IDENTIFICATION OF MICROSATELLITE MARKERS LINKED TO BACTERIAL WILT RESISTANCE IN AFRICAN EGGPLANT

Abstract

Bacterial wilt (BW) is distributed throughout the world and cause up to 100% yield loss of many solanaceous crops Management of this soil borne bacterium mainly rely on chemical use which is ineffective and eco-unfriendly. However, use of resistant eggplants and non-chemical strategies can be a good alternative for BW management. The objectives of the study are to determine phenotypic reaction of eggplant to BW and identify eggplant bacterial wilt resistant markers. The African eggplants seeds were supplied by AVRDC-RCA, Arusha. They were raised in cocopeat in trays and transplanted at five true leaves (July–September 2016 and February–June 2019). Symptom severity was scored using a 1-5 scale for each accession. A total of 15 primers were screened for bacterial wilt resistance. In susceptible accessions, symptoms appeared 14 days after field transplanting and 21 days’ post inoculation. After the assay, eggplant stem sections were sampled and put under sterile water for 2 hours to allow BW to ooze out. Further, 50ul of the suspension was streaked on TZC media, incubated at 28^oC for 48 hours. Bacterial wilt symptoms varied from one leaf wilt to whole plant death. The symptoms were first observed on upper leaves and progressed to other parts of the plant resulting to wilting. Brown disclouration in vascular systems of transversely cut stem sections was observed. Four accessions, i.e., RV100438, RV100246, RV100242 and RV100455 recorded a disease severity of ≤ 1.2. Twelve accessions, i.e., RV100386, RV100234, RV100201, RV100245, RV100331, RV100250, RV100447, RV100161, RV100247, RV100240, RV100271, RV100458 2.7-3.4. Accessions from Solanum aethiopicum and S. anguivi showed resistance at 1.1 – 1.3 severity and none showed full resistant. Of the 15 markers used, only 5, i.e., ecm009, mk03O04, ecm001, SOL5036 and emiO4P17 showed polymorphism between the R and S eggplants. Resistant eggplant accessions are therefore recommended for cultivation under integrated systems and used in breeding resistant eggplants.