Screening Diverse Weedy Rice (Oryza sativa ssp.) Mini Germplasm for Tolerance to Heat and Complete Submergence Stress During Seedling Stage

Shandrea Stallworth,Te-Ming Tseng,Brooklyn Schumaker,Nilda Roma-Burgos,Swati Shrestha

doi:10.3389/fagro.2021.642335

Shandrea Stallworth, Te-Ming Tseng + Show 3 more

Open Access

https://doi.org/10.3389/fagro.2021.642335

Copy DOI

Abstract

Rice is a staple food for more than 3.5 billion people worldwide, with Asia producing almost 90% of the global rice yield. In the US, rice is primarily produced in four regions: Arkansas Grand Prairie, Mississippi Delta, Gulf Coast, and Sacramento Valley of California. Arkansas currently accounts for more than 50% of the rice produced in the US. As global temperatures continue to rise and fluctuate, crop-breeding programs must continue to evolve. Unfortunately, sudden submergence due to climate change and unpredictable flash flooding can cause yield reduction up to 100% and affect 20 million ha of agricultural farmlands. Similarly, it has been demonstrated that temperatures higher than 34°C can cause spikelet infertility resulting in up to 60% reduction in yield. One major drawback to developing abiotic stress-tolerant rice is the loss of critical traits such as vegetative vigor, spikelet fertility, and grain quality, which are essential in increasing economic return for farmers. To replace traits lost in past breeding endeavors, weedy rice (WR) has been proposed as a source for novel trait discovery to improve rice breeding programs. Therefore, the goal of this study was to screen and identify heat- and submergence-tolerant WR accessions. A WR mini germplasm consisting of seedlings at the 3–4 leaf stage was exposed to heat (38°C) and complete submergence for 21 days. After each treatment, height was recorded every 7 days for 28 days, and biomass was collected 28 days after treatment. The average height reduction across all accessions was 19 and 21% at 14 and 28 days after treatment (DAT) for the heat-stress treatment. The average height reduction across all accessions was 25 and 33% for the complete submergence stress. The average biomass reduction across all accessions was 18 and 21% for heat and complete submergence stress, respectively. Morphologically, at 28 DAT, 28% of the surviving WR accessions in the heat-stress treatment with &lt;20% height reduction were straw-colored hull types without awns. Under complete submergence stress, 33% of the surviving WR accessions were blackhull types without awns. These specific biotypes may play a role in the increased resilience of WR populations to heat or submergence stress. The results presented in this paper will highlight elite WR accessions that can survive the effects of climate change.

Highlights

Rice, Oryza sativa, is a major food staple and arguably one of the most essential crops feeding close to half of the world’s population and providing more than 50% of the daily calories (Muthayya et al, 2014; Kim et al, 2015; Dong and Xiao, 2016)
In the US, rice yields continue to increase annually due to the adoption of optimum management practices and the introduction and adoption of hybrid rice varieties, but rice production systems still struggle against increased weed pressure and impacts of climate change (Espe et al, 2016; Fargione et al, 2018)
This study aimed to identify heat- and submergence-tolerant weedy rice (WR) accessions and characterize the competitive traits of stresstolerant accessions

Summary

Introduction

Oryza sativa, is a major food staple and arguably one of the most essential crops feeding close to half of the world’s population and providing more than 50% of the daily calories (Muthayya et al, 2014; Kim et al, 2015; Dong and Xiao, 2016). Of the significant abiotic stresses, rice can be impacted by salinity, drought, flooding, and high/low temperatures (Hasanuzzaman et al, 2018) In crops such as maize, soybeans, and rice, climate extremes explain 18–43% of the yield variance from year to year (Vogel et al, 2019). Temperatures above 33◦C can negatively impact all stages of plant growth and development with temperatures above 37◦C causing a complete loss of plants at the reproductive stage (Jagadish et al, 2007; Aghamolki et al, 2014; Kilasi et al, 2018) Temperatures above this threshold are typical in the summer months in the southern US, but US rice is able to withstand these temperatures notwithstanding some yield losses (Tenorio et al, 2013; Chiang et al, 2018)

Objectives

Methods

Results