**4. Vitamins**

have a hydroxyl group at C-3, a trans-A/B ring system and an intact nonhydroxylated side chain but lack methyl groups at C-4 [52]. Plant sterols are different than animal sterols with plants being unique in methyl, ethyl or related alkyl groups at the C-24 position of the sterol side chain [52]. There are also differences between plant sterols and plant-parasitic nematode sterols. These findings suggest that nematodes ingest plant sterols and remove the C-24 side chain. In addition, the nematode saturates the double bonds in the four-membered ring system to produce stannols [52]. Steroid hormones are important in development processes and in transition to different life stages [53]. Most likely genetic and biochemical methods will be needed to determine the function of hormones found in nematodes [54]. Novel genes involved in the production of 17β-hydroxysteroid dehydrogenase in the soybean cyst nematode have

Sterols were first reported in soy oil by Kraybill et al. [56]. Formononetin is an o-methylisoflavone mainly produced in legumes, including soybean plants [57]. It helps stimulate the production of steroids in mammals, and possibly also in nematodes. Research in this area by

There are no clearly defined requirements for proteins, amino acids, or peptides for SCN. However, it is unlikely that nematodes synthesize all the amino acids. For humans, there are 9 essential amino acids [phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, and histidine]. Some others are required under special circumstances [arginine, cysteine, glutamine, proline, serine, tyrosine, and asparagiene]. Cysteine, tyrosine, and arginine are required during rapid growth, such as in infancy. And, arginine, cysteine, glycine, glutamine, histidine, proline, serine and tyrosine are required by some individuals because these amino acids are not adequately synthesized by these individuals. These are essential components for the synthesis of many essential enzymes and structural proteins ; it is antici‐

Protein consumed by parasitic nematodes can severely damage the host. Juveniles have high protein requirements and consuming the host protein can severely weaken the plant [46].

There have been efforts to identify the essential amino acids of nematodes [59-61], but so far common requirements have not been identified. However, protein synthesis in cotton roots is modified when the root-knot nematode [RKN] infects susceptible plants. These plant-parasitic nematodes influence the distribution of amino acids in cotton root galls [61]. Also, there is one genetic modification of the cotton plant which makes them less susceptible to infection by the

For the snail parasitic nematode, *Rhabditis maupasi*, five essential amino acids have been identified. These include lysine, methionine, phenylalanine, tryptophane, and valine [62]. In the entomophilic locust parasite, *M. migrescens*, essential nutrients include protein nitrogen

[63]. Essential amino acids have also been identified for the nematode *C. briggsae* [64].

RKN. This modification is responsible for the synthesis of a 14 kDa protein [60].

been reported [55].

8 Soybean - Pest Resistance

the USDA was reviewed by Chitwood [58].

pated there are similar needs in the nematode diet.

**3. Amino acids and proteins**

There are 13 essential vitamins required by humans. These include Vitamin A [Retinol] Vitamin B1 [Thiamine] Vitamin C [Ascorbic acid] Vitamin D [Calciferol] Vitamin B2 [Ribofla‐ vin] Vitamin E [Tocopherol] Vitamin B12 [Cobalamins] Vitamin K1 [Phylloquinone] Vitamin B5 [Pantothenic acid] Vitamin B7 [Biotin] Vitamin B6 [Pyridoxine] Vitamin B3 [Niacin] Vitamin B9 [Folic acid]. Of these, vitamin E is known to be a nutritional requirement for the gastroin‐ testinal parasite, *Heligmosomoides bakeri* [65], and several of the B vitamins are known to be essential nutrients of *C. elegans* [66-68].

For SCN, DNA sequences responsible for the biosynthesis of enzymes that can produce some of the B vitamins *de novo* have been discovered [69]. Therefore, SCN may not need the same B vitamins as *H. bakeri*, for example. And, it is likely that there are other differences in vitamin and supplement requirements across all nematodes.
