Stagnating productivity of irrigated rice (Oryza sativa) over the past decade has seen the rate of increase in production fall below the rate of population increases. This creates concerns for medium to long-term food security. Throughout Asia rice is the staple crop food, with more than 90 per cent of all rice grown in the region and 50 per cent of dietary calories coming from rice consumption. Hybrid rice, incorporating two or more differing rice lines with traits from both parents, has been shown to provide yield boosts. In China the introduction of hybrid rice accounted for a one-off yield increase of around 30 per cent in production per hectare. Other Asian countries are hoping to use hybrids to reproduce this boost. Most hybrid varieties are intrasubspecific (for instance two lines from the same type - indica/indica). It is expected that these hybrids will be superseded by intersubspecific hybrids that offer greater advantages through combining two lines of different types with a combined traits of both parents.
Making high-yielding hybrid varieties available to the poor may be helped by one-line or apomictic production. This is potentially cheaper and more flexible than multi-line hybrids while still offering the same advantages. One line hybrids reproduce asexually through apomixis (fertilisation of the egg by non-sexual means). In rice this process is possible through synthetic activation of apomixis. Achieving this in single line hybrids would be cheaper and more likely to ensure equal yields than in multil-line hybrids. Through this project research will address key issues in developing apomictic rice, focusing on the role of fertilisation independent genes in other plants for their application to hybrid rice.
Fertilization-independent (FI) formation of rice endosperm and pericarp
Analysis of role of rice OsAsp1 gene in FI pericarp formation
Transformation of rice with RNAi constructs for OsFIS genes
Crossing lines to achieve FI formation of both pericarp and endosperm
FI embryogenesis in rice nucellus
Isolation of OsMac1 and expression analysis
Isolation of rice CLV, WUS, STM, AG genes and expression analysis
Identification of suitable activator/receptor/target system to allow MMC1 to control gene expression in nucellar neighbours
Induction of MMC2 by RNAi of OsMac1
Induction of embryo in MMC2
Induction of embryo in nucellar neighbours of MMC1
Apomictic hybrid rice
Crossing of plants containing FI pericarp and endosperm with plants containing FI embryo
Determine whether endosperm feeds nucellar embryo during germination
Communication and dissemination of research results
Links:
[1] http://www.aciar.gov.au/country/Philippines
[2] http://www.aciar.gov.au/iarc/International Rice Research Institute
[3] http://www.aciar.gov.au/programarea/Crop Improvement and Management