Fig. 6. Schematic representation of conventional breeding and the designed NPBT for trait improvement.

(A) Pathway for breeding of recessive traits using a wild relative or mutagenized plant as parent material. Multiple crosses are required to introgress a homozygous mutation into a farmer-preferred genotype. Several years are required to generate an improved variety. ^†Information about mutation and availability of genetic marker(s) could allow bypassing of the selfing step. ^‡In the absence of marker(s), self-crosses are performed after every backcross to select offspring with the recessive trait phenotype. ^ΔAvoiding selfing should limit potential inbreeding depression. (B) NPBT described here for accelerated flowering and segregation of genome-edited lines. Agrobacterium-mediated stable transformation provides transgenic lines with different mutant populations. Several lines are screened (phenotype and genotype), and a single segregation from selfing or cross between two Cas9-FT–transformed genotypes can occur ex situ in a glasshouse environment, yielding T-DNA–free progeny with the homozygous recessive mutation.