Abstract
BackgroundStomata regulate photosynthesis and transpiration, and these processes are critical for plant responses to abiotic stresses such as salinity. A barley double haploid population with 108 lines derived from a cross between CM72 (salt-tolerant) and Gairdner (salt-sensitive) was used to detect quantitative trait loci (QTLs) associated with stomatal and photosynthetic traits related to salinity tolerance.ResultsA total of 11 significant QTLs (LOD > 3.0) and 11 tentative QTLs (2.5 < LOD < 3.0) were identified. These QTLs are distributed on all the seven chromosomes, except 5H and explain 9.5–17.3% of the phenotypic variation. QTLs for biomass, intercellular CO2 concentration, transpiration rate and stomatal conductance under control conditions co-localised together. A QTL for biomass also co-located with one for transpiration rate under salinity stress. A linkage was found between stomatal pore area and gas exchange. A QTL for salinity tolerance also co-localised with QTLs for grain yield and biomass on chromosome 3H. Based on the draft barley genome, the candidate genes for salinity tolerance at this locus are proposed.ConclusionsThe lack of major QTLs for gas exchange and stomatal traits under control and saline conditions indicates a complex relationship between salinity and leaf gas exchange due to the fact that these complex quantitative traits are under the control of multiple genes.
Highlights
Stomata regulate photosynthesis and transpiration, and these processes are critical for plant responses to abiotic stresses such as salinity
The double haploid (DH) and parental lines show a large diversity in salinity tolerance Significant differences in stomatal and photosynthetic traits between parental line CM72 and Gairdner were described in Liu et al [26]
Shown are stomatal pore area (a, b), aperture width/length (c, d), subsidiary cell length (e, f), subsidiary cell width (h, i) and subsidiary cell volume (j, k) of DH lines derived from the cross of CM72 and Gairdner, under control and salinity treatment conditions
Summary
Stomata regulate photosynthesis and transpiration, and these processes are critical for plant responses to abiotic stresses such as salinity. Salinity is causing major global food security issues due to the large arable area that is saline and not suitable for cropping; breeding salt tolerant crops has become a top priority. Genetic modification to produce transgenic plants containing novel genes or different expression levels of existing genes can improve plant salt tolerance [3]. Salinity tolerance is controlled by multi-gene traits, where genes are expressed. Stomata control the exchange of water vapour and CO2 between the leaf interior and the atmosphere, and serve as major gateways for CO2 influx into plants as well as transpirational water loss from plants [7,8,9].
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