Ovule number as a rising star for regulating seed yield: Hope or hype

Rapeseed (Brassica napus L.) is the second most premium oilseed crop, mainly grown for vegetable oil and protein meal around the globe. One of the main goals for breeders is to produce high-yield rapeseed cultivars with sustainable production to meet the requirements of the fast-growing population. Besides the pod number, seeds per silique (SS), and thousand-seed weight (TSW), ovule number (ON) is the decisive yield determining factor of a single plant and final seed yield. In recent years, tremendous efforts have been made to dissect the genetic and molecular basis of these complex traits. Still, only relatively few genes or loci controlling these traits have been reported. This review highlighted the updated hormonal and molecular basis of ON and development in model plants (A. thaliana). This review also compiled efforts at the hormonal, molecular, and genetic mechanism of ovule development and number and bridge the understanding between the model plant species (A. thaliana) and cultivated species (B. napus). This report will open a new corridor for primary and applied research in plant biology and benefit rapeseed breeding programs. This literature will inculcate research interest to understand further ovule number determination, its role in yield improvement, and possible utilization in breeding programs.