Molecular mapping of QTLs conferring stay-green in grain sorghum (Sorghum bicolorL. Moench)

Abstract

Drought resistance is of enormous importance in crop production. The identification of genetic factors involved in plant response to drought stress provides a strong foundation for improving drought tolerance. Stay-green is a drought resistance trait in sorghum (Sorghum bicolor L. Moench) that gives plants resistance to premature senescence under severe soil moisture stress during the post-flowering stage. The objective of this study was to map quantitative trait loci (QTLs) that control the stay-green and chlorophyll content in sorghum. By using a restriction fragment length polymorphism (RFLP) map, developed from a recombinant inbred line (RIL) population, we identified four stay-green QTLs, located on three linkage groups. The QTLs (Stg1 and Stg2) are on linkage group A, with the other two, Stg3 and Stg4, on linkage groups D and J, respectively. Two stay-green QTLs, Stg1 and Stg2, explaining 13-20% and 20-30% of the phenotypic variability, respectively, were consistently identified in all trials at different locations in two years. Three QTLs for chlorophyll content (Chl1, Chl2, and Chl3), explaining 25-30% of the phenotypic variability were also identified under post-flowering drought stress. All coincided with the three stay-green QTL regions (Stg1, Stg2, and Stg3) accounting for 46% of the phenotypic variation. The Stg1 and Stg2 regions also contain the genes for key photosynthetic enzymes, heat shock proteins, and an abscisic acid (ABA) responsive gene. Such spatial arrangement shows that linkage group A is important for drought- and heat-stress tolerance and yield production in sorghum. High-resolution mapping and cloning of the consistent stay-green QTLs may help to develop drought-resistant hybrids and to understand the mechanism of drought-induced senescence in plants.

Genetic diversity of lowland sorghum landraces assessed by morphological and microsatellite markers

“…In small cereals, ear awns, had a positive and significant correlation with grain yield and is a useful morphological marker while selecting lines for high yield under moisture stress condition (Taketa et al, 2011). Stay-green was scored as described by Xu et al (2000), the majority of the landraces showed slightly to ½ of the leaves senescent. No landrace was observed where complete foliar death.…”

Evaluation and association mapping of agronomic traits for drought tolerance in sorghum [Sorghum bicolor (L.) Moench]

“…Weekly interval irrigation was applied for the first three weeks. Starting from the fourth irrigation, water was supplied with 12 days interval till 50% flowering (Tuinstra et al, 1998;Xu et al, 2000). Irrigation was withheld when the majority of the entries reached 50% flowering creating a terminal water deficit which typifies the dry season of the semiarid tropics, where crops are usually grown on a depleted soil moisture profile.…”

Consolidated Bioprocessing Ethanol Production by Using a Mushroom

“…The plant grows to a height from about 120 to above 400 cm, depending on the variety and growing conditions, and can be an annual or a short perennial crop. Sorghum is considered to be one of the most drought resistant agricultural crops, as it is able to remain dormant during the driest periods (Xu et al, 2000). These properties of sorghum are suitable as raw material for the ethanol production.…”