Resistance to root-lesion nematode Pratylenchus neglectus identified in a new collection of two wild chickpea species (Cicer reticulatum and C. echinospermum) from Turkey

Chickpea (Cicer arietinum) is a major legume crop, with Australia being the second largest producer worldwide. Pratylenchus neglectus is a root-lesion nematode that invades, feeds and reproduces in roots of pulse and cereal crops. In Australia, chickpea and wheat (Triticum aestivum) are commonly grown in rotation and annual damage by P. neglectus accounts for large economic losses to both crops. Cultivated chickpea has narrow genetic diversity that limits the potential for improvement in resistance breeding. New collections of wild chickpea species, C. reticulatum and C. echinospermum, have substantially increased the previously limited world collection of wild Cicer germplasm and offer potential to widen the genetic diversity of cultivated chickpea through the identification of accessions with good resistance. This research assessed 243 C. reticulatum and 86 C. echinospermum accessions for response to P. neglectus in replicated experiments under controlled glasshouse conditions from 2013 and 2014 collection missions that were received, tested and analysed in two experimental sets. Multi-experiment analyses showed lower P. neglectus population densities in both sets of wild Cicer accessions tested than Australia's elite breeding cultivar PBA HatTrick at the significance level p < 0.05. Provisional resistance ratings were given to all genotypes tested in both experimental sets, with C. reticulatum accessions CudiB_008B and Kayat_066 rated as resistant in both Set 1 and Set 2. New sources of resistance to P. neglectus observed in this study can be introgressed into commercial chickpea cultivars to improve their resistance to this nematode.     

Interaction of root-lesion nematodes, Pratylenchus thornei and P. crenatus, with the fungus Thielaviopsis basicola and a grey sterile fungus on roots of pea (Pisum sativum)

Pratylenchus thornei invaded excised pea roots in agar in greater numbers and penetrated the cortex more deeply than P. crenatus . Both species fed on the roots ectoparasitically and displaced root cells into the surrounding medium. The cytoplasm of cortical cells near cither nematode became granulated, with enlarged vacuoles and nuclei. P. thornei also caused these responses in the endodermis. Infection of the root surface with a grey sterile fungus inhibited invasion by P. crenatus and P. thornei . Infection by Thielaviopsis basicola inhibited P. thornei invasion but encouraged penetration by P. crenatus and the hyphae were found deeper in the cortex when P. crenatus was present.