Musa spp.), with Meloidogyne incognita a predominant species in Cavendish sub-group bananas. This study investigates the root transcriptome in Musa acuminata genotypes 4297-06 (AA) and Cavendish Grande Naine (CAV; AAA) during early compatible interactions with M. incognita.Methods Roots were analysed by brightfield light microscopy over a 35 d period to examine nematode penetration and morphological cell transformation. RNA samples were extracted 3, 7 and 10 days after inoculation (DAI) with nematode J2 juveniles, and cDNA libraries were sequenced using lllumina HiSeq technology. Sequences were mapped to the M. acuminata ssp. malaccensis var. Pahang genome sequence, differentially expressed genes (DEGs) identified and transcript representation determined by gene set enrichment and pathway mapping.Key Results Microscopic analysis revealed a life cycle of M. incognita completing in 24 d in CAV and 27 d in 4279-06. Comparable numbers of DEGs were up-and downregulated in each genotype, with potential involvement of many in early host defence responses involving reactive oxygen species and jasmonate/ethylene signalling. DEGs revealed concomitant auxin metabolism and cell wall modification processes likely to be involved in giant cell formation. Notable transcripts related to host defence included those coding for leucine-rich repeat receptorlike serine/threonine-protein kinases, peroxidases, thaumatin-like pathogenesis-related proteins, and DREB, ERF, MYB, NAC and WRKY transcription factors. Transcripts related to giant cell development included indole acetic acid-amido synthetase GH3.8 genes, involved in auxin metabolism, as well as genes encoding expansins and hydrolases, involved in cell wall modification.Conclusions Expression analysis in M. acuminata during compatible interactions with RKNs provides insights into genes modulated during infection and giant cell formation. Increased understanding of both defence responses to limit parasitism during compatible interactions and effector-targeted host genes in this complex interaction will facilitate the development of genetic improvement measures for RKNs.

This study evaluated the effects of mining practices using soil nematodes as bioindicators. Soil samples represented four different subsystems found in the CeBio Research Center, including natural/undisturbed (rainforest (RF) and savannah (SA)) and disturbed (Eucalyptus spp. (EU) and grassland (GR)) subsystems. Ecological descriptors S (3.5-9.5), d (1.22-4.23) and MI (1.9-3.23) significantly differentiated the subsystem GR (high impact) from the other subsystems. Additionally, poorly covered soil (i.e., subsystem GR) negatively influenced the composition of nematode assemblages, and primarily so for nematodes with high c-p values. Among soil variables, pH strongly influenced the distribution of soil nematodes, negatively affecting the abundance of all c-p groups and diversity of nematodes. On the other hand, pH also positively affected FF and PP trophic groups in the subsystem GR. The similarity of subsystem EU and natural subsystems (RF and SA) suggests that soil restoration with Eucalyptus spp. appears to be an adequate management practice to promote the recovery of areas subjected to mining practices.