by Wagdy Sawahel, SciDev.Net

Researchers have found a way of boosting the yield of a major crop by stopping its seedpods from bursting open.

Indian mustard (Brassica juncea) is the most important oilseed crop in India after groundnut. It is grown largely to produce cooking oil from the seeds. However, because the seedpods open naturally to disperse their seeds at different times, part of each harvest is lost.

This 'pod shatter' also makes it difficult for farmers to rotate crops because prematurely released seeds can germinate and become weeds.

Researchers, led by Lars Østergaard from the University of California at San Diego, United States, created genetically modified (GM) Indian mustard whose seedpods will not open naturally. They did this by inserting a gene from a related plant called Arabidopsis.

Their research was published online by Plant Biotechnology Journal on 16 August

Østergaard says that controlling seedpod opening could have the added benefit of reducing the chance of the inserted genes moving to non-GM crops or wild species. He adds that the same approach could be used in other crops that disperse their seeds in a similar way, such as soybean and peas.

Indian mustard can tolerate heat and drought. Because of this, Australian crop breeders are crossing it with its close relative Brassica napus (canola or oilseed rape) — which produces a better quality oil — to create new varieties.

Østergaard says that combining the new drought resistant varieties with his teams' plants that do not shatter their seeds could yield crops that are well suited for the warmer climates of most developing countries.  

Abstract of paper in Plant Biotechnology Journal

Pod shatter-resistant Brassica fruit produced by ectopic expression of the FRUITFULL gene
Lars Østergaard, Sherry A. Kempin, Dawn Bies, Harry J. Klee and Martin F. Yanofsky

Arabidopsis has proven to be extremely useful as a reference organism for studies in plant biology, and huge efforts have been employed to unravel various mechanisms of Arabidopsis growth. A major challenge now is to demonstrate that this wealth of knowledge can be used for global agricultural and environmental improvement. Brassica species are closely related to Arabidopsis and represent ideal candidates for model-to-crop approaches as they include important crop plants, such as canola. Brassica plants normally disperse their seeds by a pod-shattering mechanism. Although this mechanism is an advantage in nature, unsynchronized pod shatter constitutes one of the biggest problems for canola farmers. Here, we show that ectopic expression of the Arabidopsis FRUITFULL gene in Brassica juncea is sufficient to produce pod shatter-resistant Brassica fruit and that the genetic pathway leading to valve margin specification is conserved between Arabidopsis and Brassica. These studies demonstrate a genetic strategy for the control of seed dispersal that should be generally applicable to diverse Brassica crop species to reduce seed loss.

Reference:
Plant Biotechnology Journal doi: 10.1111/j.1467-7652.2005.00156.x (2005)