Reference "Further characterization of two QTLs that increase phosphorus uptake of rice (Oryza sativa L.) under phosphorus deficiency"

Reference ID

7832

Title

Further characterization of two QTLs that increase phosphorus uptake of rice (Oryza sativa L.) under phosphorus deficiency

Source

Plant and Soil, 2001, vol. 237(2), pp. 275-286

Authors (2)

Wissuwa-M

Ae-N

Abstract

Four quantitative trait loci (QTLs) for P uptake were previously identified in a
rice population that had been developed from a cross between the indica landrace
Kasalath (high P uptake) with the japonica cultivar Nipponbare (low P uptake).
For further studies, near isogenic lines (NILs) were developed for a major QTL
linked to marker C443 on chromosome 12 and for a minor QTL linked to C498 on
chromosome 6. On a highly P-deficient upland soil (aerobic conditions), NIL-C443
had three to four times the P uptake of Nipponbare, whereas the advantage of NIL-
C498 was in the range of 60-90%. The superiority of NILs over Nipponbare
vanished when grown in the same soil under anaerobic paddy conditions. All
genotypes had high P uptake when P was supplied at a rate of 60 kg P ha-1,
regardless of soil conditions. These results confirmed the presence of both QTLs
and furthermore implied that QTLs affected absorption mechanisms that
specifically increased P uptake in a P deficient upland soil. Additional
experiments were conducted to investigate if the effect of QTLs is linked to an
increase in root growth or due to more efficient P uptake per unit root size
(higher root efficiency). Root size did not differ significantly between
genotypes in the plus-P treatment. P deficiency, however, reduced the root
surface area of Nipponbare by more than 80% whereas NIL-C443 maintained almost
half of its non-stress root surface area. The low root growth of Nipponbare
observed under P deficiency was probably the result of insufficient P uptake to
sustain plant growth, including root growth. Genotypic differences in the
ability to maintain root growth, therefore are likely caused by some mechanism
that increases the efficiency of roots to access P forms not readily available.
This however, only had an effect in aerobic soil. Potential mechanisms leading
to higher P uptake of NILs are discussed.