Characterization of Sugarcane QTLs for Tillering and stalks Quality through a Two-Way Pseudo-Testcross

Abstract

Sugarcane is grown worldwide from cultivars with complex genetic constitutions. Tillers and effective stalks are important agronomic traits of sugarcane that play important roles in yield. Using a two-way pseudo-testcross mapping strategy, we obtained a total of 172 F1 population of Yuenong73-204 (low tillering sugarcane variety) × CP72-1210 (ultra-high tillering germplasm), then, a total length of 1578.04 cM genetic map was constructed using 572 polymorphism SNPs genotyped by chip array. In addition, sprouts, tillers, and effective stalks of the F1 population were collected from four different environments. The total number of sprouts and tillers and the number of effective stalks were significantly positively correlated. The broad-sense heritability of tiller rate and effective stalk ranged 0.44, from 0.74. Quantitative trait loci (QTL) mapping showed 5 QTLs associated with tillers and 5 QTLs associated with effective stalks, one of which was identified in at least two environments. The phenotypic contribution rates of these (QTLs) ranged from 7.7–11.1% for tillers and 5.6–10.7% for effective stalks. A total number of 23 candidate genes, including 5 transcription factors and 5 proteins, were further identified in these QTLs intervals, among which the C2H2 transcription factor and E3 ubiquitin-protein ligase were the most significantly expressed in tillers and the effective stalk. These findings provide a reference for the genetic improvement of tillers and effective stalks of sugarcane.