Field evaluation of cotton near-isogenic lines introgressed with QTLs for productivity and drought related traits
Levi A, Paterson A H, Barak V, Yakir D, Wang B, Chee P , Saranga Y. 2009
Mol Breeding 23:179–195.
Quantitative trait loci (QTLs) for yield and drought related physiological traits, osmotic
potential (OP), carbon isotope ratio (d13C, an indicator of water use efficiency), and leaf chlorophyll
content (Chl), were exchanged via marker-assisted selection (MAS) between elite cultivars of the two
cotton species Gossypium barbadense cv. F-177 and G. hirsutum cv. Siv’on. The resulting near isogenic
lines (NILs) were examined in two field trials, each with two irrigation regimes, in order to (1) evaluate
the potential to improve cotton drought resistance by MAS and (2) test the role of physiological traits in
plant productivity. NILs introgressed with QTLs for high yield rarely exhibited an advantage in yield
relative to the recipient parent, whereas a considerable number of NILs exhibited the expected phenotype in
terms of lower OP (5 out of 9), higher d13C (4 out of 6) or high Chl (2 out of 3). Several NILs exhibited
considerable modifications in non-targeted traits including leaf morphology, stomatal conductance
and specific leaf weight (SLW). In G. barbadense genotypes, yield was correlated negatively with d13C
and OP and positively with stomatal conductance, SLW and Chl, whereas in G. hirsutum yield was
negatively correlated with d13C, SLW and Chl. This dissimilarity suggests that each of the respective
species has evolved different mechanisms underlying plant productivity. We conclude that the improvement of drought related traits in cotton NILs may lead to improved drought resistance via MAS, but that conventional breeding may be necessary to combine the introduced QTL(s) with high yield potential.
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