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Heat Genes Influence Flowering of Foreign Canola

Research published in PLOS ONE has determined why Australian canola flower earlier than its Canadian and European counterparts.

Since Australian canola flowers much earlier than these foreign varieties, plant breeders cannot simply transfer varieties from Canada or Europe as they flower much too late for the Australian environment.

A/Prof Matthew Nelson of The University of Western Australia’s School of Plant Biology has found that heat-responsive genes are responsible for the disparity in flowering time between Australian spring-type and European summer-type canola. This is the first time such genes have been reported to influence flowering time in canola.

“We took a European summer-type canola, crossed it with Monty, a typical early-flowering Australian variety, and analysed the progeny for variation in flowering time,” Nelson said. “There was a huge variation from about 30 days to 160 days in our typical Australian environment. This was totally unexpected, and we showed there are several forms of these heat-responsive genes controlling flowering time.”

The research indicated that the European plants required much more accumulated heat to flower than the Australian plants. “Until now, most researchers assumed that long summer days in Europe and Canada triggered flowering, not heat,” Nelson said. “Now we know that long days are only a minor part of the story.”

“Understanding this complex process is important as breeders alter the adaptation of crops to a new and changing environment,” said Prof Wallace Cowling of UWA. “International canola breeders will use this information to re-establish the correct flowering time in canola when they cross between Australian types and summer annual types in the Northern Hemisphere. With increasing global temperatures, or in low rainfall environments, it will be possible to ‘mix and match’ forms of these heat genes to achieve the target flowering date.”

Since day length affects both European and Australian varieties equally, the research group can now focus on heat genes to predict the outcomes from crossing European or Canadian canola with Australian canola and explain what caused these genes to respond to accumulated heat.