“You Say Tomato, I Say Genomics”: Genome Sequences for Two Wild Tomato Ancestors

By | Agriculture, Fruits and Vegetables, News, Plant Science

Tomatoes are one of the most popular types of fresh produce consumed worldwide, as well as being an important ingredient in many manufactured foods. As with other cultivated crops, some potentially useful genes that were present in its South American ancestors were lost during domestication and breeding of the modern tomato, Solanum lycopersicum var. lycopersicum. Because of its importance as a crop, the tomato genome sequence was completed and published as long ago as 2012, with later additions and improvements. Now researchers have produced high-quality genome sequences of two wild ancestors of tomato from Peru, Solanum pimpinellifolium and Solanum lycopersicum var. cerasiforme.

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Building a corn cob—cell by cell, gene by gene

By | Agriculture, News, Plant Science

Corn hasn’t always been the sweet, juicy delight that we know today. And, without adapting to a rapidly changing climate, it is at risk of losing its place as a food staple. Putting together a plant is a genetic puzzle, with hundreds of genes working together as it grows. Researchers have worked to study genes involved in corn development by analyzing thousands of individual cells that make up the developing corn ear. They created the first anatomical map that shows where and when important genes turn on and off during key steps in development. This map is an important tool for growing better crops.

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Study Finds Hidden Conflict in the Mutually Beneficial Relationship Between Legumes and Rhizobia

By | Agriculture, News, Plant Science

The mutually beneficial relationship between legumes and rhizobia, the nitrogen-fixing soil bacteria that make their home in legume root nodules and create nutrient-rich fertilizer for them, is one of the most well-known and agronomically important examples of symbiosis. New research from Dr. Kenjiro Quides, a Postdoctoral Teaching and Research Fellow in the Grand Challenges Initiative at Chapman University, tested the boundaries of this relationship — and found that it’s not always as perfectly harmonious as previously thought. 

The results are reported in a new paper in the journal Evolution

Legumes provide carbohydrates for rhizobial bacteria that live in root nodules, while the rhizobia fix atmospheric nitrogen into a form that’s usable for the legume (nitrogen is often a limiting nutrient for plants). In theory, if legumes have greater root nodule growth, they should be able to host more rhizobia, which should produce more nitrogen and enable larger plant growth in general.

The research, carried out by Quides and colleagues at UC Riverside during his doctorate, tested the relationship between root nodule growth and rhizobia using a smaller relative of Soybeans, named Lotus japonicus. By using multiple genetic variants that formed a low, medium, and high number of nodules, the study showed that legumes grew to maximum size when a low and medium number of nodules formed, but legumes that formed a high number of nodules had drastically reduced growth. 

The investigation then turned to the rhizobia. The size of the rhizobial population, a standard measure of bacterial growth, was found to continue to increase as the number of nodules formed increased. This suggests a hidden conflict in the symbiotic relationship. It seems that the legume and rhizobia interests are only aligned until the host optimum is reached, a point at which their interests diverge. This provides support for the conclusion that in the symbiotic relationship, rhizobia have an evolutionary advantage.

The results demonstrate that to avoid conflict in symbiotic relationships, hosts must tightly regulate their investment into symbiotic organs (like legumes’ root nodules) to maximize their own benefit-to-cost ratio of associating with their symbiotic partner. 

“Legumes seem to play a balancing act to maximize their growth, but rhizobia continue to grow and that is a really exciting result,” Dr. Quides said.

He noted that this study opens the door to more research. “Although we found diminishing returns for the host from nodulation, the fact that rhizobia population size continued to increase is promising. We found the costs outweigh the benefits at high nodule numbers. However, if we can increase the number of nodules and therefore the rhizobia population size while minimizing the cost to the plant, we have the potential to increase the productivity of legume crops in the future.”

Read the paper: Evolution

Article source: Chapman University

Image: A cluster of nodules on the roots of the plant Lotus japonicus. Bacterial rhizobia are housed within root nodules and supplied with carbohydrates from the host plant. The carbohydrates are used by rhizobia in exchange for the fixation of nitrogen then used by the plant. Credit: K. Quides


New heat method kills pathogens with minimal damage to plants

By | Agriculture, Fruits and Vegetables, News, Plant Health

In the strawberry nursery industry, a nursery’s reputation relies on their ability to produce disease- and insect-free plants. The best way to produce clean plants is to start with clean planting stock. Many nurseries struggle with angular leaf spot of strawberry, a serious disease that can result in severe losses either by directly damaging the plant or indirectly through a violation of quarantine standards within the industry.

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The regulatory network of sugar and organic acid in watermelon fruit is revealed

By | Agriculture, Fruits and Vegetables, News, Plant Science

The sensory quality of watermelon fruit is determined by the content of sugar and organic acid, which determines the taste of watermelon during the development and maturation of watermelon fruit. The changes of sugar and organic acid during the watermelon fruit development were analyzed and the key gene networks controlling the metabolism of sugar and organic acid during the fruit development were identified.

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