22 SCIENCE

Pathways for Introgression of Pest Resistance into hypogaea L.' Charles E. Simpson!

ABSTRACT The search for variability for use in improvement of the Fourpathways for gene introgression into Arachis hypogaea L. cultivatedpeanut,Arachishypogaea L. (called groundnutin were studied. Two "hexaploid routes" involved direct crosses of diploid Arachis species and diploid species hybrids with A.hypogaea much of theworld), has focused on plantintroductions since (Pathways 1 and 2, respectively) and were followed by chromosome the early stages ofpeanut breeding in the USA. In the mid­ doubling with colchicine. A third pathway, a tetraploid route, 1940's the possibility offinding needed variability in other involved chromosome doubling of a diploid hybrid before crossing species came to the attention of Gregory (5, 6, 7) and with A. hypogaea. These first three routes involved only the A Krapovickas (12). Considerable attention has been given to genome species, and all were unsuccessful because of lack of fertility. The fourth pathway, also a tetraploid route, utilized the B searching for, collecting, introducing, preserving, and genome A. batizocoi Krap, et Greg. as a bridge species and brought evaluatinggermplasmin the form ofwild Arachis species (8, about a successful (fertile) introgression. Genes from A. cardenasii 25), and effort has been directed toward utilization of the Krap. et Greg. nom. nud. andA. chacoensis Krap et Greg. nom. nud. wild species in improvement of the cultigen (1, 2, 14, 28, 30, were combined into a hybrid and incorporated into A. hypogaea by using the B genome bridge species. Introgression of additional 31,40,42). characters from these and other species through this pathway should be possible. In Arachis, the most devastating diseases world wide include the leafspots, early ( arachidicola Hori) and late [Cercosporidium personatum (Berk. and Curt.) Key Words: Peanut, groundnut, Arachis hypogaea L., Deighton] (21, 41). Thousands of A. hypogaea lines have interspecific hybrids, introgression, leafspot, nematode, resistance, been evaluated for resistance to these two organisms, and wild species. some lines with resistance have been identified (13, 21, 35, 41). Attempts to utilize this resistance have been made by numerous breeders [13, and see reviews by Gregory (7), Norden (18), Norden et al. (19) Stalker and Moss (40), and "Texas Agricultural Experiment Station, Texas A&M UniversityTA No. 25605. Wynne and Halward (42)], with limited success. Recently 2Professor, Texas Agricultural Experiment Station, Texas A&M the first cultivarwith resistance to late leafspot was released University, Stephenville, TX 76401. by Gorbet and co-workers (3).

Peanut Science (1991) 18:22-26 INTROGRESSION IN ARACHIS 23

Abdou et al. (1) determined that A. chacoensis Krap et as described by Banks (2). Pollen was stained in a 1:1 mixture of Greg. nom. nud. (GKP-I0602, PI-276235) had a high level acetocarmine/glycerin. Pollen counts were made by placing the pollen from one flower under a 22 mm" coverslip with acetocarmine/glycerin, of resistance to early leafspot, and A. cardenasii Krap et taking the mean of five 100-grain counts made from random fields Greg. nom. nud. (GKP-I0017, PI-262141) was immune to (maximum of ten grains per field), and making three flower counts per late leafspot. The results ofShariefet al. (22) indicated that on separate days. These pollen counts were made on all which the genes for the resistance to these two diseases were not at flowered, with the exceptions noted in Table 1. Plants were grown in deep soil benches, claypots, or lined fruit baskets. thesame loci; thus, providinga possibilitythattheresistances In the short days of winter, daylength was extended to 12 h by using could be combined into one genotype, as suggested by incandescentplantgrowth bulbs. Plants were inoculatedwith a commerical Smartt et al. (34). Rhizobium inoculum. The soil was a mix of fine sandy loam top soil and Recently, Nelson et al. (15) identified high levels of builders sand or washed river sand mixed in a 1:1 ratio. Final sand content resistance to root-knot nematode, Meloidogyne arenaria of the soil mix was approximately 92%. Leafspot resistance was determinedin laboratoryexperiments by using (Neal) Chitwood in twenty-one Arachis species. Within this a modification of the detached leaf technique described by Melouk and group, the best resistance to M. arenaria was identified in A. Banks (13). Field screeningwas accomplished by using the ICRISATscale cardenasii (GKP-I0017) andA. batizocoi Krap. et. Greg. (K­ (41) or the Florida scale (11) for late leafspot. Nematode studies were 9484) (PI-298639). Thesetwo species representtwo different described by Nelson et al. (15). resistance mechanisms (15). Parent numbers used in these studies correspond to parent numbers cited by Gregory and Gregory (4) for parents 19,34, and 37. However, parents Smarttet al. (33) identified two genomes (Aand B) in the 82 and 83 were not the same germplasm as those used by Gregory and section Arachis, both of which occur in the tetraploid A. Gregory (4). The four pathways studied are outlined in Tables 1 and 2. hypogaea. Chromosome analyses by Stalker and Dalmacio (39) and by Singh and Moss (26) strongly support the two Results and Discussion genome theory. Most diploid wild species which have been Pathway 1 identified as section Arachis have the A genome, including My first attempts to transfer leafspot resistance were A. cardenasii andA. chacoensis. Progenyfrom crosseswithin made by crossing parents 34 and 37 directly to parent 82. theAgenome have varying levels offertility (4,26,27,32,36, Triploids from A. hypogaea X 34 and 37 were produced and 38). Arachis batizocoi is the only diploid B genome species treated with colchicine to obtain hexaploids, Table 1 shows which has been identified to date. the pollen counts andploidy ofthesehybrids and amphiploids. When wild diploid Arachis species are crossed directly Meiotic behaviorofthe triploids was similar to that reported with the cultigen,A. hypogaea, triploids are producedwhich for other triploids (14, 24, 29, 30, 32, 37). The hexaploids are essentially sterile. However, several studies have shown were backcrossed to the A. hypogaea parent to produce that triploids between many A genome diploids and A. pentaploid progeny (Table 1); however, a high level of hypogaea produce varying degrees ofpeg, pod, and seed set sterility was encountered in the subsequent backcross and (22,24,27,32,34,38). the pentaploids produced no seed (Table 1). This pathway Wild Arachis genes have been introgressed into A. has been used with some success by others (40,42). hypogaea. See the review by Stalker and Moss (40) for a completedescription ofthese reports. Theobjectiveofthese Table 1. Fourpathways in attempts to introgress wildArachis genes studieswas to develop a consistentpathwayfor introgressing into A. hypogaea. Path· Ploidy of Year Number" Pollen Counts" see!~el wildArachis genes for pestresistance intoA. hypogaea. This ways CROSS hybrid observed average range yes/no paper reports on four attempted procedures. %% The efforts began in 1970 (Table 1), and have continued 82X34' sx 1970 7(P) 5 2to 7 V 82X37 sx 1970 16(P) 6 .OSto 12 V to the present (Table 2). (82X34)C2 6x 1971 10(P) 23 14 to 37 V (82X37)c ex 1971 10(P) 7 4to 12 V 82X(82X34) c 5x 1972 sterile" N Materials and Methods 82X(82X37) c sx 1972 sterile" N 34X37 2x 1973 14(F) 59 53 to 62 V The cultigens used in this research came from two of the four market 82X(34X37) 3x 1974 56(P) 18 1 to 93 V classes. Spantex and .Tamnut 74 (parent 82) represented the spanish [82X(34X37)] c ex 1974 5(F) 10 6to 12 V O· market type, and UF-439-16-1O-3-2 (parent 83), one of three sister lines 82X[82X(34X37)] C 5x 1975 N comprising 'Flo runner' (9, 16), represented the runner market type. 3 (34X37)° 4x 1975 61(P) 68 01099 V 3 82X(34X37) 0 4x 1975 6(P) 31 17 to 42 V Spantex was used as parent 82 until 1973, then Tamnut 74 was substituted 3 82X[82X{34X37) c] 4x 1976 27'(P) N for the old "landrace" variety. Tamnut 74 was derived from a crossing 4 19X(34X37) 2x 1976 29(P) 0.6 OtoO.8 N scheme which involved A. rrwnticola Krap. et Rig., but the cuItivar is 4 [19X(34X37)] 0 4x 1976 5(P) 78 70 to 92 V 8 classified as subspecies fastigiata var. vulgare (23). Florunner has some 4 82X[19X(34X37)] 0 4x 1977 group 1(P) 7 Oto 24 V spanish germplasm in its pedigree but is classified as subspecies hypogaea 4 82X[19X(34X37)] e 4x 1978 group 2(P) 29 27 to 32 V 4 83X[19X(34X37)) C 4x 1977 group 1(P) 15 2t031 V var. hypogaea (16). 4 83X[19X(34X37)]c 4x 1977 group 2(P) 19 8t037 V The wild species used in this program were collected in South America 4 83X[19X(34X37)) C 4x 1978 group 3(P) 32 29 to 35 V during the 1950's. Arachis batizocoi (K-9484)(parent 19) was collected in 4 82X[82X(19X(34X37» oJ' 4x 1979 17(P) 30 14 to 68 y 4 83X[83X(19X(34X37» oJ' 4x 1979 37(P) 40 9t079 Y Southeast Bolivia and is thought by many to be one of the original parents of A. hypogaea (33). Arachis cardenasii (GKP-10017) (parent 34) was found near Robore in Eastern Boliviaand has been proposed as one of the • Number of flowers (F) on one plant. or number of plants (P) observed. "Percentage of stained (viable) pollen, rounded to whole numbers. parents of A. hypogaea (33). Arachis chacoensis (GKP-10602) (parent 37) 1 Parental numbers used to identify parents in program. was collected in north central Paraguay. All three species are diploid; A. 19=~~ (K-9484). 34=.A. ~ (GKP-10017). batizocoi is annual and the other two are perennials. 37=.A. ~ (GKP-10602). Standard cross pollination techniques were used in hybridization work 82=h. ~ var. .l!l.!!gm (Spantex through 1973). 82=h. ~ var. .l!l.!!gm (Tamnut 74 after 1973). as described by Norden (17). Cytological material was fixed in 1:1 alcohol/ 83=1>.~ var. ~ (UF-439-16-1C-3-2. component line of Florunner). acetic acid, modified (95% alcohol instead of 100%) Carney's or modified 2 Treated with colchicine to double the chromosome number. 3 The only flowers produced were used for crossing attempts. (added5 mL chloroform/Inn mL) FAA solutions (10). Chromosomes were 4 All embryos aborted. stained in acetocarmine or aceto-orcein. Chromosome numbers were 5 All plants were weak, none produced viable seeds. doubled by treating cuttings with 0.02% colchicine or by treating seedlings 6 A group represents from 4 to 7 plants from one F,. 7 Backcross one. 24 PEANUT SCIENCE

Pathway 2 In an attempt to accelerate the introgression of disease Attempts to hybridize A. cardenasii (parent 34) and A. resistance into A. hypogaea, the subsequent testing and chacoensis (parent37) to combinethe two leafspot resistances backcrossing after the BCl generation was all done using met with complete failure when pollinations were made greenhouse and laboratory techniques, whereby BCnFl's inside the greenhouse. Success was achieved by growing the were tested for leafspot resistance and plants identified as female parent (parent 34) outdoors, where one seed was resistant were again backcrossed to A. hypogaea (Table 2). obtainedaftermaking 3500 pollinations. Theresultingdiploid The stainable pollen count datapresented in Table 2 for the hybrid plantwas crossed (as a male parent) with Tamnut 74 sixbackcross generations show thatthe stainablilityofpollen (parent 82), producing triploids, Colchicine treatment of 4' increasedfrom BCl to BC The data for BCsand BC6 do not triploid seeds resulted in one partially fertile hexaploid appear to reflect increases; however, this may not be the

(Table 1). The first backcross to parent 82 produced a case. Beginning in 1985 (last halfofBC4 cycle, i.e., parent82 pentaploid thatclosely resembled theA. hypogaeaparentin backcross) andcontinuingto date, an over-all suppression of phenotype. Pollen staining (Table 1) indicated no male pollen qualityhas beennotedin ourprogram. The reduction fertility, selfed seed were not obtained, and no seed were in stainable pollen (7 to 12%) was suspected at first, but has produced from backcross pollination with parent 82, even now been confirmed on cultivars, species, and hybrids though pegs and pods developed. No attemptswere made to analyzed before and after 1985. The reason for the lower culture the aborted embryos. Use of this pathway for counts has been identified and is beingverified, butwill not germplasm enhancement has not been reported. be presentedhere. Ifa conditions-induced reduction of7 to Pathway 3 12% is assumed on the BCs and BC pollen counts a Cuttings and seeds from the 34 X 37 hybrid plant were continuous increase in pollen stain for the six backcrosses treated with colchicine. Some of the resulting tetraploids wasobserved. Although pollen stain counts are not necessarily hadhigh levels of stainable pollen (Table 1), so crosses were the same as plant fertility, if used properly, they can be a attemptedwith parent82. Resultingprogenyweretetraploid relative measureofmale fertility. In thesestudies the absolute with varying levels ofpollen stainability (Table 1). Theplants percentage of pollen stainedwas not important because the appeared somewhat intermediate between wild and fertility levels were high enough after the BC3 generation to cultivated in early growth stages, but as they grew allowthe germplasm to be usedas a parentwith A. hypogaea they became progressively more like the wild type in for introgression ofdesirable traits. appearance. Fertilitywas low on all plants and no seedwere After five cycles of testinglbackcrossing in the above produced (Table 1). manner, seeds of BCsF2 families were increased for field These results on pathways 1 to 3 differ from those Table 2. A successful pathway for introgression from Arachis reportedby others (40,42). The difference is most likely due species to A hypogaea. to the use of differentA. hypogaea parents, althoughlocation Cross or Parent Number Plants Pollen Coynts· Seed set (latitude, elevation, climate) may have more effect than Backcross Number observed average range yes/no realized at the time these crosses were made. Existence of %% effects of differences in location were pointedoutby Stalker and Moss (40). Pathway 4 82X[19X(34X37)] c1.2 4 (group 3)3 27 24-32 Y Pathway 4 83X[19X(34X37)] c 4 (group 4) 30 27-31 Y The above approaches did not appear promising for the introgression of characters due to lack of fertility, so the 34 BC1 82 17 30 14-68 Y X 37 diploid hybrid was crossed with A. batizocoi. This (1979-1982) 83 37 40 09-79 Y approach (Pathway 4) had been proposed by Smartt et al BC 82 46 18-80 Y (34) as a solution to overcomingthe sterilitybarrierbetween 2 3 A. hypogaea and diploid species. Theyhypothesizedthatuse (1982-1983) 83 14 48 11-95 Y ofthe Bgenomeparentmight make the complexamphiploids more cross-compatiblewith A. hypogaea. Thediploidthree­ BC 3 82 18 74 59-85 Y way hybrid [19 X (34 X37)] was sterile (anticipated), an ideal (1983-1984) 83 56 72 32-96 Y situation for colchicine doubling. The induced tetraploid BC 4 82 12 73 64-84 Y expressed elevated hybridvigor, had 92% pollen stainability (1984-1985) 83 70 82 13-92 Y (Table 1), and was highly female fertile. The complex amphiploidwas hybridizedwith Tamnut 74 BC s 82 18 69 54-77 Y and the Florunner component line. The progeny expressed (1985-1986) 83 68 78 63-88 Y considerable hybridvigor, a moderate level ofpollen stained y (Table 1) and a low level of seed set. Backcrosses to the two BC e 82 20 75 68-80 A. hypogaea parents were accomplished readily. At this (1986-1987) 83 44 74 65-84 y stage, the first backcross Fl'Swere evaluated for early and late leafspot resistance. High levels of resistance to both • Percentage of stained (viable) pollen, rounded to whole numbers. 1 Parental numbers used to identify parents in program. diseases were present in all plants evaluated, indicating that 19=~~ (K-9484). the gene groups can be combined into one plant. Others 34=,8. ~ (GKP-10017). 37=,8. chacoensis (GKP-10602). have confirmed this conclusion (14, 37, 38, 40, 42). 82=,8. ~ var. ~ (Spantex through 1973). Recombination of the genes for resistance into the A. 82=,8. ~ var. ~ (Tamnut 74 after 1973). hypogaea cytoplasm has been confirmedby Ouedraogo (20) 83=,8. ~ var. ~ (UF-439-16-10-3-2, component line of Florunner). 2 Plant treated with colchicine to double the chromosome number. in BC derived from these lines. 3 A group represents 4 plants from one F • sF4's 1 INTROGRESSION IN ARACHIS 25 testing. Field evaluation ofthe BCsF 2 families indicated that 7. Gregory, W. C., B. W. Smith, and T. A.Yarbrough. 1951. Morphology, resistanceto leafspothadbeenintrogressedintoA. hypogaea. Genetics, and Breeding. pp. 28-88. in The peanut-the unpredictable Further evaluation of six of these lines (20) has confirmed legume. The Nat. Fertilizer Assoc. Washington, D. e. 8. Gregory, W. C., M. P. Gregory, A. Krapovickas, B. W. Smith, and J. A. introgressionofleafspotresistancegreaterthanthatexpressed Yarbrough. 1973. Structures and genetic resources of peanuts. pp. 47­ by the C. personatum resistant cultivar, 'Southern Runner' 133. in e. T. Wilson (ed.), Peanuts-Culture and Uses. Amer. Peanut (3). Res. and Educ. Assoc., Inc. Stillwater, OK. USA. Evaluatingthis program in light ofthe available literature 9. Jackson, L. F. 1983. Relative susceptibilities of component lines of peanutcultivars Early Bunch and Florunnertoearly and late leafspots. (e.g., 40, 42) points out the reason for lack ofhigh levels of Peanut Sci. 10:3-5. leafspot resistance. The characters ofearly and late leafspot 10. Johansen, D. A. 1940. Plant Microtechnique. McGraw-Hill Book Co., are apparently multigenic with the strong possibility that Inc. New York and London. each character is controlled by two or more genes. Thus the 11. Knauft, D. A.,D. W. Gorbet, andA. J. Norden. 1988.Yieldand market testing and backcrossing should have been conducted on quality of seven peanut genotypes as affected by leafspot disease and harvest date. Peanut Sci. 15:9-13. BCnF2's or BC F 's rather than BCnF1's.The characters can 12. Krapovickas,A.1969.The origin,variabilityandspreadofthegroundnut be introgressed through pathway 4 (20), but the time factor (Arachis hypogaea). pp. 427-440. in P. J. Ucko and G. W. Dimbelby will be important because selections for backcrossing will (eds.), The domestication and exploitation of plants and animals. have to be made after testing and from later generations. Duckworth. London. 13. Melouk, H. A.,and D. J. Banks. 1978. A method for screening peanut Cuttingswere maintainedofalmost allgenerations (some genotypes for resistance to Cercospora leafspot. Peanut Sci. 5:112­ cuttings died), andretestingofthese materials indicatedthat 114. the resistance to three diseases (early and late leafspot and 14. Moss, J. P., 1. V. Spielman, A. P. Burge, A. K. Singh, and R. W. Gibbons. 1981. Utilization of wild Arachis species as a source of southern root-knot nematode) was contained in the BC F1 material (15,20 and unpublisheddata). Backcrossing to that Cercospora leafspot resistance in groundnut breeding. pp. 673-677. in G. K. Marna and U. Sinha (eds.), Perspectives in cytologyand genetics. generation followed by testing of BC nF2's (or later Hindasia Publ. Delhi, India. generations) should result in development of leafspot 15. Nelson, S. c., e. E. Simpson, and J. L. Starr. 1989. Resistance to resistant/root-knot nematode resistant germplasm that is Meloidogyne arenaria in Arachis spp. germplasm. Supp. J. of highly compatible with A. hypogaea. Nematology 21:654-660. 16. Norden, A. J., R. W. Lipscomb, and W. A. Carver. 1969. Registration of Florunner peanuts. Crop Sci. 9:850. Conclusions 17. Norden, A. J. 1980. Chapter 31 - Peanut. pp. 443-453. in W. R. Fehr Conclusions drawn from these andthe relatedstudies are and H. H. Hadley (eds.), Hybridization of Crop Plants. Amer. Soc. of Agron. Crop. Sci. Soc. of Amer. Madison, WI. USA. as follows: 18. Norden, A. J. 1973. Breeding of the cultivated peanut (Arachis 1. Hybrids between A and B genome Arachis parents hypogaea L.). pp. 175-208. in e. T. Wilson (ed.), Peanuts-Culture appear to be useful for introgressing characters into A. and Uses. Amer. Peanut Res. and Educ. Assoc., Inc. Stillwater, OK. hypogaea from wild Arachis species. USA. 2. B genome A. batizocoi can serve as an effective bridge 19. Norden, A. J., O. D. Smith, and D. W. Gorbet. 1982. Breeding of the cultivated peanut. pp. 95-122. in H. E. Pattee and e. T. Young (eds.), species between A genome wild Arachis and A. hypogaea. Peanut Science and Technology. Amer. Peanut Res. and Educ. Soc. 3. The results support the hypothesis that leafspot Yoakum, TX. USA. resistance is multigenic. 20. Ouedraogo, M. 1990.Yield,grade, and leafspot reaction ofinterspecific 4. Leafspot resistant/root-knot nematode resistant derived peanut lines. M. S. Thesis 92 pp. Soil and Crop Sci. Dept. Texas A&M Univ., College Station, TX 77843. cultivars of peanut should be possible by introgression of 21. Porter, D. M., D. H. Smith, and R. Rodriguez-Kabana. 1982. Peanut genes from wild peanut species into A. hypogaea. diseases. pp. 326-410. in H. E. Pattee and C. T. Young (eds.), Peanut Science and Technology. Amer. Peanut Res. and Educ. Soc. Yoakum, Acknowledgments TX. USA. 22. Sharief, Y., J. O. Rawlings, and W. C. Gregory. 1978. Estimates of The author thanks W.e. Gregory and M.P. Gregory for stimulating his leafspot resistance in three interspecific hybrids of Arachis. Euphytica interest in this program, and he gratefully acknowledges the technical 27:741-751. assistance of Wm. H. Higgins, Jr., K.E. Woodard, D.L. Higgins, K.S. 23. Simpson, C. E. and O. D. Smith. 1975. Registration of Tamnut 74 Davis, and numerous Tarleton State University students. Also, the Peanut. Crop Sci. 15:603-604. encouragementand adviseofO.D. SmithandJ.S. Newman isacknowledged. 24. Simpson, C. E. and K. S. Davis. 1983. Meiotic behavior of a male­ fertile triploid Arachis L. hybrid. Crop Sci. 23:581-584. 25. Simpson, C. E. 1984. Plant Exploration: planning, organization, and Literature Cited implementation with special emphasis on Arachis. pp. 1-20. in W. L. Brown,T.T. Chang, M. M.Goodman, and Q.Jones (eds.),Conservation 1. Abdou, Y. A-M., W. e. Gregory, W. E. Cooper. 1974. Sources and of Crop Germplasm-An International Perspective. Crop Sci. Soc. of Nature of resistance to Cercospora arachidicola Hori. and Amer. Madison WI. USA. Cercosporidium personatum (Beck and Curtis) Deighton in Arachis 26. Singh, A.K.and J. P. Moss. 1982.Utilization ofwild relatives in genetic species. Peanut Sci. 1:6-11. improvement of Arachis hypogaea L. Part 2. Chromosome 2. Banks, D. J. 1977. A colchicine method which achieves fertility in complements of species in section Arachis. Theor. Appl. Genet. interspecific peanut hybrids. Proc. Amer. Peanut Res. and Educ. 61:305-314. Assoc. 9:30 (Abstr.). 27. Singh, A.K.and J. P. Moss. 1984. Utilization ofwild relatives in genetic 3. Gorbet, D. W., A. J. Norden, and F. M. Shokes. 1987. Registration of improvement of Arachis hypogaea L. VI. Fertility in Triploids: 'Southern Runner' peanut. Crop Sci. 27:817. Cytological basis and breeding implications. Peanut Sci. 11:17-21. 4. Gregory, M. P., and W. e. Gregory. 1979. Exotic germ plasm of 28. Singh, A.K. 1986a. Alien gene transfer in groundnut by ploidy and Arachis L. interspecific hybrids.]. Hered. 70:185-193. genome Manipulations. pp. 207-209. in Horn, Jensen, Odenbach, and 5. Gregory, W. C. 1945. Research and Farming. pp. 33-35. 68th Ann. Schieder (eds.), Genetic Manipulation in Plant Breeding. Walter de Rpt. N. e. Agric. Exp. Stn. N. C. State Univ. Raleigh, N. C. USA. Gruyter and Co. Berline , New York. 6. Gregory, W. C. 1946. Peanut Breeding Program underway. pp. 42-44. 29. Singh, A. K. 1986b. Utilization of wild relatives in the genetic Research and Farming. 69th Ann. Rpt. N. e. Agric. Exp. Stn. N. C. improvement of Arachis hypogaea L. 7. Autotetraploid production State Univ. Raleigh, N. C. USA. and prospects in inter-specific breeding. Theor. Appl. Genet. 72:164- 26 PEANUT SCIENCE

169. Reporter 60:494-498. 30. Singh, A. K. 1986c. Utilization of wild relatives in the genetic 36. Spielman, I. V., A.P. Burge, and J.P. Moss. 1979. Chromosome loss improvement of Arachis hypogaea L. 8. Synthetic amphidiploids and and meiotic behaviour in interspecific hybrids in the genus Arachis L. theirimportancein interspecific breeding. Theor. Appl. Genet. 72:433­ and their implications in breeding for disease resistance. Z. 439. Pflanzenzuchtg 83:236-250. 31. Singh, A. K. 1988. Putative genome donors of Arachis hypogaea 37. Stalker, H. T. andJ. C. Wynne. 1979. Cytologyofinterspecific hybrids (), evidence from crossess with synthetic amphidipolids. in section Arachis of peanuts. Peanut Sci. 6:110-114. Plant Syst. and Evol, 160:143-151. 38. Stalker, H. T, J. C. Wynne, and M. Company. 1979. Variation in 32. Smartt, J. 1965. Cross-compatibility relationships between the progenies of an Arachis hypogaea X diploid wild species hybrid. cultivated peanut Arachis hypogaea L. and other species of the genus Euphytica 28:675-684. Arachis. Ph.D Thesis, North Carolina State Univ., Raleigh. Univ. 39. Stalker, H. T and R. D. Dalmacio. 1981. Chromosomes of Arachis Microfilms Int. Ann Arbor Mich. (Diss. Abstr. 65:8968). species, section Arachis. J. Hered. 72:403-408. 33. Smartt, J.W. C. Gregory, and M. P. Gregory. 1978. The genomes of 40. Stalker, H. T and J. P. Moss. 1987. Speciation, Cytogenetics, and Arachis hypogaea 1. Cytogenetic studies of putative genome donors. Utilization of Arachis Species. Adv. in Agron. 41:1-40. Euphytica 27:665-675. 41. Subrahmanyam, P., D. McDonald, R. W. Gibbons, S. N. Nigam, and 34. Smartt, J., W. C. Gregroy, and M. P. Gregory. 1978. The genomes of D. J. Nevill. 1982. Resistance to rust and late leafspot diseases in some Arachis hypogaea 2. The implications in interspecific breeding. genotypes of Arachis hypogaea. Peanut Sci. 9:6-10. Euphytica 27:677-680. 42. Wynne, J. C. and T. Halward. 1989. Cytogenetics and Genetics of 35. Sowell,G., Jr., D. H. Smith, and R. O. Hammons. 1976. Resistance of Arachis. Critical Reviews in Plant Sciences 8:189-220. peanut plant introductions to Cercospora arachidicola. Plant Disease Accepted February 8,1991

Peanut Science (1991) 18:26-30