Fig. 4.

A four-dimensional profile of precision breeding and crop production system with the concept evolving from point to line, plane and space. Selection in early plant breeding was performed based on single desirable phenotypes one at a time (‘‘point’’). Conventional breeding has been based on selection of multiple phenotypes (‘‘line’’). Marker-assisted breeding uses selection criteria determined by both multiple phenotypes and genotypes (‘‘plane’’). Our future breeding and crop production system will be built upon the knowledge generated by genotyping, phenotyping and envirotyping, which forms the three spatial dimensions (‘‘space’’). Considering the temporal variation across different growth and developmental stages, a fourth dimension (time) should be also included. Green arrows represent the evolutionary steps of plant breeding; gray-dotted arrows represent the selection targets that can be inferred from selection strategies. Revised from Xu et al. (2012)