Divergent phenotypic response of rice accessions to transient heat stress during early seed development

Authors

Puneet Paul, University of Nebraska-LincolnFollow
Balpreet K. Dhatt, University of Nebraska-Lincoln
Jaspreet Sandhu, University of Nebraska-LincolnFollow
Waseem Hussain, University of Nebraska-Lincoln & International Rice Research Institute
Larissa Irvin, University of Nebraska-Lincoln
Gota Morota, Virginia Polytechnic Institute and State University
Paul E. Staswick, University of Nebraska - LincolnFollow
Harkamal Walia, University of Nebraska-LincolnFollow

Date of this Version

12-19-2019

Citation

2020 The Authors

Comments

DOI: 10.1002/pld3.196 Plant Direct. 2020;4:1–13. wileyonlinelibrary.com/journal/pld3

Abstract

Increasing global surface temperatures is posing a major food security challenge. Part of the solution to address this problem is to improve crop heat resilience, especially during grain development, along with agronomic decisions such as shift in planting time and increasing crop diversification. Rice is a major food crop consumed by more than 3 billion people. For rice, thermal sensitivity of reproductive development and grain filling is well-documented, while knowledge concerning the impact of heat stress (HS) on early seed development is limited. Here, we aim to study the phenotypic variation in a set of diverse rice accessions for elucidating the HS response during early seed development. To explore the variation in HS sensitivity, we investigated aus (1), indica (2), temperate japonica (2), and tropical japonica (4) accessions for their HS (39/35°C) response during early seed development that accounts for transition of endosperm from syncytial to cellularization, which broadly corresponds to 24 and 96 hr after fertilization (HAF), respectively, in rice. The two indica and one of the tropical japonica accessions exhibited severe heat sensitivity with increased seed abortion; three tropical japonicas and an aus accession showed moderate heat tolerance, while temperate japonicas exhibited strong heat tolerance. The accessions exhibiting extreme heat sensitivity maintain seed size at the expense of number of fully developed mature seeds, while the accessions showing relative resilience to the transient HS maintained number of fully developed seeds but compromised on seed size, especially seed length. Further, histochemical analysis revealed that all the tested accessions have delayed endosperm cellularization upon exposure to the transient HS by 96 HAF; however, the rate of cellularization was different among the accessions. These findings were further corroborated by upregulation of cellularization associated marker genes in the developing seeds from the heat-stressed samples.