Reference "Quantitative trait loci for component physiological traits determining salt tolerance in rice"

Reference ID

2233

Title

Quantitative trait loci for component physiological traits determining salt tolerance in rice

Source

Plant physiology, 2001, vol. 125, pp. 406-422

Authors (5)

Koyama-M-L	Levesley-A
Koebner-R-M	Flowers-T-J
Yeo-A-R

Abstract

Rice (Oryza sativa) is sensitive to salinity, which affects one-fifth of
irrigated land worldwide. Reducing sodium and chloride uptake into rice while
maintaining potassium uptake are characteristics that would aid growth under
saline conditions. We describe genetic determinants of the net quantity of ions
transported to the shoot, clearly distinguishing between quantitative trait loci
(QTL) for the quantity of ions in a shoot and for those that affect the
concentration of an ion in the shoot. The latter coincide with QTL for
vegetative growth (vigor) and their interpretation is therefore ambiguous. We
distinguished those QTL that are independent of vigor and thus directly indicate
quantitative variation in the underlying mechanisms of ion uptake. These QTL
independently govern sodium uptake, potassium uptake, and sodium:potassium
selectivity. The QTL for sodium and potassium uptake are on different linkage
groups (chromosomes). This is consistent with the independent inheritance of
sodium and potassium uptake in the mapping population and with the
mechanistically different uptake pathways for sodium and potassium in rice under
saline conditions (apoplastic leakage and membrane transport, respectively). We
report the chromosomal location of ion transport and selectivity traits that are
compatible with agronomic needs and we indicate markers to assist selection in a
breeding program. Based upon knowledge of the underlying mechanisms of ion
uptake in rice, we argue that QTL for sodium transport are likely to act through
the control of root development, whereas QTL for potassium uptake are likely to
act through the structure or regulation of membrane-sited transport components.