Characterization of a Nagina22 rice mutant for heat tolerance and mapping of yield traits

Abstract

BackgroundHeat is one of the major factors that considerably limit rice production. Nagina 22 (N22) is a deep-rooted, drought and heat tolerant aus rice cultivar. This study reports the characterization of a previously isolated dark green leaf mutant N22-H-dgl219 (NH219) which showed reduced accumulation of reactive oxygen species in leaf under 40°C heat conditions.The mutant was characterized for several traits in field under ambient (38°C) and heat stress (44°C) conditions by raising temperature artificially from flowering stage till maturity by covering plants with polythene sheets during dry season 2011. Yield traits were mapped in 70 F2 segregants of IR64 × NH219 and 36 F2 segregants of its reciprocal cross.ResultsLeaf proteome analysis using two-dimensional gel electrophoresis from N22 and NH219 showed distinct constitutive expression of ribulose bisphosphate carboxylase large chain precursor (EC 4.1.1.39) in NH219 under ambient growth condition. Heat stress resulted in reduction of all 11 traits except plant height in both N22 and NH219. The extent of reduction was more in N22 than in NH219. Both pollen viability and spikelet fertility were not reduced significantly in N22 and NH219 but reduced by 20% in IR64.ConclusionNH219 is more tolerant to heat stress than wild type N22 as its percent yield reduction is lesser than N22. Single marker analysis showed significant association of RM1089 with number of tillers and yield per plant, RM423 with leaf senescence, RM584 with leaf width and RM229 with yield per plant.Electronic supplementary materialThe online version of this article (doi:10.1186/1939-8433-6-36) contains supplementary material, which is available to authorized users.

Field level evaluation of rice introgression lines for heat tolerance and validation of markers linked to spikelet fertility

“…The new genetic variations obtained from either spontaneous or induced mutants using physical or chemical mutagens can be used in crop breeding and functional genomics (Poli et al 2013). Though heat stress was the main effect that was considered in both the seasons, it cannot be ruled out that part of the effect may have been contributed by slightly decreased radiance in the poly cover house during wet season and the effect of some environmental variables other than heat in the late sown conditions of dry season.…”

“…When the plants attained booting stage, plants in 3 replications were covered with polythene sheet of 1 mm thickness (only 8-10 % cut in radiation) over metal rods to provide heat stress till maturity as shown in Supplementary Figure 1 (Poli et al (2013). The minimum and maximum temperature and relative humidity (RH) inside and outside polycover house were recorded during this period using thermo hygrometer and photometer (N.S.…”

“…Exploring the thermo tolerance diversity in rice plants will provide useful information for the improvement of traits to cope with the projected climate warming scenarios in the future (IPCC: Intergovernmental panel on climate change 2007). The impact of heat stress on rice yield depends on the genotype, the growth stage at which heat stress is received and the period of the stress (Liao et al 2014;Poli et al 2013;Zhou et al 2012;Ye et al 2011;Jagadish et al 2010a;Prasad et al 2006;Morita et al 2005). In general, when rice plants are exposed to temperature greater than 35°C for more than one hour at anthesis, it results in increased sterility (Jagadish et al 2007).…”

“…Genetic variation in the ability of rice to maintain spikelet fertility and seed set under heat stress allows selection of genotypes with increased tolerance to heat stress. QTL mapping and gene expression studies for heat tolerance have been carried out in rice at different stages such as booting, flowering and grain filling stage (Bui et al 2014;Wei et al 2013;Liao et al 2014;Poli et al 2013;Xue et al 2012;Xiao et al 2011;Ye et al 2011;Jagadish et al 2010a;Zhang et al 2008;Chen et al 2008;Zhao et al 2006). QTLs for heat tolerance were mapped on all chromosomes except chromosome 7 but fine mapping of these QTLs has not been reported.…”

“…The effect of short duration stress given only at reproductive stage may be quite different than a long duration stress where plants can acclimatize to high temperature during vegetative stage itself. Hyderabad is a good location for studies on heat stress in low humidity conditions (Poli et al 2013).…”