title: Characterization of a Nagina22 rice mutant for heat tolerance and mapping of yield traits.
abstract: BACKGROUND
  Heat 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.
  
  
  RESULTS
  Leaf 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.
  
  
  CONCLUSIONS
  NH219 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.
authors.forename: Yugandhar
authors.initials: Y
authors.lastname: Poli
authors.forename: Ramana Kumari
authors.initials: RK
authors.lastname: Basava
authors.forename: Madhusmita
authors.initials: M
authors.lastname: Panigrahy
authors.forename: Vishnu Prasanth
authors.initials: VP
authors.lastname: Vinukonda
authors.forename: Nageswara Rao
authors.initials: NR
authors.lastname: Dokula
authors.forename: Sitapathi Rao
authors.initials: SR
authors.lastname: Voleti
authors.forename: Subrahmanyam
authors.initials: S
authors.lastname: Desiraju
authors.affiliation: Directorate of Rice Research, Rajendranagar, Hyderabad 500030, India. sarla_neelamraju@yahoo.com.
authors.forename: Sarla
authors.initials: S
authors.lastname: Neelamraju