Global climate change seriously threatens food security. To address this challenge, breeders have achieved remarkable results using multiple breeding strategies and technologies. In recent years, the application of biomolecular condensates to crop improvement has remained in its early stages. Nevertheless, growing evidence indicates their crucial roles in regulating crop development and stress adaptation. This review synthesizes recent advances in understanding biomolecular condensate functions across key plant developmental phases and their regulatory roles in abiotic and biotic stress responses. The regulatory mechanisms associated with these condensates primarily encompass transcriptional regulation, RNA processing and metabolism, translational control, and membrane organelle biogenesis, collectively establishing a solid theoretical foundation for agricultural molecular breeding. In the final section, we discuss the potential applications and challenges of biomolecular condensates in crop improvement.

In four rice genomes, 85 ABC1-family genes were identified by comparative genomics, evolution, genetics, and physiology. One, OsABC1-13, was shown by knockdown and knockout experiments to affect plant height, grain size, and photosynthetic capability.

Grain size, characterized by a combination of grain length, width, and thickness, is one of the major determinants of yield in rice. The present study identified TATA-box binding protein-associated factor 2 (TAF2) as an essential component regulating transcription and determining grain size in rice. Map-based cloning showed that a G/T substitution in TAF2 resulted in a naturally occurring mutant called reduced grain size and plant height 1 (rgh1). The mutants, with weak edited rgh1 alleles, exhibited a small grain phenotype with reduced grain length and width, while the severe knockout mutant (rgh1-2s) was dwarf and completely sterile. Allelic test performed between rgh1 and several edited alleles confirmed that the mutation in TAF2 caused the rgh1 phenotype. GUS staining showed that TAF2 was mainly expressed in the vascular bundles of roots, stems, leaves, and grains. The cytological analysis revealed that reduced cell division in the glumes resulted in the small grain phenotype of rgh1. Further RNA-sequencing detected altered expression of genes involved in the basic biological processes in rgh1 mutant. These findings provide novel insights into the TAF2-mediated genetic mechanism regulating grain size in rice.

Rice (Oryza sativa L.) is a major food crop worldwide. Plant height and yield are important agronomic traits of rice. Several genes regulating plant height and/or yield have been cloned. However, the molecular mechanisms coordinating plant height and yield are not fully characterized. Here, we report a novel gene, OstMAPKKK5 that encodes a truncated variant of a mitogen-activated protein kinase kinase kinase 5 (OsMAPKKK5) lacking an intact kinase domain. Transgenic plants overexpressing OstMAPKKK5 in indica cultivar 9311 showed increased plant height, grain length, grain width, 1000-grain weight, grain number per main panicle, and yield. Real-time quantitative PCR showed that OstMAPKKK5 was widely expressed in various tissues and developmental stages. The increased plant height and yield were attributed to enlarged cell size. Overexpression of OstMAPKKK5 led to higher contents of various forms of endogenous gibberellin (GA), especially the most common active forms, GA₁, GA₃, GA₄. We concluded that OstMAPKKK5 positively regulates plant height and yield in rice by affecting cell size, and that its underlying mechanism is based on increased endogenous GA content.