Production of yellow‐seeded Brassica napus through interspecific crosses

Abstract

AbstractYellow‐seeded Brassica napus was developed from interspecific crosses between yellow‐seeded Brassica rapa var.‘yellow sarson’ (AA), black‐seeded Brassica alboglabra (CC), yellow‐seeded Brassica carinata (Bbcc) and black‐seeded B. napus (AACC). Three different interspecific crossing approaches were undertaken. Approaches 1 and 2 were designed directly to develop yellow‐seeded B. napus while approach 3 was designed to produce a yellow‐seeded CC genome species. Approaches 1 and 2 differed in the steps taken after trigenomic interspecific hybrids (ABC) were generated from B. carinata×B. rapa crosses. The aim of approach 1 was to transfer the yellow seed colour genes from the A to the C genome as an intermediate step in developing yellow‐seeded B. napus. For this purpose, the ABC hybrids were crossed with black‐seeded B. napus and the three‐way interspecific hybrids were self‐pollinated for a number of generations. The F7 generation resulted in the yellowish‐brown‐seeded B. napus line, No. 06. Crossing this line with the B. napus line No. 01, resynthesized from a black‐seeded B. alboglabra x B. rapa var.‘yellow sarson’ cross (containing the yellow seed colour genes in its AA genome), yielded yellow‐seeded B. napus. This result indicated that the yellow seed colour genes were transferred from the A to the C genome in the yellowish‐brown seed colour line No. 06. In approach 2, trigenomic diploids (AABBCC) were generated from the above‐mentioned trigenomic haploids (ABC). The seed colour of the trigenomic diploid was brown, in contrast to the yellow seed colour of the parental species. Trigenomic diploids were crossed with the resynthesized B. napus line No. 01 to eliminate the B genome chromosomes, and to develop yellow‐seeded B. napus with the AA genome of ‘yellow sarson’ and the CC genome of B. carinata with yellow seed colour genes. This interspecific cross failed to generate any yellow‐seeded B. napus. Approach 3 was to develop yellow‐seeded CC genome species from B. alboglabra×B. carinata crosses. It was possible to obtain a yellowish‐brown seeded B. alboglabra, but crossing this B. alboglabra with B. rapa var.‘yellow sarson’ failed to produce yellow seed in the resynthesized B. napus. The results of approaches 2 and 3 demonstrated that yellow‐seeded B. napus cannot be developed by combining the yellow seed colour genes of the CC genome of yellow‐seeded B. carinata and the AA genome of ‘yellow sarson’.