Lack of Tocopherol Inhibits Rice Growth by Triggering an Ectopic Stress Response and the Accumulation of DELLA Protein

摘要

Although tocopherols are essential for rice development,the molecular details by which their absence affects development remain to be determined.To study how tocopherols function during rice development,we performed a transcriptome deep sequencing(RNA-seq)analysis of the rice cultivar Nipponbare(Nip)and the tocopherol-deficient mutant small grain and dwarf 1-2(sgd1-2).We identified 563 differentially expressed genes that were enriched in Gene Ontology categories associated with metabolism,stress,cellular responses,and transcriptional regulation.We determined that the total fatty acid composition of Nip and sgd1-2 was comparable,although cell membrane penetrability in sgd1-2 was significantly higher than in Nip under optimal growth conditions,indicating that tocopherol deficiency induces cell membrane damage.The expression levels of dehydration-responsive element binding 1(DREB1)genes and free proline content in sgd1-2 were also higher than those in Nip.We also showed that the DELLA protein SLENDER RICE1(SLR1)accumulated in sgd1-2,resulting in significant changes in the global transcriptome.Our study confirms that the lack of tocopherol accumulation in rice induced ectopic stress responses and limited growth by enhancing SLR1 abundance through increasing SLR1 transcript levels.These results provide new insights into tocopherol during rice development.