Molecular Breeding for Phosphorus-efficient Rice - Translational Genomics for Crop Breeding: Abiotic Stress, Yield and Quality - page 65

Chapter 5

Molecular Breeding for
Phosphorus-efficient Rice

SigridHeuer,J.H.Chin,R.Gamuyao,S.M.Haefele,and M.Wissuwa

Abstract

Rice is the main staple food for more than half of the world's population and the main source of
calories in most Asian and many African countries. Since many rice-dependent countries are poor,
it is critically important to keep rice prices low and increase productivity to provide sufficient food
for a growing population. However, a sustainable increase in rice production is possible only if
nutrients removed with the harvest are replaced by application of either mineral fertilizers or manure.
Since fertilizer costs are rising, depletion of soil nutrients is an increasing problem, especially in the
developing world where most farmers do not have the resources to purchase sufficient fertilizer or do
not have access to fertilizer. In addition, the majority of rainfed rice in Asia is produced on poor quality
and problem soils that are often low in nutrients or have properties, such as low pH or high aluminum
and iron, that render phosphorus (P) unavailable to plants. On those soils, very high fertilizer doses
have to be applied to provide sufficient plant-available P. Given that currently known rock phosphate
reserves, the source of P fertilizer, are limited it can be expected that P deficiency will aggravate and
will increasingly limit productivity, especially in poor countries. One way to address this problem is
to develop crops that are more efficient in acquiring P from the soil and applied fertilizer, or crops
with higher internal P-use efficiency, that is, with higher biomass production per unit P.
In this paper, we provide a brief comprehensive overview on P-related aspects of rice production
and highlight the potential of molecular breeding approaches to improve P-efficiency. As an example,
we describe the major quantitative trait locus Phosphorus uptake 1 ( Pup1 ), which confers tolerance
of P deficiency.

insufficient plant-available P constrains plant
growth on more than 5.7 billion ha of land world-
wide (Batjes 1997). According to a more recent
study, more than 50% of global agricultural land
is deficient in P (Lynch 2011). A study on P

Introduction

Phosphorus (P) is an essential macro-element for
all living cells and therefore crucially important
for crop production. It has been estimated that