Introgressed eggplant lines with the wild Solanum incanum evaluated under drought stress conditions1

Abstract

As access to irrigation water becomes increasingly limited, introgression of relevant genomic regions from drought-tolerant wild genotypes is a promising breeding strategy for crop plants. In this study, nine eggplant (Solanum melongena) introgression lines (ILs) covering altogether 71.6% of the genome of the donor wild relative parent S. incanum were evaluated for drought tolerance under water stress conditions. Plants at the five true leaves stage were irrigated at either 100% (control) or 30% (water stress) field capacity for 14 days, and growth and biochemical traits were measured. Reduced irrigation resulted in decreased growth and increased levels of stress markers such as proline and malondialdehyde. Most ILs had lower growth and biomass production than the cultivated parent under both conditions. However, the wild alleles for two genomic regions related to stem and root dry weight (dwt8 and dwr6%) conferred improved tolerance to water stress. In addition, several S. incanum alleles had a positive effect on important traits that may improve yield under drought conditions, such as leaf water content (lwc12%), water use efficiency (wue1%) and chlorophyll content (chl2 and chl8%). Fine-mapping of the genomic regions for tolerance and reducing linkage drag with regions affecting growth will be crucial for significantly improving eggplant drought tolerance through introgression breeding.