Malay Saha, Ph.D.
Drought is the single most important constraint to crop productivity. Severe water limitations, especially for agricultural use, have been observed in many areas of the world. According to various prediction models, the scenario is likely to get worse due to increase in aridity. The persistence of perennial grasses largely depends on their ability to tolerate drought and heat stresses. Tall fescue is an important cool-season perennial hay and pasture grass grown on 14 million hectacres (about 34.6 million acres) in the United States. Despite being perennial, the Continental (summer active) tall fescue cultivars usually do not persist beyond two to four years in the south central U.S. because of hot and dry summers. On average, 40 percent to 60 percent stand loss/year of tall fescue was observed in the region. However, 100 percent stand loss of the crop can also be encountered after a harsh summer like 2011 and 2012. Persistence can be improved through introduction of drought tolerance in Continental and summer dormancy in Mediterranean tall fescue morphotypes. The development and release of drought tolerant and summer dormant tall fescue cultivars would benefit livestock farmers in this region.
Simple, reliable and repeatable phenotyping procedures of stress tolerance can facilitate rapid screening of large numbers of germplasms to identify superior genotypes. A screening protocol has been developed to simultaneously evaluate root and shoot traits under drought stress. Germplasm resources from GRIN and breeding populations were screened. Genotypes from both ends of drought response distribution have been selected. Field evaluation of the selected genotypes is ongoing. Genotypes with enhanced drought tolerance will be used to develop synthetic populations. Selection cycles will be continued to increase the frequency of favorable alleles in breeding populations. A mapping population developed by crossing drought tolerant and susceptible genotypes has been genotyped following the genotyping by sequencing protocol. Greenhouse evaluation of the population has been accomplished. Field evaluation of the same population is in progress. Morphological and physiological study related to water use efficiency and drought tolerance have been performed. The genotypic and phenotypic data will be used to identify genetic loci associate with drought related traits. Transcriptome studies are underway to identify genes and genetic mechanisms that contribute to drought tolerance. Validation of key gene targets using qRT-PCR and VIGS protocols is ongoing. Metabolomics profiling of genotypes with contrasting drought tolerant characteristics is in progress. Similar strategies have been undertaken for the improvement of summer dormancy in Mediterranean tall fescue.
- Improving water use efficiency, drought tolerance and persistence of tall fescue
- Deciphering summer dormancy in tall fescue
- Marker-assisted breeding for improving forage digestibility in tall fescue
- Identification of N use efficient bermudagrass and wheat plants from natural populations
- GWAS studies to identify QTL and molecular markers associated with nitrogen use efficiency (NUE) and related traits in bermudagrass
- Detect genetic loci and/or genes associated with important traits in switchgrass
- Establishment to senescence: plant-microbe and microbe-microbe interactions mediate switchgrass sustainability