Project Number: 6225-21220-005-00
Start Date: Jul 10, 2013
End Date: Jul 09, 2018
Wild rice accessions will be evaluated for blast disease resistance and sources with novel genes will be used in a backcrossing program to both map the novel QTL and develop germplasm with improved resistance. A major gene that provides resistance to a blast race that is virulent on all sources of resistance commonly used in the USA will be finely mapped. Closely linked DNA markers will be used for its introgression using marker assisted selection into improved germplasm for use by breeders. The interaction and evolutionary dynamics of genes involved in blast resistance in both rice and the pathogen will be examined. The genetic identity of contemporary and historical field isolates will be determined using genomic techniques and international differentials. Small differences in resistance response to sheath blight disease will be evaluated and used to identify the location of quantitative resistance QTL. Newly introduced wild accessions of rice and diverse global cultivars will be evaluated for novel sheath blight resistance alleles which will be incorporated to US germplasm for use by breeders. A major sheath blight resistant QTL will be finely mapped so that DNA markers and improved germplasm can be developed. Rice root imaging, plant growth patterns, early tillering, and allelopathic activity associated with weed suppression will be determined and used in mapping studies. Weed suppression traits effective under reduced-irrigation systems or reduced-pesticide/organic systems will be characterized. Cold temperature tolerance at the seedling stage and high temperature stress at the flowering stage will be assessed using diversity panels and mapping populations. A greenhouse study will be conducted using rice cultivars demonstrated to differ in methane emissions under field conditions to determine plant traits that may explain these differences. Best nitrogen fertilizer management practices for minimizing greenhouse gas emissions will be identified using intermittent flood and genetic resources previously shown to differ in methane emissions. The key components including best cultural management techniques and agronomic and phenological traits associated with greenhouse gas reduction relevant to southern US germplasm will be identified. Genetic markers that are linked to key phenotypic traits associated with productivity under intermittent flood will be identified for ultimately developing cultivars that can be grown under reduced water use. Genetic resources and markers that demonstrate genetic differences for salinity tolerance at the seedling stage will be identified to develop improved germplasm and cultivars for US rice production. The outcome of this research will result in genetic markers linked to traits that can be incorporated into new cultivars that are resilient to disease, weed pressure, salinity, extremes in temperatue, and can be grown under production practices that use less water and have reduced greenhouse gas emissions.