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PLANT GENETIC RESOURCES

Evaluation of the Core Collection Approach for Identifying Resistance to Meloidogyne arenaria in Peanut

^a USDA-ARS, P. O. Box 748, Coastal Plain Exp. Stn., Tifton, GA 31793 USA
^b Shandong Peanut Res. Inst., Shandong, People's Republic of China

holbrook{at}tifton.cpes.peachnet.edu

	ABSTRACT

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
Core collections are representative subsamples of germplasm collections. Use of core collections may improve the efficiency of germplasm evaluations by reducing the number of accessions evaluated while increasing the probability of finding genes of interest. The peanut (Arachis hypogaea L.) core collection has been examined for resistance to the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1]. Resistant indicator accessions from screening the core collection identified 39 clusters in the entire germplasm collection that should be examined more thoroughly. The objective of this study was to evaluate how effective a two-stage core screening approach would be in identifying resistance to M. arenaria in the entire U.S. germplasm collection of peanut. Accessions from 30 clusters having resistant indicator accessions and from four clusters having very susceptible indicator accessions were tested for resistance in two greenhouse trials. This second stage screening identified 259 accessions that had a mean egg-mass rating of 2.5 or less. Twenty-eight of these accessions had a mean egg-mass rating of 1.0 or less. There were relatively large numbers of resistant accessions from China and Japan compared with the percentages of the germplasm collection that originated from these countries. The efficiency of identifying accessions resistant to M. arenaria was greater in clusters having resistant indicator accessions than in clusters having susceptible indicator accessions. These results demonstrate that the use of a two-stage screening approach with a core collection can improve the efficiency of identifying valuable genes in germplasm collections.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
THE DEVELOPMENT OF CORE COLLECTIONS has been proposed as a way to increase the efficiency of maintenance and evaluation of germplasm collections (Frankel, 1984; Frankel and Brown, 1984). The core collection approach for germplasm evaluation is a two-stage approach. The first stage involves examining all accessions in the core collection. This information is then used to determine which additional accessions in the entire germplasm collection should be examined during the second stage of screening.

A core collection has been selected to represent the U.S. germplasm collection of A. hypogaea (Holbrook et al., 1993). To select this core collection, the entire collection was first stratified by country of origin and then divided into nine sets on the basis of the amount of additional information available for accessions and on the number of accessions per country of origin. Seventy percent of this core collection (Sets 4–8) was selected by stratification by country of origin before using multivariate analysis on morphological data to cluster accessions into groups and then randomly sampling 10% from each group. Because of the lack of morphological data for some accessions, 29% of this core collection (Sets 2, 3, and 9) was selected using a 10% random sample after stratifying by country of origin. The remaining 1% (Set 1) was a simple random sample.

The development of this core collection has stimulated a great deal of germplasm evaluation in peanut. The core collection has been evaluated for percentage oil content (Holbrook et al., 1998), fatty acid composition (Hammond et al., 1997), and for resistance to tomato spotted wilt virus (TSWV) (Anderson et al., 1996), early leaf spot (Cercospora arachidicola S. Hori) and Cylindrocladium black rot [Cylindrocladium crotalariae (C.A. Loos) D.K. Bell & Sobers] (Isleib et al., 1995), Rhizoctonia limb rot (Rhizoctonia solani Kühn) (Franke et al., 1999), and preharvest aflatoxin contamination (Aspergillus spp.) (Holbrook et al., 1997). However, none of these studies involved second-stage screening of the indicated accessions in the entire collection.

The peanut core collection has also been examined for resistance to the peanut root-knot nematode (Holbrook et al., 2000). Resistant indicators from screening the core collection identified 39 clusters in the entire U.S. germplasm collection that should be examined more thoroughly. The objective of this study was to evaluate how effective a two-stage core screening approach would be in identifying resistance to M. arenaria race 1 in the U.S. peanut germplasm collection.

	Materials and methods

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
Seeds for all accessions in 30 clusters having resistant indicator values were obtained from the USDA Southern Regional Plant Introduction Station, Experiment, GA. Seeds were also obtained for all accessions in four clusters having very susceptible indicator values. There were 394 accessions from clusters having a resistant indicator value and 121 accessions from the clusters having susceptible indicator values.

Accessions were tested for resistance to M. arenaria race 1 using the greenhouse screening technique described by Holbrook et al. (1983). Accessions were planted in the greenhouse in a randomized complete block design with four replications on 5 Dec. 1997 and 8 June 1998 for Trial 1 and 2, respectively. Plants were grown in steam-pasteurized loamy sand (85% sand, 11% silt, 4% clay). Each pot was inoculated with 3500 eggs of M. arenaria race 1 that had been cultured on tomato (Lycopersicon esculentum Mill. cv. Rutgers). Nematode inoculum was prepared using the NaOCl method (Hussey and Barker, 1973), and applied 14 d after planting.

Approximately 90 d after inoculation, plant roots were washed clean of soil. The roots were placed in 1000-mL beakers containing 300 mL of phloxine B solutions for 3 to 5 min (Daykin and Hussey, 1985). Each root system was indexed for galls and egg masses based on the following scale: 0 = no galls or egg masses, 1 = 1 to 2, 2 = 3 to 10, 3 = 11 to 30, 4 = 31 to 100, 5 = more than 100 galls or egg masses per root system (Taylor and Sasser, 1978).

Data were subjected to analysis of variance. Means for egg-mass ratings were calculated and resistance was defined as a mean rating of 2.5 or less. Previous research has shown that progress can be made using a mean egg-mass rating of 3.0 or less as the selection criteria (Holbrook and Noe, 1992; Holbrook et al., 1996). We decided to use a slightly more stringent selection criteria in this study to focus our efforts on the most resistant accessions. Success rates [(number of resistant accessions identified/total number of accessions screened)100] were calculated for various subsets of the entire collection. Comparisons of success rates were made by calculating chi-square values with contingency tables. The Yates correction term was used since this adds to the accuracy of chi-square analyses when the number of an expected class is small (Strickberger, 1976).

	Results and discussion

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
Analysis of variance showed a nonsignificant entry x trial interaction, so the data from the two trials were pooled. Second-stage screening identified 259 accessions that had a mean egg-mass rating of 2.5 or less (Table 1) . Twenty-eight of these accessions had a mean egg-mass rating of 1.0 or less. During screening of the core collection, Holbrook et al. (2000) observed that a large proportion of resistant accessions originated from China relative to the percentage of the germplasm collection that originated from that country. Seventy-seven of the 259 accessions with an egg-mass rating of 2.5 or less and eight of the 28 accessions with an egg-mass rating of 1.0 or less were from China. This confirms the observation of Holbrook et al. (2000) that China is a valuable source for peanut germplasm with resistance to M. arenaria. Although peanut is not native to China, it has been widely cultivated in China for several centuries (Hammons, 1982), and M. arenaria is an important pathogen of peanut in China (Minton and Baugard, 1990).

View this table: [in this window] [in a new window]   Table 1 Peanut plant introductions with resistance (defined as a mean egg-mass rating of 2.5 based on data from two greenhouse trails) to the peanut root-knot nematode (Meloidogyne arenaria) identified by use of a two-stage core collection screening approach

The peanut core collection was selected using all available information from the germplasm resource information network (Holbrook et al., 1993). Sets 4 through 8 were randomly selected after grouping by country of origin and clustering by multivariate analysis. Due to a lack of morphological data, Sets 2, 3, and 9 were randomly sampled after grouping by country of origin. Because of the low number of accessions for some countries of origin, Set 1 was a random sample. The success rate for material in Sets 4 through 8 was not significantly different from that in Sets 2 and 3, which were selected after stratifying by country of origin only (Table 4) . This is in contrast to the observations of Holbrook and Anderson (1995) of a higher success rate for identifying resistance to late leaf spot from groups made by clustering on previous descriptor information in comparison with the success rate from groups obtained merely by sampling randomly within countries of origin. This difference may be an artifact caused by the selection of material that would undergo second-stage screening for resistance to M. arenaria. The leaf spot study used data on leaf spot resistance for the entire collection to retrospectively determine how effective a two-stage core screening approach would have been in identifying sources of resistance. In the present study we chose three relatively small groups of accessions from Sets 2 and 3 for inclusion in the second-stage screening. Other larger groups of accessions from Sets 2 and 3 with resistant indicator accessions were not included. The inclusion of these larger groups may have reduced the success rate for material from Sets 2 and 3.

	ACKNOWLEDGMENTS

 
The contributions and technical support of Jamie Day, Vickie Hogan, Dannie Mauldin, and Betty Tyler are gratefully acknowledged. This work was supported in part by funds from The Peanut Foundation and the Georgia Peanut Commission.

Received for publication July 29, 1999.

	REFERENCES

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 

• Anderson W.F., Holbrook C.C., Culbreath A.K. Screening the peanut core collection for resistance to tomato spotted wilt virus. Peanut Sci. 1996;23:57-61.
• Daykin, M.E., and R.S. Hussey. 1985. Staining and histopathological techniques in nematology, p. 39–48. In K.R. Barker, et al. (ed.) An advanced treatise on Meloidogyne. Vol. II: Methodology. North Carolina State Univ., Raleigh.
• Franke M.D., Brenneman T.B., Holbrook C.C. Identification of resistance to Rhizoctonia limb rot in a core collection of peanut germplasm. Plant Dis. 1999;83:944-948.
• Frankel O.H. Genetic perspectives of germplasm conservation. In: Arber W.K., et al. , ed. Genetic manipulation: Impact on man and society. Cambridge, UK: Cambridge Univ. Press, 1984:161-170.
• Frankel, O.H., and A.H.D. Brown. 1984. Current plant genetic resources—A critical appraisal. p. 1–11. In Genetics: New Frontiers Vol. IV. Oxford and IBH Publ. Co., New Delhi.
• Isleib T.G., Beute M.K., Rice P.W., Hollowell J.E. Screening the core collection for resistance to Cylindrocladium black rot and early leaf spot. Proc. Am. Peanut Res. Educ. Soc. 1995;27:25.
• Hammond E.G., Duvick D., Wang T., Dodo H., Pittman R.N. Survey of fatty acid composition of peanut (Arachis hypogaea) germplasm and characterization of their epoxy and eicosenoic acids. J. Am. Oil Chem. Soc. 1997;74:1235-1239.[ISI]
• Hammons R.O. Origin and early history of the peanut. In: Pattee H.E., Young C.T., eds. Peanut science and technology. Yoakum, TX: Am. Peanut Res. Educ. Soc, 1982:1-20.
• Holbrook C.C., Anderson W.F. Evaluation of a core collection to identify resistance to late leaf spot in peanut. Crop Sci. 1995;35:1700-1702.[Abstract/Free Full Text]
• Holbrook C.C., Anderson W.F., Pittman R.N. Selection of a core collection from the U.S. germplasm collection of peanut. Crop Sci. 1993;33:859-861.[Abstract/Free Full Text]
• Holbrook, C.C., J. Bruniard, K.M. Moore, and D.A. Knauft. 1998. Evaluation of the peanut core collection for oil content. p. 159. In Agronomy Abstracts. ASA, Madison, WI.
• Holbrook C.C., Knauft D.A., Dickson D.W. A technique for screening peanut for resistance to Meloidogyne arenaria. Plant Dis. 1983;67:957-958.
• Holbrook C.C., Noe J.P. Resistance to the peanut root-knot nematode (Meloidogyne arenaria) in Arachis hypogaea. Peanut Sci. 1992;19:35-37.
• Holbrook C.C., Noe J.P., Stephenson M.G. Identification and evaluation of additional sources of resistance to peanut root-knot nematode in Arachis hypogaea L. Peanut Sci. 1996;23:91-94.
• Holbrook C.C., Stephenson M.G., Johnson A.W. Level and geographical distribution of resistance to Meloidogyne arenaria in the U.S. germplasm collection of peanut. Crop Sci. 2000;40:1168-1171 (this issue).[Abstract/Free Full Text]
• Holbrook, C.C., D.W. Wilson, and M.E. Matheron. 1997. Results from screening the peanut core collection for resistance to preharvest aflatoxin contamination. In J. Robens and J. Dorner (ed.) Proc. Aflatoxin Elimination Workshop. Memphis, TN. 27–28 Oct. 1997. USDA-ARS, Beltsville, MD.
• Hussey R.S., Barker K.R. A comparison of methods of collecting inocula for Meloidogyne spp., including a new technique. Plant Dis. Rep. 1973;57:1025-1028.
• Minton, N.A., and P. Baujard. 1990. Nematode parasites of peanut. p. 285–320. In M. Luc, et al. (ed.) Plant parasitic nematodes in subtropical and tropical agriculture. CAB Int., Wallingford, UK.
• Strickberger M.W. Genetics, 2nd ed New York: Macmillan, 1976.
• Taylor A.L., Sasser J.N. Biology, identification and control of root-knot nematodes (Meloidogyne species). Raleigh: North Carolina State Univ, 1978.

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This Article Abstract Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Holbrook, C.C. Articles by Xue, H.Q. Search for Related Content PubMed Articles by Holbrook, C.C. Articles by Xue, H.Q. Agricola Articles by Holbrook, C.C. Articles by Xue, H.Q.