Zhongyang Zhang | ALES Graduate Seminar

A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Zhongyang Zhang. This seminar is open to the general public to attend. Room capacity is limited to 20 observers; masks are required, and anyone with Covid symptoms should not attend.

Thesis Topic: Introgression of the Clubroot Resistance from Brassica oleracea into B. napus Canola through Interspecific Cross

MSc with Dr. Habib Rahman

Seminar Abstract:

Clubroot disease caused by Plasmodiophora Brassicae Woronin is a serious threat to canola production in Canada. Most of the available clubroot-resistant canola cultivars carry major resistance genes of the Brassica A genome. However, the ineffectiveness of this type of resistance has been reported in Canada. On the other hand, clubroot resistance of the C genome of B. oleracea is under quantitative genetic control; this type of resistance is expected to provide a durable resistance in canola. The objective of this thesis research was to investigate the prospects of introgression of the C-genome resistance from B. oleracea into B. napus canola through interspecific hybridization between these two species. For this, B. napus × B. oleracea var. acephala (clubroot resistant) interspecific hybrids were produced through the application of the in-vitro ovule culture technique. Following this approach, 12 hybrids from a total of 175 pollinations were obtained. The F1 plants were self-pollinated for F2 seeds and backcrossed to the B. napus parent for BC1 seeds, and the F2 and BC1 populations were self-pollinated to produce F3 and BC1F2 populations. The F1 plants exhibited high sterility and produced only 0.168 seeds per self-pollination and 0.064 seeds per cross-pollination with the B. napus parent. The F2 and BC1 populations were evaluated for agronomic and seed quality traits. These two populations required around 70 and 40 days more time on average to flower as compared to the B. napus parent, and plants flowering earlier than the B. napus parent could be found in these populations. The average erucic acid in F3 and BC1F2 seeds, harvested from the F2 and BC1 plants, was 13.4 and 6.8%, and glucosinolate content was 37.4 and 30.3 μmol/g seed, respectively. Nevertheless, zero erucic acid and low glucosinolate plants could be obtained from both populations. Plants exhibiting resistance to pathotype 3H could be found in F3 and F4, but not in the BC1F2 population. Several F3 plants had nuclear DNA content similar to the B. napus parent. In addition to the above-mentioned populations, different advanced generation populations of B. napus × B. oleracea vars. capitata and gemmifera (clubroot resistant) interspecific crosses were also evaluated for resistance to pathotype 3H and 3A. Selection for resistant plants and self- pollination of the selected plants was carried out up to F9 generation, from where a clubroot resistant line was achieved from B. napus × B. oleracea var. capitata cv. Bindsachsener interspecific cross. B. oleracea-specific simple-sequence repeat (SSR) marker alleles could be detected in the clubroot-resistant F8 plants of this cross. However, the association between the marker alleles and clubroot resistance could not be established. The results from this thesis research demonstrated the prospects of developing clubroot resistant canola lines from the B. napus × B. oleracea interspecific crosses.