Identification of QTLs involved in cold tolerance in sweet × field corn

Abstract

Sweet corn was originally due to the recessive allele sugary1 (su1). Sweet corn breeders frequently use field corn genotypes for broadening the narrow genetic base of sweet corn but they have to deal with the reduced viability of su1 plants within some field corn genetic backgrounds. Emergence and seedling vigor are the most critical traits affecting the viability of su1 plants. In two populations of RILs involving sweet corn inbred lines developed from B73×P39 and B73×IL14h, a net natural selection was revealed acting against the su1 allele. In the field, 27 QTLs were detected for the RILs released from B73P39 and 24 QTLs for those from B73IL14h, while different numbers of QTLs were detected in growth chamber trials, depending on the seed origin and evaluation conditions that were not consistent across genotypes or environments. The viability of su1 is under genetic and environmental controls with significant additive effects that are probably due to multiple genes with minor contribution. There are specific genes involved in the mutant viability and these genes depend not only on the mutant and the environment but also on the genetic background into which the mutant is introduced. Some of the QTLs identified in this study explained large proportions of variance and could be used by sweet corn breeders in breeding new genotypes from field × sweet corn crosses. These results suggest that there are specific mechanisms regulating the viability of the mutant by compensating for the deleterious effect of the defective mutant.

QTL Mapping in Three Connected Populations Reveals a Set of Consensus Genomic Regions for Low Temperature Germination Ability in Zea mays L.

“… Jompuk et al (2005) detected a QTL in this region controlling PSII content of plant under early sowing (low temperature during early spring). The explained phenotypic variance of QTL in mQTL9-1 region varied from moderate in Allam et al (2016) (13.8–18.6%) and in Jompuk et al (2005) (3.6–24.8%) to low in Hu et al (2016) (5.25–8.41%). These results suggest that mQTL9-1 region also contain an important QTL for cold response, which might function at multiple growth stage and exist in multiple genetic background in maize.…”

“…In previous studies, some QTL have also been identified in this region for cold related traits by using different populations. Fracheboud et al (2002) identified a QTL for CO 2 fixation and PSII of leaves at 15°C from a RIL population; Allam et al (2016) identified a QTL associated ear height of mature plant under low temperature from another RIL population; and Hund et al (2004) identified a root trait QTL using maize seedlings grown at low temperatures. These results indicate that this region might harbor a major gene or several effective genes with pleiotropic effect on maize low temperature response at different growth stages.…”

“… Hu et al (2016) found two QTL controlling seed germination rate and seedling primary RL from the B73 × Mo17 population, with favor alleles inherited from cold tolerant line Mo17. Besides germination traits, Allam et al (2016) identified two QTL to control plant height and 100 kernel weight from populations B73 × P39 and B73 × IL14h under low temperature, with trait-increasing alleles inherited from cold tolerant line P39 and IL14h, respectively. Jompuk et al (2005) detected a QTL in this region controlling PSII content of plant under early sowing (low temperature during early spring).…”

“… Hu et al (2016) detected 6 QTL for LTGA at 18/12°C (day/night). In addition, QTL related to leaf traits of seedling, such as photosynthesis related parameters, leaf area and weight, and nitrogen content had been investigated to reflect seed vigor under cold conditions ( Fracheboud et al, 2002 ; Jompuk et al, 2005 ; Guerra-Peraza et al, 2011 ; Allam et al, 2016 ). Of these identified QTL, few were common in the same genomic regions across experiments, suggesting that QTL for maize cold tolerance are mainly determined by the specific genetic backgrounds and environmental conditions.…”

QTL Mapping Low-Temperature Germination Ability in the Maize IBM Syn10 DH Population

“…By genomewide association analyses (GWAS), 275 significant loci were associated with the traits, such as number of days from sowing to emergence, relative leaf chlorophyll content, and quantum efficiency of photosystem II, using two panels of 306 dent and 292 European flint maize inbred lines [11]. In another study, two populations of RILs involving sweet corn inbred lines developed from B73 × P39 and B73 × IL14 h were used for mapping under low temperature, and 27 QTLs were linked to increment of days to emergence and F 0 , decrease in dry weight and Fv/Fm in RILs populations of B73 × P39 and 24 QTLs in the RILs populations of B73 × IL14 h [12]. Recently, 159 quantitative trait loci (QTL) for emergence and traits related to early growth were associated by GWAS in 836 maize inbreds under cold treatment [13].…”