Higher plants usually start from seed germination and re-form seeds after vegetative growth and reproductive development, thus completing the life cycle. Carbohydrates, lipids, proteins, mRNA and other macromolecular substances accumulated in seeds are crucial to maintain the germination potential of seeds, some of which can be preserved for a long time without degradation, known as long-lived mRNA. In rice, long-lived mRNA associated with germination began to be transcribed and accumulated 10 to 20 days after flowering, and some long-lived mRNA associated with dormancy and stress response were transcribed and preserved in cells from 20 days after flowering to seed maturity. There are many kinds of long-lived mRNA, mainly including some protein synthesis mRNA, energy metabolism mRNA, cytoskeleton mRNA and some stress response related mRNA, such as small heat shock protein, LEA (late embryogenesis abundant) family proteins. Transcriptome analysis found that the promoter regions of many genes contain ABA- or GA-associated cis-acting elements, and there are about 500 differentially expressed long-lived mRNAs in the Arabidopsis atabi5 (ABA-insensitive 5) mutant seeds that differ from the wild type, suggestting that abscisic acid (ABA) and gibberellin (GA) are the key hormones that influence the type of long-lived mRNA. Long-lived mRNAs are usually cross-linked with a single ribosome, RNA binding protein, and exists in cells in the form of P-bodies (PBs) to protect the mRNA from degradation. However, long-lived mRNAs associated with seed dormancy are gradually degraded during seed post-ripening, and the oxidative modification of some specific long-lived mRNAs is also a biological phenomenon to break seed dormancy. During the long-term storage of seeds, the random degradation of long-lived mRNA is directly related to the life and vitality of seeds, and the retained mRNA is translated into protein to help the rapid germination of seeds in the early stage of imbibition. In this paper, the characteristics and functions of long-lived mRNA were reviewed, and some scientific issues were raised in order to provide a reference for further understanding of the molecular mechanisms of seed dormancy, germination and longevity.

As one of the key factors affecting rice yield, the grain number per panicle has always attracted the attention of breeders. The formation of grain number per panicle is a complex biological process, which is regulated by many genes. According to their impact on phenotype, we roughly divide these genes into three categories: related to the number of branches, related to panicle type and related to spikelet determination. In this paper, we summarized the genetic regulation mechanisms of the grain number per panicle-related genes, and put forth the strategies for their use in high yield breeding of rice.

Systemic acquired resistance (SAR) is a long-lasting broad-spectrum resistance at the whole plant level activated by the primary infection of pathogenic microorganisms at local leaves. The signals generated rapidly at the initial infection site can be transmitted to other parts of the plant through the phloem to activate SAR. Pipecolic acid (Pip) and N-hydroxy-pipecolic acid (NHP), as newly discovered mobile signal molecules, play important roles in SAR signaling pathway. Here, we mainly review the latest research progress in the synthesis, transportation of Pip/NHP and their regulation of SAR.