Peanut Science (1981) 8, 45-47 Resistance to Peanut Stunt Virus in Cultivated and Wild Arachis Species T. T. Herbert* and H. T. StalkeP ABSTRACT Table 1. Wild Arachis collections without symptoms or virus recovery during two tests for peanut stunt virus. Approximately 4OOO lines (cultivars, introductions, breeding No. Collection no. lines, and radiation-induced mutants) of cultivated peanuts (Ara- Section PI number chis hypogaea L.) were tested for resistance to peanut stunt virus or species name ~ollector~ (PSV), and all were susceptible to PSV infection. Twenty-one 1. 9571 GKP !hi zomatosae 262818 lines were less severely damaged than the others. In addition, 2. 96108 GKP 262832 90 3. 9806 GKP 262792 collections of wild Arachis species including 55 members of sec- 4. 9813 GKP ,I 262793 tion Rhizomatosae, 17 ofArachis, 16 of Erectoides, and one each 5. 9827 GKP 4, 262796 6. 9921 GKP 262296 of Caulorhizae and Extranervosae were tested. Several collec- 7. A. labrata 61 -- ,I -- tions in sections Arachis, Caulorhizae, Erectoides and Rhizoma- 8. n6k- -- I -- 9. 9644 GKP #I 26 2840 tosae were highly resistant to PSV. Collections ofA. duranensis, 10. 9649 GKP 262844 A. villosa, and a hybrid derivative ofA. villosa-A. correntina have 11. 9822 GKP 262795 the most immediate potential for utilization. The reactions of a 12. 9922 GKP 13. 9925 GKP few F, hybrids ofArachis species indicated that resistance to pea- 14. 9935 GKP I, nut stunt virus is not conditioned by a single dominant gene. Res- 15. 10105 GKP I4 276200 16. 10596 GK 276233 istance of wild species could be used to develop resistant cultiv- 17. 210 -- 261851 /261876 ars . 18. 1960 #3 -- 19. 1960 #8 -- 6, 20. 1960 1100 -- 21. 7988 K Arachis -- Key Words: Groundnut, Arachis hypogaea, peanut stunt virus. 22. 9553 GKP Rhi zoma tosae 262801 23. 9564 GKP I 26281 1 24. 9568 GKP #I 262815 25. 9569 GKP 262816 26. 9570 GKP 262817 When the peanut stunt virus disease was first observed 27. 9574 GKP 262820 28. 9576 GKP I, 262822 in North Carolina and Virginia, it was regarded as a se- 29. 9580 GKP 8, 262825 30. 9587 GKP 262826 rious threat to peanut (Arachis hypogaea L.) production in 31. 9591 GKP I 262827 that region. Almost total destruction of the crop occurred 32. 9618 GKP 8, 262833 33. 9634 GKP in severely affected portions of some fields (2, 6). 34. 9764 GKP Erectoides 35. 9797 GKP Rhi zomatosae 36. 9815 GKP II 262794 37. 9893 G KP 262287 Although peanut stunt virus (PSV)can infect many spe- 38. 9966 GKP 262306 cies of leguminous and solanaceous plants, as well as a few 39. 10120 GKP ,I 276202 40. 10543 GK Erectoi des 276209 species in other plant families (5, 7), the virus seems to 41. 10550 GK rlhizomatosae 42. 10566 GK 276223 persist almost exclusively in white clover (TriXolium rep- 43. 10573 GK Erectoides 276225 ens in North Carolina. Other species (Trifolium pra- 44. 10580 GK )I 276229 L.) 45. 10598 -- Arachi s 276234 tense L., Pueraria thunbergiana (Seib. & Zucc.) Benth, 46. 22585 B II 298636 47. Manfredi #5 -- ,I -- Solanum carolinense L., and species ofLespedeza and Vi- 48. A. repens -- Caulorhi zae cia) are sometimes naturally infected with PSV but are not aAbbreviation of collectors' names: B = Burkart, G = Gregory, H = important sources of inoculum. If PSV strains which are Hamnons, K = Krapovickas, P = Pietrarelli. better adapted to other hosts should develop, the disease could become a serious problem. Introduction of PSV in- to countries with existing host plants could result in se- rolina State University. Additionally, some lines of cultivated peanuts and collections of wild Arachis species were obtained from the United rious PSV epidemics. Also, PSV could assume greater im- States Department of Agriculture. portantance in areas more favorable for secondary spread of the virus. As part of a program to find effective control To evaluate resistance to PSV, young seedlings or cuttings were inoc- measures for this disease, cultivated peanuts and wild ulated one to three times with juice from infected beans, cowpeas, or peanuts extracted in 0.05M phosphate buffer (pH 7.5) containing0.01M Arachis species were screened for resistance to PSV. sodium diethyldithiocarbamate. Inoculum containing 1 g of 600 mesh Carborundum per 100 ml ofbuffered plant extracts was applied to plants with an artist's airbrush or with a cotton swab. Plants with symptoms 6 Materials and Methods weeks after inoculation were discarded. Plants without symptoms were pruned and fertilized to regenerate new growth. Plants with symptoms The lines of cultivated peanuts and wild species (Tables 1, 2) tested on the new foliage were then discarded and the remaining symptomless were primarily those in the large collection of cultivars, breeding lines, plants were re-inoculated. After an additional 6 weeks, plants without introductions, and radiation-induced mutants maintained at North Ca- symptoms were serologically tested for the presence of the virus or by inoculation of beans or cowpeas with juice extracted from these plants. If 'Paper No. 6783 of the Journal Series of the North Carolina Agricultu- PSV was not detected, cuttings were made from the plants and inocula- ral Research Service, Raleigh, NC 27650. Financial support from the tion was repeated on new cuttings. United States Department of Agriculture and contributions of plant ma- terials and valuable advice by Dr. w. C. Gregory are gratefully acknowl- Some lines that were not infected in the mechanical inoculation tests edged. were further tested by grafting infected scions onto cuttings or seedlings of the apparently resistant lines. These were then observed for develop- 'Professor Emeritus, Department of Plant Pathology, and Assistant ment of symptoms and tested for the presence of the virus as described Professor, Department of Crop Science, N. C. State University, Ra- above. Selected lines were also tested for susceptibility to PSV in a field leigh, NC 27650, respectively. near infected white clover. 45 46 PEANUTSCIENCE Table 2. Reaction of susceptible Arachis collections to peanut stunt vi- Collections of wild Arachis species exhibiting no symp- rus. toms after three inoculations varied as to presence or ab- sence of PSV. Of the 76 collections without symptoms, Rati ngsb Collection col let- Test 2 PSV was not detected in 66 collections (Tables 1, 2, Test no. or Section PI number Symp-Test Virus' Symp- Virus species name tors toms recov. toms recov. l),while PSV was detected in inoculated leaves in only five collections, and from systemically invaded leaves in 9566A GKP R hizana tosae 262812 002- 9578 G KP I 262824 002- five other collections (Table 2, Test 1).New cuttings of the 9667 GKP I# 262848 002- 9830 G KP ,I 262797 002- 76 collections without symptoms in the first test were in- 9882 GKP I 262286 002- oculated at least three additional times and tested for the 9990 GKP Erectoides 261853/261877 '0 0 2 - 10574 -- I, 276226 002- presence of PSV. PSV was not detected in 56 of these col- 10585 GK 8, 276231 002- -~A. correntina -- Arachis -- 002- lections (Tables 1,2, Test 2). Grafts of scions from infected 6. glabyata !hi zomatosae -- 002- peanuts were established on of these lines, and none A. marginata -- -- 002- 16 9629 GKP 262834 003- developed symptoms of PSV (Table 1, nos. 1-16). Seven of 9893 G KP 262287 003- A 23 H -- 003- the grafted lines were also assayed for the presence of 9645 GKP 262841 004- 9834 GKP 262798 004- PSV, and virus was not detected (Table 1, nos. 1-7). Res- 10017 GKP Arachi s 262141 9835 G KP Erectoides 262308 istance to PSV was present in four of the five observed bo- 7897 K Arachis 261868/262134 tanical sections of the genus Arachis, including sections 9548 GKP II 262839/262873 11462 KFC Erectoides -- Arachis, Caulorhizae, Erectoides and Rhizomatosae. Manfredi #8 -- Arachis Manfredi #36 -- 8, -- 7830 K 8, 261871/262137 In addition to the original collections, 11 F1 interspecif- 9530 GKP I' 262808 osoo 9642 GKP Rhizomatosae 262839/262873 0 S 0 0 ic hybrids were evaluated for resistance to PSV (Table 3). 9646 GKP Erectoides 262842/262874 0 S 0 0 9769 GKP 262862 osoo The reactions indicated that resistance to PSV is not con- 9841 GKP " 262278 2- 10038 GKP Arachis 262133 2- ditioned by a single dominant gene and is probably multi- 9645 GKP Rhi zomatosae 262841 3- genic in nature. This will increase the difficulty of select- 10034 GKP Erectoides 261875/262142 3 - 11488 KC - -- 3- ing homozygous-resistant genotypes. 10127 GKP Extranervosae 276203/276309 4 - -~A. monticola -- !rachis -- 4- ...A villnca......*" -- ' _- A- 95668 GKP Rhizomatosae 262813/262871 4 - The potential for utilizing PSV-resistant wild species is 10602 GKP Arachis 276235 5- great. However, utilization of this germplasm is restrict- 9572 GKP Rhizomatosae 262819 6- 9825 GKP Erectoides 263105 6- ed by our inability to obtain hybrids among most Arachis 10576 GK )I 276228 8- species and A. hypogaea (4). For example, members of sections Caulorhizae, Erectoides, and Rhizomatosae 'Abbreviation of collectors' names: B = Burkart, C = Cristobal, F = Fugaratzo, G = Gregory, H = Hamnons, K = Krapovickas, P = Pietrarelli. (three of the four sections where PSV-resistant species bSymptoms: 0 = none, 1-2 = mild, 3-5 = moderate, 6-9 = severe. Virus was found) will not hybridize with the cultivated peanut. recovery: 0 = no virus, L = virus recovered from inoculated leaves only, S = virus recovered fran systemically invaded leaves. Although PSV-resistant members of section Arachis are at a diEerent ploidy level than A. hypogaea, the cultivated Results and Discussion and wild species are cross-compatible (4, 8). The most promising wild species for developing PSV-resistant pop- Greenhouse inoculation tests demonstrated that pea- ulations are A.