AUTHOR=Begcy Kevin , Sandhu Jaspreet , Walia Harkamal 

TITLE=Transient Heat Stress During Early Seed Development Primes Germination and Seedling Establishment in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 9 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01768

DOI=10.3389/fpls.2018.01768

ISSN=1664-462X

ABSTRACT=Rice yield is highly sensitive to increased temperature. Given the trend of increasing global temperatures, this sensitivity to higher temperatures poses a challenge for achieving global food security. Early seed development in rice is highly sensitive to unfavorable environmental conditions. Heat stress during this stage decreases seed size and fertility, thus reducing yield. Here, we explored the transgenerational phenotypic consequences of heat stress during early seed development on seed viability, germination, and establishment. To elucidate the impact of heat stress on the developmental events in post-zygotic rice seeds, we imposed moderate (35°C) and severe (39°C) heat stress treatments initiated one day after fertilization and maintained for 24, 48 or 72 h. The transient heat stress treatments altered the initiation of endosperm cellularization, seed size and/or the duration of spikelet ripening. Notably, seeds exposed to 24 and 48 h moderate heat stress exhibited higher germination rate compared to seeds derived from plants grown under control or severe heat stress. A short-term heat stress resulted in altered expression of GA and ABA biosynthesis genes during early seed development, and GA and ABA levels and starch content at maturity. The increased germination rate after 24 of moderate heat stress could be due to altered ABA sensitivity and/or increased starch level. Our findings on the impact of transient heat stress on hormone homeostasis provide an experimental framework to elucidate the underlying molecular and metabolic pathways.