Location: Crops Pathology and Genetics Research
Project Number: 2032-21000-023-11-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jan 1, 2020
End Date: Sep 30, 2021
Research will be conducted on the identification and characterization of rice plants with novel productivity and grain quality traits by screening populations of rice mutants, determining the molecular genetic basis for any novel traits identified in those populations, and developing DNA markers for the transfer of those traits to elite rice cultivars. Specific objectives include: 1) Evaluation of mutant populations and specific mutant lines for herbicide tolerance; 2) Field evaluation and mutant population development; 3) Characterize mutants involved in metalloid element uptake and accumulation.
For objective 1, early generation (M3 or M4) mutants from three populations (Nipponbare, Kitaake, and Sabine) will be screened for altered responses to various herbicides. These screens will be performed in conjunction with the evaluation of specific rice mutants identified by TILLING (reverse genetics) of herbicide target genes encoding protoporphyrinogen oxidase, 4-hydrophenyl pyruvate dioxygenase, acetyl Co-A carboxylase, glutamine synthetase (chromosome 2), and glutamine synthetase (chromosome 10). Screening will be conducted on a greenhouse scale with the use of a specially designed cabinet sprayer. Plants will be grown in the greenhouse and seedlings of the appropriate developmental stage will be treated with herbicide based on dose response pilot experiments which will be conducted for each herbicide employed and will involve the wild type progenitor varieties (i.e. Nipponbare, Kitaake, and Sabine). Candidate tolerant/resistant mutant lines will be re-tested to confirm initial evaluation results and planted in the greenhouse for seed and genetic crosses. In objective 2, the most advanced generation of each of three mutant populations will be used (M3 for Nipponbare, M8 for Kitaake, and M4 for Sabine). Five hundred lines from each population (single rows, 10 feet long with 1 ft. spacing between rows and 2-3 ft. spacing/alleys between row tiers) will be planted in the UC Davis rice field facility and preliminary evaluation of agronomic performance related traits will be conducted. Planting may be performed by direct dry seeding or by transplanting using a paper pot system. Lines will be evaluated for various agronomic performance traits (i.e., height, tillering, heading date, and panicle traits) and seeds will be harvested to serve as a long-term seed source for trait evaluation including further generation advance and field testing. For objective 3, mutant lines identified from analyses performed in 2019 will be subjected to crossing and additional phenotyping experiments (e.g. evaluation for disease and other stress tolerance). Primarily, backcrossing of mutants to the wild type Nipponbare will be performed to eliminate background mutations which may be affecting the full expression of the mutant trait. Additional crosses between lsi1 and lsi2 and NM-4903 (Osabcc1) to both lsi1 and lsi2 mutants will be attempted in 2020 based on the lines identified in 2019. The lsi1 and Osabcc1 mutants not previously evaluated will be planted in the greenhouse for small-scale evaluation of silicon and arsenic content. Elemental analysis will be performed by the UC Davis Analytical Lab or the UC Davis ICP-MS facility.