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...And find out how to make your lentils survive the winter. That has been part of high-tech PhD thesis work that has been going on at ICARDA.

map them. Just as you use aerial photography to find out where a natural feature such as a watercourse goes, you can photograph the structure of a chain of genes to find out where it will lead you."
      Scientists will start with the plant itself. Parent plants with known phenotypic characteristics--that is, color, size, time to flowering and maturity, yield, tolerance to pests and climatic conditions--will be crossed to produce the hybrid, which is the product to be studied. In this case, an ICARDA lentil variety (known as Talia in Lebanon)  of known good performance was crossed with a wild lentil from ICARDA's genebank to produce a population of progenies with a combination of genes that would repay study.
      The next target is the genome. This is the structure inside a cell made up of chromosomes. The chromosomes are rods made up of the genes in order, and it is this order that the scientist wants to see. To get at it, the researcher physically and chemically breaks down the structure of the cell, dissolving the proteins, the cell wall and nucleus membrane. The chromosomes are then left free in a solution, and can be studied.
       "There is actually nothing magic about this," says Imad Eujayl. "It is, of course, physical matter, and if you can look at something, then you may be able to understand it".
       "Genes are made out of DNA--the stuff of life itself". DNA is a molecule in an acid form. It is made of four elements called nucleotides, composed of phosphate, the sugar deoxyribose and a nitrogene base. These make up two strands which twist around each other. This double twist is what is called the double helix and it is this that caused such excitement when it was discovered in the 1950s.
      "What you need to understand is that the helices are made up in a certain sequence and combination of nucleotides. It is these different combinations of chemicals making up the DNA that are in fact the traits/characteristics. Several hundred or

farmers who are dependent or partially dependent on this important food crop. He will be defending the resulting PhD thesis at the University of Helsinki in Finland early in 1998.
"I am from the Sudan, where we use lentil a lot. It's an important source of protein," says Mr Eujayl. "It's our breakfast--we call it addis--and our national program has made great strides in lentil production over the last few years. But all producers can use better disease resistance." (ICARDA worked with Sudan on the country's plan for lentil--see Caravan No. 2.) ICARDA is currently developing cold-tolerant lentil varieties to increase productivity in the highlands of West Asia and North Africa--often the least-developed parts of the region. So cold-tolerant varieties could have a significant impact on poverty.
Mr Eujayl has been working with ICARDA for some years. After he graduated in agriculture from the University of the Gezira, Wad Medani, in Sudan in 1985, he became a teaching assistant at the University of Science and Technology in Khartoum. In 1991 he came to ICARDA to do an MSc in tissue culture (he specialized in horticulture at Wad Medani). In 1993 he joined the Center's staff and also began his PhD work.
  "It is worth explaining how gene mapping is done, because we can dispel a few myths about biotechnology," says Mr Eujayl. "The cloning of a sheep in Scotland recently has led some people to see biotechnology as something mysterious and rather sinister. It's true that it has implications for the future, and must be used responsibly. But this applies to any form of technology.
"What we do at ICARDA is actually quite simple, at least in theory. Characteristics of any species are passed from one generation to another in the genes. We physically look at the the genes and see what is there. Then we

ow do you breed crop varieties for tolerance to climatic extremes and pests and diseases? You must cross various lines which have such traits and select the progenies until you have what you want in one plant. But this takes time. Biotechnology can speed the process.
Using it, PhD researcher Imad Eujayl has just succeeded in tracking the genes for frost susceptibility and vascular wilt in lentil. He used a technique called gene mapping, which is being used more and more at ICARDA. This will have real advantages for