QTL-Seq Identifies QTL for Relative Electrical Conductivity Associated with Heat Tolerance in Bottle Gourd (Lagenaria Siceraria)

Abstract

Heat is a major abiotic stressor seriously affects watermelon produce; however, its effects may be mitigated through grafting onto heat tolerant bottle gourd rootstock. To understand the genetic basis and select reliable markers are necessary in the variety breeding process. In this paper, the relative electric conductivity (REC) was used as a visual indicator for heat stress to study the genetics and SNP marker of heat tolerance in bottle gourd via QTL-seq approach. The results showed that recessive inheritance and a major QTL locus controlled REC related to heat tolerance. Seven heat-tolerant loci (qHT1.1, qHT2.1, qHT2.2, qHT5.1, qHT6.1, qHT7.1, and qHT8.1) exhibited high {Delta}(SNP-index) values (ranging from 0.19-0.38), and of these, the greatest value (0.32, P < 0.01) and greatest number of detected SNPs (9052) were found in chromosome 2 at qHT2.1 region (11.03 - 19.25 Mb); qHT2.1was taken as a promising major QTL for heat tolerance in bottle gourd. A total of 34 putative candidate genes related to heat stress were detected within the qHT2.1 region. Three polymorphic SNPs (BG_GLEAN_10022642, BG_GLEAN_10022727, and BG_GLEAN_10022589) that are involved in pollen sterility, intracellular transport, and signal recognition were validated and exhibited significant marker-trait association that could be used in heat tolerant molecular breeding for bottle gourd. The qHT2.1region is an important finding can be used for fine mapping and discovering new genes associated with heat tolerance in bottle gourd.