Vol. 21 >B. Research Notes>III. Genetics of physiological traits and others |
14. | Detection of QTLs for zinc toxicity tolerance in rice (Oryza sativa L.) |
Y.J. DONG*1, T. OGAWA1, H. KAMIUNTEN1, D.Z LIN1, S.H. CHENG2,
H. TERAO1 and M. MATSUO1 1) Agricultural Faculty, Miyazaki University, Miyazaki City, 889-2192, Japan 2) China National Rice Research Institute, Hangzhou, 310006, China * Corresponding author (dong@cc.miyazaki-u.ac.jp) |
Zn2+ deficiencies and excess all harms the growth of rice
plant and Zn2+ excess toxicity easily occurs in acid soil (Obata,
1995). It was reported that no significant effects on rice growth were
observed until 600ppm of Zn2+ concentration (Takenaga, 1995).
In this study, the 71 recombinant inbred (RI) lines from a cross of Asominori
with IR24, the molecular data and RFLP map with 375 markers (Tsunematsu
et al. 1996), kindly provided by Prof. A. Yoshimura (Kyushu University,
Japan) was used to detect QTLs for zinc toxicity tolerance (ZNT) in rice.
In this experiment, ten germinated seeds for each RI line including 'Asominori'
and 'IR24' were sown at each hill [2.5(L) x 2.5(W) x 4.4(H)
cm] in a nursery seeding bed (Made in Takii Seed Co. Japan) filled with
commercial heated soil (Made in Miyazaki Yamamune Commercial and placed
at outdoor on May, 17, 2004, and soaked in 1000ppm Zn2+ solution
(pH = 5.4) from the 20th day after sowing. The solution was replaced every
two days and the toxicity in rice seedlings was examined 20d after treatment
and classified into 11 (from 0 to 10) degrees according to the leaf bronzing
severity, where one plant without almost leaf bronzing was determined
as "0" and one with all leaf bronzing as "10". All
treatments were replicated two times and the average values were used
for QTL analysis. The QTL analysis was performed with QTL Cartographer
version. 2.0 (Wang et al., 2003) using composite interval mapping
(CIM) method. The CIM analysis was calculated using forward regression,
the walk speed of 2 cM, and the window size of 10 cM. The locus with LOD
score greater than 2.0 was considered as indicative of the presence of
a QTL. was a clear difference for ZNT between Asominori (high tolerant) and
IR24 (susceptible). Three QTLs, tentatively designated as qZNT-1,
qZNT-3, and qZNT-10, were detected for ZNT with LOD value
of 6.0 (chromosome 1), 3.2 (chromosome 3) and 2.2 (chromosome 10) (Table
1 and Figure 2) and explained 21.9%, 8.9% and 7.6% of total phenotypic
variation respectively. The Asominori allele in qZNT-1 contributed
to the increase of ZNT, whereas qZNT-3, and qZNT-10 alleles
decreased the trait, which confirmed the continuous variation and transgressive
segregation for leaf bronzing degrees in RI population (Fig. 1). The results
and the tightly linked molecular markers that flank the QTLs might be
useful in breeding for high ZNT varieties in rice. |
Vol. 21 >B. Research Notes>III. Genetics of physiological traits and others |