Reference "Effects of zinc deficiency on rice growth and genetic factors contributing to tolerance"

Reference ID

11377

Title

Effects of zinc deficiency on rice growth and genetic factors contributing to tolerance

Source

Plant physiology, 2006, vol. 142, pp. 731-741

Authors (3)

Wissuwa-M	Ismail-A-M
Yanagihara-S

Abstract

Zinc (Zn) deficiency is the most widespread micronutrient disorder in rice
(Oryza sativa), but efforts to develop cultivars with improved tolerance have
been hampered by insufficient understanding of genetic factors contributing to
tolerance. The objective of this paper was to examine alternative evaluation
methods and to identify the most informative traits that would provide realistic
information for rice breeders and to map quantitative trait loci (QTLs)
associated with tolerance. Screening experiments in low-Zn nutrient solution and
in a Zn-deficient field did not produce similar tolerance rankings in a set of
segregating lines, which suggested that rhizosphere effects were of greater
importance for lowland rice than internal Zn efficiency. The most severe symptom
in the field was high plant mortality. The occurrence of leaf bronzing, usually
regarded as indicative of susceptibility, did not necessarily concur with high
plant mortality, which implied that both were under independent genetic control.
The QTL mapping experiment conducted in the field with a population derived from
a cross of IR74 (intolerant) with Jalmagna (tolerant) largely confirmed this.
Four QTLs associated with plant mortality were detected, and only one of those
colocalized with one of the four QTLs detected for leaf bronzing. The two most
influential QTLs for plant mortality were detected on chromosomes 2 and 12. They
explained 16.6% and 24.2% of the variation, and alleles of the tolerant donor
parent Jalmagna reduced mortality by 16.6% and 14.8%, respectively. QTLs for
plant mortality acted in a purely additive manner, whereas digenic epistatic
interactions were important for leaf bronzing.