HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

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 (11) Citing Articles via Google Scholar Google Scholar Articles by Holbrook, C.C. Articles by Johnson, A.W. Search for Related Content PubMed Articles by Holbrook, C.C. Articles by Johnson, A.W. Agricola Articles by Holbrook, C.C. Articles by Johnson, A.W.

PLANT GENETIC RESOURCES

Level and Geographical Distribution of Resistance to Meloidogyne arenaria in the U.S. Peanut Germplasm Collection

USDA-ARS, P.O. Box 748, Coastal Plain Exp. Stn., Tifton, GA 31793 USA

holbrook{at}tifton.cpes.peachnet.edu

	ABSTRACT

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
The peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] causes significant economic losses in many peanut (Arachis hypogaea L.) production areas of the world. The objectives of this study were (i) to examine the peanut core collection to identify sources of resistance, (ii) to estimate the level of resistance that occurs in the U.S. germplasm collection, and (iii) to examine the geographical distribution for resistance in peanut germplasm. Seven hundred forty-one accessions from the core collection were tested in greenhouse trials. The egg-mass rating for cultivar Florunner, the susceptible check, was 4.0 on a 1.0 to 5.0 scale with a nematode reproduction rate of 15496 eggs per gram of fresh root weight. Fifty-six accessions exhibited an egg-mass rating of 2.5. Thirty-six core accessions showed a reduction in root galling, egg-mass rating, egg count per root system, and egg count per gram of root in comparison to Florunner. Twenty-one accessions showed a 70% reduction in egg count per root system and per gram of root, and two accessions showed a 90% reduction of these variables in comparison with Florunner. The 56 resistant indicators from screening the core collection identified 39 clusters in the entire germplasm collection that should be examined more thoroughly. China and Japan appear to be valuable geographical sources for resistance to this nematode.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
THE ROOT-KNOT NEMATODE causes significant economic losses in many peanut production areas of the world. Chemicals for control of this pest are becoming increasingly limited, and the development of peanut cultivars with resistance would be desirable.

Only moderate levels of resistance have been observed in naturally occurring germplasm of A. hypogaea. Holbrook and Noe (1992) evaluated 1321 peanut plant introductions for resistance to M. arenaria and identified 17 accessions that supported fewer egg masses and seven genotypes that supported less egg production per gram of fresh root weight compared with the cultivar Florunner. Holbrook et al. (1996) evaluated 1000 plant introductions and identified eight additional accessions that had significantly higher levels of resistance (lower egg mass rating) than Florunner. Although none of the eight had a significantly higher level of resistance than those reported by Holbrook and Noe (1992), two of the eight exhibited significantly higher yield than all others when grown in soil heavily infested with M. arenaria.

More desirable sources of resistance to M. arenaria may exist in A. hypogaea since less than one-third of the germplasm collection has been examined for resistance based on nematode reproduction. A core collection has been selected to represent the U.S. germplasm collection of peanut (Holbrook et al., 1993). Theoretically this core collection could be used to more efficiently identify desirable traits, such as nematode resistance, in the entire collection (Brown, 1989; Frankel, 1984). Data on resistance to late leaf spot [Phaeoisariopsis personata (Berk. & M.A. Curtis) Arx. syn. Cercosporidium personatum (Berk. & M.A. Curtis)] for the entire collection was used to empirically evaluate the peanut core collection (Holbrook and Anderson, 1995). The results demonstrated that the use of the peanut core collection would have improved the efficiency of identifying resistance to late leaf spot in the entire collection.

Very high levels of resistance to M. arenaria exist in related Arachis spp. (Nelson et al., 1989; Holbrook and Noe, 1990). The level of resistance thus far observed in A. hypogaea has not been as high as that observed in wild species or interspecific material derived from these species. Screening of the peanut core collection should indicate whether high levels of resistance to M. arenaria occur in A. hypogaea.

The objectives of this study were (i) to use the core collection to identify sources of resistance (ii) to estimate the level of resistance available in the germplasm collection of A. hypogaea, and (iii) to examine the geographical distribution for resistance in peanut germplasm to indicate areas within the collection for further study.

	Materials and methods

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
The peanut core collection consists of 831 accessions (Holbrook et al., 1993). Seed was available for 741 accessions, and these accessions were tested for resistance to M. arenaria by the greenhouse screening technique described by Holbrook et al. (1983) with five replications (5 plants). Plants were grown in steam-pasteurized loamy sand (85% sand, 11% silt, 4% clay). Each plant was inoculated with 3500 eggs of M. arenaria race 1, which had been cultured on tomato (Lycopersicon esculentum Mill. cv. Rutgers). Nematode inoculum was prepared using the NaOCl method (Hussey and Barker, 1973) and applied 10 d after planting.

Approximately 90 d after inoculation, plants were uprooted and washed clean of soil. The roots were placed in 1000-mL beakers containing 300 mL of phloxine B solution for 3 to 5 min (Daykin and Hussey, 1985). Each plant was indexed for root galls and egg masses on the following scale: 0 = no galls or no 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).

Means for egg mass ratings were calculated and resistant selections were made based on a mean rating of less than or equal to three (30 egg masses). These resistant selections were further evaluated in a greenhouse experiment that was planted on 20 Dec. 1996 in a randomized complete-block design with seven replications. Germinated seedlings were inoculated with 3500 eggs 10 d after planting. Egg-masses and root-gall ratings were measured on 25 and 26 March, as described above. Roots from four replications were blotted dry and weighed, and eggs were collected with NaOCl (Hussey and Barker, 1973) and counted.

Data were subjected to analysis of variance and genotypic means were compared by Fisher's protected least significant difference (LSD). Unless otherwise stated, all differences referred to in the text were significant at P 0.05.

For each country of origin represented by at least one nematode resistant core accession, the expected number of resistant accessions was calculated. Expected values were calculated by multiplying the number of accessions in the core collection from each country of origin by the percentage of resistant accessions in the core collection. Chi-square analysis was used to test for significant deviations from expected.

	Results and discussion

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 
These studies resulted in the identification of 56 accessions from the core collection that had an egg mass rating of 2.5 or less (Table 1) . Eggs were not counted for 13 of these accessions. The number of eggs per root system for five accessions was not different from Florunner, although four of these had fewer eggs per gram of root than the susceptible cultivar. Thirty-six core accessions showed a significant reduction in galling, egg-mass rating, egg count per root system, and egg count per gram of root in comparison with the susceptible cultivar Florunner.

Extremely high levels of resistance to M. arenaria are available in related Arachis spp. (Baltensperger et al., 1986; Nelson et al., 1989; Holbrook and Noe, 1990). Starr et al. (1995) observed high levels of resistance (<97% reduction of eggs per gram of roots compared with the susceptible recurrent parent) in F₂ individuals from the second, third, and fourth backcross generations derived from the resistant parent TxAG-7 (Simpson et al., 1993). None of the A. hypogaea accessions identified in our studies showed a level of resistance as high as the highest levels observed in wild species or interspecific material derived from these species. Twenty-one accessions from the core collection showed a 70% reduction in eggs per root system and in eggs per gram of root in comparison with Florunner (Table 1). Two of these accessions (PI 269064 and PI 295747) showed a 90% reduction in these variables compared with Florunner.

Theoretically, the reaction of a core accession should serve as an indicator for the cluster in the entire germplasm collection from which the accession was selected. The frequency of additional resistant accessions should be higher in clusters with resistant indicator values. Resistant indicators from screening the core collection identified 39 clusters in the entire germplasm collection that should be examined more thoroughly (Table 2) . Screening material from these clusters would require examining 871 accessions.

The only striking geographical pattern observed were relatively large numbers of resistant accessions from China and Japan (Table 3) . Eleven of the resistant accessions identified were from China. This was 20% of the resistant accessions, whereas <4% of the germplasm collection originated from China. Seven percent of the resistant accessions were from Japan, although <2% of the germplasm collection originated from Japan.

	ACKNOWLEDGMENTS

Received for publication July 29, 1999.

	REFERENCES

TOP ABSTRACT INTRODUCTION Materials and methods Results and discussion REFERENCES

 

• Baltensperger D.D., Prine G.M., Dunn R.A. Root-knot nematode resistance in Arachis glabrata. Peanut Sci. 1986;13:78-80.
• Brown A.H.D. The case for core collections. In: Brown A.H.D., et al. , ed. The use of plant genetic resources. Cambridge, UK: Cambridge Univ. Press, 1989:136-156.
• Daykin M.E., Hussey R.S. Staining and histopathological techniques in nematology. In: Barker K.R., et al. , ed. An advanced treatise on Meloidogyne. Vol. II: Methodology. Raleigh: North Carolina State Univ, 1985:39-48.
• 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.
• 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., 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 Meloidogyne arenaria in Arachis spp. and the implications on development of resistant peanut cultivars. Peanut Sci. 1990;17:35-38.
• 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., Anderson W.F. Identification and evaluation of additional sources of resistance to peanut root-knot nematode in Arachis hypogaea L. Peanut Sci. 1996;23:91-94.
• 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.
• Nelson S.C., Simpson C.E., Starr J.L. Resistance to Meloidogyne arenaria in Arachis spp. germplasm. Suppl. J. Nematol. 1989;21:654-660.
• Simpson C.E., Nelson S.C., Starr J.L., Woodard K.E., Smith O.D. Registration of TxAG-6 and TxAG-7 peanut germplasm lines. Crop Sci. 1993;33:1418.[Free Full Text]
• Starr J.L., Simpson C.E., Lee T.A., Jr. Resistance to Meloidogyne arenaria in advanced generation breeding lines of peanut. Peanut Sci. 1995;22:59-61.
• Taylor A.L., Sasser J.N. Biology, identification and control of root-knot nematodes (Meloidogyne Species). Raleigh: North Carolina State Univ, 1978.

This article has been cited by other articles:

				S. L. Dwivedi, N. Puppala, H. D. Upadhyaya, N. Manivannan, and S. Singh Developing a Core Collection of Peanut Specific to Valencia Market Type Crop Sci., March 19, 2008; 48(2): 625 - 632. [Abstract] [Full Text] [PDF]

				Y. Chu, L. Ramos, C. C. Holbrook, and P. Ozias-Akins Frequency of a Loss-of-Function Mutation in Oleoyl-PC Desaturase (ahFAD2A) in the Mini-Core of the U.S. Peanut Germplasm Collection Crop Sci., November 7, 2007; 47(6): 2372 - 2378. [Abstract] [Full Text] [PDF]

				K. R. Kottapalli, M. D. Burow, G. Burow, J. Burke, and N. Puppala Molecular Characterization of the U.S. Peanut Mini Core Collection Using Microsatellite Markers Crop Sci., July 30, 2007; 47(4): 1718 - 1727. [Abstract] [Full Text] [PDF]

				C. C. Holbrook and W. Dong Development and Evaluation of a Mini Core Collection for the U.S. Peanut Germplasm Collection Crop Sci., June 24, 2005; 45(4): 1540 - 1544. [Abstract] [Full Text] [PDF]

				H. D. Upadhyaya Variability for Drought Resistance Related Traits in the Mini Core Collection of Peanut Crop Sci., May 27, 2005; 45(4): 1432 - 1440. [Abstract] [Full Text] [PDF]

				C. C. Holbrook, P. Timper, and A. K. Culbreath Resistance to Tomato spotted wilt virus and Root-Knot Nematode in Peanut Interspecific Breeding Lines Crop Sci., May 1, 2003; 43(3): 1109 - 1113. [Abstract] [Full Text] [PDF]

				H. D. Upadhyaya, P. J. Bramel, R. Ortiz, and S. Singh Developing a Mini Core of Peanut for Utilization of Genetic Resources Crop Sci., November 1, 2002; 42(6): 2150 - 2156. [Abstract] [Full Text] [PDF]

				C.C. Holbrook, P. Timper, and H.Q. Xue Evaluation of the Core Collection Approach for Identifying Resistance to Meloidogyne arenaria in Peanut Crop Sci., July 1, 2000; 40(4): 1172 - 1175. [Abstract] [Full Text]

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 (11) Citing Articles via Google Scholar Google Scholar Articles by Holbrook, C.C. Articles by Johnson, A.W. Search for Related Content PubMed Articles by Holbrook, C.C. Articles by Johnson, A.W. Agricola Articles by Holbrook, C.C. Articles by Johnson, A.W.