"George Coons (left) and Lee Ling, of the Food and Agriculture Organization in Rome, visit on the bank of the Po River near the Adriatic Sea (Porto Levante, Italy, 1951).
"Enrico Biancardi displays a very developed Beta maritima (Porto Levante, Italy, 2011).
"Robert Lewellen discovered the "Holly" resistance gene in 1985-1986.)
"Viacheslav and Helen Savitsky (Salt Lake City, 1959)
The story of crops is often under-appreciated. This is not a good thing, especially for the farmers who grow them. In fact, knowing what happened after the domestication and subsequent evolution of the modern varieties could help us better understand the needs of the species currently being cultivated on our farms.
Sugarbeets are one of the newer crops. They were created in Germany at the end of the 1700s and rapidly became the most important destination of the species Beta vulgaris. The sugarbeet's wild parent is the sea beet (Beta maritima), still living on the European seashores and whose leaves were harvested and eaten by prehistoric man. After domestication (about 8,500 B.C.), the species first was cultivated for the leaves, but the unconscious selection performed by the ancient farmers led to garden, or red, beets (around 100 B.C.) and the fodder beets. The latter appeared in Europe around 1500 A.D., and the sugarbeet was likely selected from it. Progress in sugar yield, reduction of costs and manpower requirements, processing quality, etc. has been impressive in these past 200 years since the creation of the sugarbeet. What is sown today is considerably different from the first sugarbeet varieties.
The history of a friendly and partly informal collaboration between American and Italian official research stations will be summarized here. Notwithstanding, it is still a rather unknown activity that resulted in findings that improved worldwide performance of sugarbeets. One could say that some traits of the modern varieties, including important disease resistances, originated and were distributed thanks to the mentioned cooperation.
The history begins exactly one century ago, when the Italian breeder Ottavio Munerati, working for the Royal Sugarbeet Research Station at Rovigo, Italy (a small town near the Po River Delta), initiated crosses between sugarbeets and Beta maritima.
According to other authors, Munerati hypothesized that several traits of the wild parent disappeared gradually in the crop variety due to the unconscious selection applied after domestication. It is well known that the cultivated species are much more delicate and require more protection and care than their wild parents. In other words, the enhancement of the qualities requested by the farmers was purchased with the loss of wild and potentially useful traits.
Munerati speculated that the recovery of such traits, including likely resistances against some severe diseases, could be a feasible and powerful means for increasing yield.
Around 20 years later, by means of intensive crosses between sugarbeets and seabeets collected in the Po Delta, Munerati obtained sugarbeets endowed with resistance to cercospora leaf spot (CLS). But the derived hybrids still displayed a number of negative characteristics from the wild parents. The leaf canopy was very vigorous but multicrowned, and the roots were observed to be fangy and irregular in shape. The best lines tended to flower later and displayed high sugar content but poor root yield. For these reasons, the hybrids again underwent several cycles of selection in order to eliminate the undesired characteristics.
George H. Coons was a plant pathologist for the Division of Sugar Plant Investigations, USDA Bureau of Plant Industry, from 1925 to 1955. He was involved in the diseases of sugarbeet and also in development of breeding lines, parental lines and varieties with resistance to cercospora leaf spot, virus yellows and curly top virus. He met with Munerati in Italy in 1925 and 1935. After the second visit at Rovigo, he wrote, "Munerati gave me seed of his best variety [resistant to CLS] RO 581."
At the time, it must be recalled; lines and varieties selected by the Rovigo Station were released only in a strictly official way and exclusively to Italian, German and Japanese seed companies. In the new American environment, the variety was repeatedly and intensively tested under severe CLS attack. According to Coons, the Italian accessions showed resistance to CLS and even under diseased conditions allowed substantial improvement of sugar production. It is well known that even after about 70 years, this is the most important genetic resistance available against CLS.
Similarly successful results occurred in the field of rhizomania resistance. Munerati didn't directly know the disease, the cause of which was first discovered in Italy in 1966, 17 years after his death.
However, in CLS-resistant materials, and therefore derived from his genotypes, the very first type of resistance to rhizomania, called "Type Alba," was found. The name was given because the seed company Alba bought the main part of Munerati's germplasm in 1949. The superior performance of multigerm variety "Alba P" was observed initially in trials grown in 1957, well before the discovery of the agents causing the disease. More recently, based upon observation of segregating populations, this kind of resistance was classified as quantitative by Enrico Biancardi at Rovigo.
The more resistant variety, "Rizor," was released in 1985 by SES-Italy after being discovered and developed by Marco De Biaggi. In field trials grown in 1980, De Biaggi included some CLS-resistant genotypes that would have originated from germplasm selected by Munerati. In a trial located near Ravenna, an unexpected and strong rhizomania infection occurred. The yield of five genotypes was much better than other entries.
From these lines, the healthiest beets were submitted to the normal selection and breeding procedures. In 1984, a collaborative study was set up with the Bologna University, where the agents that caused rhizomania were discovered. It was established that the fungus Polymyxa betae infects the beet rootlets carrying and inoculating the virus, BNYVV. The virus moves rapidly through the root bundles of susceptible genotypes, whereas the movement in the roots of "Rizor" appeared to be hindered. Early in the selection program, the "Rizor type" resistance was recognized as monogenic and dominant.
In the summer of 1983, Alvin Erichsen, a breeder working for Holly Hybrids, observed very low sugar yield in a trial near Tracy, Calif., with the exception of three experimental hybrids which produced five times more than the susceptible check USH11. An ELISA test on the roots confirmed the presence of BNYVV. The hybrids had different pollinators, but the same female parent, obviously carrying some unknown resistance. During 1985 and 1986, the mentioned hybrids were evaluated by Robert Lewellen at Salinas, Calif., under severe rhizomania conditions. Compared with resistant varieties of European and Japanese origin, the trials confirmed the high level of resistance derived from the Holly seed bearer line.
Just as in the first trial, the three hybrids segregated in a pattern typical for a single dominant gene, subsequently called Rz. The "Holly" resistance gene reduces the BNYVV replication rate in the root. It was observed that the resistant (RzRz) genotypes had significantly lower virus titer than susceptible (rzrz) genotypes. In other words, "Rizor" and "Holly" resistances both seemed to limit the spread and replication of the virus inside the root. Recently, due to the similitude of the resistance traits, it was speculated that Holly resistance may have originated from old Italian material as well.
Viacheslav Savitsky was a leading sugarbeet breeder and geneticist in the former Soviet Union. He and his wife, Helen, immigrated to the United States after World War II. Helen was an excellent microscopist and cytologist. Before WWII, Savitsky had frequent and close contacts with Munerati, who understood Russian very well and therefore was updated on the research occurring in the USSR on selecting lines for monogerm seed. Surely, around 1935, Savitsky was provided with Munerati's CLS-resistant lines.
Around the same time, Savitsky discovered a quantitative form of monogermity defined as "Russian," but whose transmission was difficult to control in commercial seed multiplication. A monogenic type of monogermity was isolated as well. But the breeding work was stopped by the war. In 1946, Munerati wrote, "I hastily asked Savitsky for more details and for a small quantity of the new type of seed [carrying the monogenic trait], so I would be able to test it here." Obviously, the request could not be answered.
Thanks to Coons, in 1947, Savitsky was employed in the United States by the Beet Sugar Development Foundation and subsequently by the USDA. His first task at the Salt Lake City Station was to find possible sources of monogerm seed for the domestic sugarbeet growers and industry. At the time, the development of monogerm seed was becoming essential due to the costs of manually singling the beet crop. In this research, Savitsky collaborated with several American breeders, including Eubanks Carsner, John McFarlane, Forrest Owen, George Coons, Ray Pendleton and others. The group was charged with finding monogerm beets in different parts of the U.S.
Savitsky knew that the variety "Michigan Hybrid 18" was derived from the Polish CLS-resistant variety "Buszczynsky CLR," which had been obtained from Italian genotypes. He likely recalled in conversations with Munerati that in such materials tested in the USSR, a few monogerm plants were found. Cycles of inbreeding had been used in Italy to help in the identification of CLS resistance and this method possibly allowed the rare recessive monogerm trait to be expressed.
In fact, in a four-acre seed production field north of Salem, Ore., sown with Michigan Hybrid 18, Savitsky found five plants bearing monogerm seeds. In 1953, the selected offspring of the beet SLC 101 was made available to the American and European breeders, and after a few years, the monogerm varieties became all that was sown in developed countries.
Proof of Munerati's hidden and post mortem involvement in this discovery might be given by the fact that Coons brought an SLC 101 seed sample to Rovigo in July 1951, two years before its official release. The occasion was the grand opening of the new research facilities at the Rovigo Station, completely built with U.S. funds. This could be more evidence for the collective but unpublished knowledge and cooperation between scientists in Italy and the U.S. at this time.
Starting in the 1980s, the old, fruitful and traditional collaboration was continued between Lewellen and Biancardi - working at the stations of Salinas and Rovigo respectively - and increased time after time. The partnership has been expanded to the stations of USDA-ARS at Fort Collins, Colo.; East Lansing, Mich.; and Fargo, N.D. [with Leonard Panella, Mitch McGrath and Larry Campbell respectively], with important results and publications, as always, without specific financial support. An example is the book on Beta maritima recently published by Biancardi, Panella and Lewellen (reviewed by Sugar Producer, April 2012).
Piergiorgio Stevanato, currently working at the Padua University, is the new scientist in this continuing collaboration that has resulted in new research papers being published on germplasm resources, enhancement, genetics and molecular characterization. And so, the story goes on.