Project Accomplishments and Outcomes

1. Rice cultivars are most sensitive to heat stress at R2 through R5 reproductive phases that represent booting to anthesis stages. While daytime temperature was found to have greater effect on yield components, the nighttime temperatures was found to control chalkiness, a major quality trait defined by opaque areas in the grain that is associated with low marketability and low milled rice yields in US rice industry.

2.  Pattern of starch granules (small and round vs large and edged) determines % chalk in rice grains. This pattern is genotype-dependent and correlates with the expression pattern of starch synthesis genes, ADP-Glucose Phosphorylase Large Subunit 4, Starch Synthase IIA, and Granule Bound Starch Synthase I. Break in the temporal coordination in these genes under HNT condition leads to round granules that generate high % chalk.

3.  The gene regulatory network of rice, developed using publicly available datasets in NCBI, was probed with genes that differentially express in response to HNT. The predicted regulators of the perturbed starch genes mainly belong to the NAC and CCAAT gene families. The DNA-binding sites of a few predicted regulators are over-represented within the 1000 bp promoter regions of starch synthesis genes. Changes in the expression of these candidate regulators could be associated with the break in temporal coordination of their target starch synthesis genes.

Significant continued progress was made on four-research objectives including 3 focus areas: a) Phenomics of the japonica diversity panel (JDP) and the bi-parental mapping population for rice grain yield and quality; b) omics of HNT response in Arkansas rice cultivars and diverse rice accessions, and c) biotechnology of US rice cultivars. The research activities are on schedule, with several of new activities described in the section below. The major accomplishments of the research efforts are:

1. Greenhouse screening and phenotypic evaluation of 286 accessions of the JDP for yield components & grain quality, and the 200 bi-parental RIL mapping population of Cypress and LaGrue for grain quality traits under control and HNT conditions. Starch content (amylose content and chain distribution) was analyzed in the representative HNT-tolerant and HNT-sensitive 13 genotypes including US rice cultivars (Pereira Lab, UAF and Dr. Ya-Jane Wang, UAF– https://food-science.uark.edu/people/faculty/uid/yjwang/name/Ya-Jane+Wang/).

2. Genetic dissection of the URMC for grain yield components and quality traits under HNT stress using GWAS and identification of SNP markers (Pereira Lab, UAF).

3. Development of ‘omics’ datasets (mRNA, small RNA, metabolome) of the 13 representative HNT- tolerant and HNT-sensitive US rice cultivars and other accessions (UAF, OSU, UALR, LSU).

4. Testing new strategies to enhance transformation efficiency and design the transformation experiments (Srivastava Lab, UAF and Pereira Lab, UAF).

A. Research Outcomes:

1. Generation of 13 phenomics and genomics datasets for deciphering ‘genome to phenome’ links in diverse rice genotypes.

2. Publications and Patents – The project led to 22 peer-reviewed publications (https://rice-hnt-stress.uark.edu/publications/) and one patent to PI Pereira on heat stress tolerance in rice.

3. Newly awarded grants:

i) PI Pereira – Arkansas Rice Research and Promotion Board grant ($55,000; 7/15/2020 – 6/30/2022), Vice-Chancellor’s award on Disease resistance and HNT

ii) Co-PI Khodakovskaya – USDA-NIFA grant ($474,578; 01/01/2021 – 01/01/2024)

iii) Co-PI Famoso – USDA-NIFA, Louisiana Rice Research Board and U.S. rice industries ($1.23 million)

iv) Co-PI Srivastava – ABI Division of Agriculture ($50,000; 2020-2021).

B. Jurisdictional impacts (JI) for all involved jurisdictions resulted in providing K-12/undergraduate/graduate/ students and post-docs with intellectual, technical and educational opportunities including guidance on career development.

C. Interjurisdictional Collaborations (IJC) between the four participating institutions.

D. Project Integrations were initiated by Dr. Pereira, UAF and Dr. Srivastava, UAF through newly funded Minority Serving Institute (MSI) collaborations as supplemental grants (https://rice-hnt-stress.uark.edu/msi-collaborators/).

E. Workforce Development (WFD) resulted in a diverse group of 66 researchers from the four participating institutions contributed to the project activities.

F. Development or Recruitment of Diverse Early Career Faculty that supported early career faculty (Dr. Brijesh Angira, LSU; Dr. Ellie Nguyen, OSU; Dr. Scott Woolbright, UALR) in career enhancement.

The project fostered collaborations between the participating institutions as well as within each institution, providing training for students, including minority students, postdocs, and offering research opportunities and professional development to the early-career faculty. Infrastructure enhancement of metabolomics equipment (UALR) brought in much-needed data on HNT-perturbed metabolome in rice. Facilitation of broader participation of researchers from the Rice Research and Extension Center (RREC) at Stuttgart, AR led to data sharing and integration, and a joint publication. Infrastructure development, broadening participation, and the training of young scientists led to the development of research capabilities at both jurisdictional and inter-jurisdiction levels.