Interspecific cross of Brassica oleracea var. alboglabra and B. napus: effects of growth condition and silique age on the efficiency of hybrid production, and inheritance of erucic acid in the self-pollinated backcross generation

Abstract

InterspeciWc hybrids were produced from reciprocal crosses between Brassica napus (2n = 38, AACC) and B. oleracea var. alboglabra (2n = 18, CC) to introgress the zero-erucic acid alleles from B. napus into B. oleracea. The ovule culture embryo rescue technique was applied for production of F 1 plants. The eVects of silique age, as measured by days after pollination (DAP), and growth condition (temperature) on the eYciency of this technique was investigated. The greatest numbers of hybrids per pollination were produced under 20°/15°C (day/night) at 16 DAP for B. oleracea ($) £ B. napus crosses, while under 15°/10°C at 14 DAP for B. napus ($) £ B. oleracea crosses. Application of the ovule culture technique also increased the eYciency of BC 1 (F 1 £ B. oleracea) hybrid production by 10-fold over in vivo seed set. The segregation of erucic acid alleles in the selfpollinated backcross generation, i.e. in BC 1 S 1 seeds, revealed that the gametes of the F 1 and BC 1 plants carrying a greater number of A-genome chromosomes were more viable. This resulted in a signiWcantly greater number of intermediate and a smaller number of high-erucic acid BC 1 S 1 seeds.

Exploitation of the late flowering species Brassica oleracea L. for the improvement of earliness in B. napus L.: an untraditional approach

“…In case of Brassica digenomic triploids derived from cross between amphidiploid and diploid species, such as hybrids of B. napus 9 B. rapa (Kubik et al 1999;Zaman 1988) or B. carinata 9 B. alboglabra (Rahman 2001), often stabilize into amphidiploid type. This is apparently due to high viability of the amphihaploid gametes as opposed to aneuploid gametes as inferred by Bennett et al (2008) based on inheritance of erucic acid content in self-pollinated generation of (B. napus 9 B. alboglabra) 9 B. alboglabra hybrids. Miller (2001) introgressed 3-6 days earliness of flowering from B. rapa into B. napus through application of DH technique on the interspecific hybrids of these two species.…”

“…For this, developing siliques at the age of 10-12 days after pollination (DAP) were harvested, and the fertilized ovules (developing and larger in size compared to unfertilized ovules) were excised and cultured in vitro. The details of the ovule culture technique and culture medium for generation of interspecific hybrid plants is described elsewhere (Bennett et al 2008). …”

“…However, the S 1 plants of the line DH10 produced on average 5.8 (range 0-18.7) and 16.1 (range 8.0-25.2) seeds per pollination on crossing with the B. alboglabra and B. napus parents, respectively. Interspecific crossing of B. napus and B. oleracea normally fails to produce almost any hybrid seed in vivo (Bennett et al 2008). Thus, a line such as DH10 could be an important source for use as a bridge for interspecific trait transfer between these two species due to its good crossability with both the species.…”

Broadening genetic diversity inBrassica napuscanola: Development of canola-quality springB. napusfromB. napus×B. oleraceavar.alboglabrainterspecific crosses

“…Plants were watered daily, and fertilized every week with 15Á30Á 15 NÁPÁK fertilizer. In vitro ovule culture technique applied for production of F 1 plants; the detail of this technique is described by Bennett et al (2008). F 1 plants were grown in 6-inch pots filled with SunGro † Sunshine Mix 4 in a growth chamber set at 20/158C day/night temperatures and a 16-h photoperiod with photosynthetic flux density of 450 mE m (2 s (1 at plant level.…”

“…Conversely, very little effort has been made to utilize the genetic diversity of B. oleracea for the improvement of B. napus through crosses between B. napus and B. oleracea. This is primarily due to the difficulty of producing B. napus )B. oleracea interspecific hybrids (Downey et al 1980;Quazi 1988;Bennett et al 2008). Moreover, all B. oleracea germplasm are not of canola-quality type; they contain high contents of erucic acid in seed oil and glucosinolate (GSL) in seed meal.…”