Abstract
Rice is one of the major staple cereals in the world, but heat stress is increasingly threatening its yield. Analyzing the thermotolerance mechanism from new thermotolerant germplasms is very important for rice improvement. Here, physiological and transcriptome analyses were used to characterize the difference between two germplasms, heat-sensitive MH101 and heat-tolerant SDWG005. Two genotypes exhibited diverse heat responses in pollen viability, pollination characteristics, and antioxidant enzymatic activity in leaves and spikelets. Through cluster analysis, the global transcriptomic changes indicated that the ability of SDWG005 to maintain a steady-state balance of metabolic processes played an important role in thermotolerance. After analyses of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, we found that the thermotolerance mechanism in SDWG00 was associated with reprogramming the cellular activities, such as response to abiotic stress and metabolic reorganization. In contrast, the down-regulated genes in MH101 that appeared to be involved in DNA replication and DNA repair proofreading, could cause serious injury to reproductive development when exposed to high temperature during meiosis. Furthermore, we identified 77 and 11 differentially expressed genes (DEGs) involved in lignin and flavonoids biosynthetic pathways, respectively. Moreover, we found that more lignin deposition and flavonoids accumulation happened in SDWG005 than in MH101 under heat stress. The results indicated that lignin and flavonoid biosynthetic pathways might play important roles in rice heat resistance during meiosis.
Highlights
With an increase in the frequency and intensity of extreme heat waves, high-temperature stress has become one of the severe limiting factors affecting crop production and distribution worldwide (Lobell and Gourdji, 2012; Wang et al, 2016; Yang et al, 2017)
The results showed that heat stress at the meiosis stage significantly affected pollen viability and pollination properties in rice plants, and the extent of the viability reduction and deficient pollination were dependent on the genotypes and temperature (Figure 1)
The percentage of basal dehiscent anthers was measured in the flowers of SDWG005 and MH101 plants at anthesis, and the results showed that heat stress significantly reduced the rate of basal anther dehiscence in the two genotypes (Figure 1C)
Summary
With an increase in the frequency and intensity of extreme heat waves, high-temperature stress has become one of the severe limiting factors affecting crop production and distribution worldwide (Lobell and Gourdji, 2012; Wang et al, 2016; Yang et al, 2017). Of all the reproductive processes, the most susceptible stages to heat stress were flowering and microspore meiosis (Satake and Yoshida, 1978; Jagadish et al, 2007). Rice pollen abortion and floret sterility were relatively less susceptible to high temperature at the meiosis stage (Matsui et al, 2000; Jagadish et al, 2010, 2014; Shah et al, 2011). Male sterility induced by high temperature appears to be associated with the poor pollen development (Matsui et al, 2000; Ku et al, 2003). Many physiological studies have contributed to our understanding of heat-induced pollen fertility injury, molecular analyses are still largely lacking
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
