CRISPR-driven innovations in rice (Oryza sativa L.) breeding: precision development of male sterile lines

Male sterility is a vital trait exploited in hybrid seed production to boost crop yield and improve quality. In rice, different male sterility systems have been developed, significantly advancing the production of high-yielding hybrids. The three main types of male sterility in rice are cytoplasmic male sterility (CMS), photoperiod-sensitive genic male sterility (PGMS), and genic male sterility (GMS). Among these, CMS is the most widely used, arising from interactions between mitochondrial (cytoplasmic) and nuclear genes, resulting in pollen dysfunction. PGMS, on the other hand, is influenced by environmental cues such as day length and temperature, while GMS is attributed to mutations in specific nuclear genes affecting anther or pollen development. A thorough understanding of the genetic and molecular mechanisms underlying these systems is essential for efficient hybrid rice breeding. CMS lines are typically crossed with maintainer and restorer lines carrying fertility-restoring genes to produce fertile F₁ hybrids. Recent advancements in molecular biology, genomics, and genome editing technologies have accelerated the development of novel male-sterile and fertility-restoring lines, thereby enhancing the precision and scalability of hybrid breeding programs. These innovations are not only expanding the genetic base of hybrid rice but also making the production process more sustainable. As global food demand rises alongside climate uncertainties, the strategic use of male sterility in rice breeding holds immense potential for improving agricultural productivity.