This is the fourth in a series of posts reviewing the 17 articles found in the October 2014 Special Issue of American Journal of Botany, Speaking of Food: Connecting Basic and Applied Science.

Genetic Diversity in Carthamus tinctorius (Asteraceae; Safflower), An Underutilized Oilseed Crop by Stephanie A. Pearl and John M. Burke

Safflower (Carthamus tinctorius) was first domesticated in the Fertile Crescent about 4,500 years ago. It was originally desired for its flowers which were used in dye making. Commercial production of safflower began in North America in the 1950’s, where it is now mainly grown for its seeds which are used to produce oil for human consumption and are a main ingredient in bird seed mixes. Despite this, it is categorized as an “underutilized crop,” one “whose genetic potential has not been fully realized.” With increased interest in food security and feeding a growing population, researchers are turning to new and underutilized crops in order to increase the “availability of a diverse assemblage of crop species.”

A major step in improving a crop plant is understanding the genetic diversity that is available within its gene pool. With this aim in mind, researchers observed a “broad cross section of the safflower gene pool” by examining the DNA of a “worldwide sampling of diversity from the USDA germplasm collection [134 accessions consisting of 96 from the Old World and 38 from the New World]”, 48 lines from two major commercial safflower breeding programs in North America, and 8 wild collected safflower individuals.

Safflower, Carthamus tinctorius (photo credit: www.eol.org)

Researchers found that the cultivated safflower varieties had a significant reduction in genetic diversity compared to the wild safflower plants. They also noted that the 96 Old World accessions could be grouped into “four clusters that corresponded to four different geographic regions that presumably represent somewhat distinct breeding pools.” They found that the wild safflowers “shared the greatest similarity with the Iran-Afghanistan-Turkey cluster” from the Old World group of accessions, a finding that “is consistent with safflower’s presumed Near Eastern center of origin.”

The researchers determined that there may be “agronomically favorable alleles present in wild safflowers,” and that “expanded efforts to access wild genetic diversity would facilitate the continued improvement of safflower.” Safflower is an important but underused oilseed crop that is adapted to dry climates; studies like this one that can lead to further crop improvements may help bring it out of niche production and into more widespread use.

The Wild Side of a Major Crop: Soybean’s Perennial Cousins from Down Under by Sue Sherman-Broyles, Aureliano Bombarely, Adrian F. Powell, Jane L. Doyle, Ashley N. Egan, Jeremy E. Coate, and Jeff J. Doyle

Soybean production is a major money maker in the United States ($43 billion total revenue in 2012); corn is the only crop that tops it. Soybean oil has myriad uses from food to feedstock and from pharmaceuticals to biofuel. As much as 57% of the world’s seed oil comes from soybeans produced in the United States. Hence, soybean (Glycine max and its wild progenitor, G. soja) is a well researched crop. Most research has been focused on the two annual species in the subgenus Soja; “less well known are the perennial wild relatives of soybean native to Australia, a diverse and interesting group that has been the focus of research in several laboratories.”

Given the agricultural importance of soybean and the increasing demands that will be placed on this crop as population rises, it is imperative that improvements continue to be made. Exploring soybean’s “extended gene pool,” including both its annual “brother” and its perennial “cousins,” will aid in making these improvements.

Soybean’s wild annual relative, Glycine soja (photo credit: www.eol.org)

Perennial soybeans in the subgenus Glycine include around 30 species. They are adapted to a wide variety of habitats “including desert, sandy beaches, rocky outcrops, and monsoonal, temperate, and subtropical forests.” They are of particular interest to researchers because several of them are allopolyploids, meaning that they have more than the usual two sets of chromosomes and that the additional sets of chromosomes were derived from different species. The authors state that “the distributional differences between diploids and independently formed polyploids [in the subgenus Glycine] suggests underlying ecological, physiological, and molecular differences related to genome doubling and has led to the development of the group as a model for studying allopolyploidy.” The group is also worth studying because they demonstrate resistance to various soybean pathogens and are adapted to a variety of environmental conditions.

By continuing to work with soybean’s perennial cousins to gain a better understanding of “polyploidy and legume evolution,” the authors hope to apply their research to achieve increases in soybean yields. Past research suggests that the study of polyploidy in the perennial soybeans could lead to crop improvements in areas such as photosynthesis, nitrogen fixation, flowering time, and disease resistance.

Glycine tomentella – one of soybean’s perennial cousins (photo credit: www.eol.org)