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a USDA-ARS, Western Integrated Cropping Systems Research Unit, 17053 N. Shafter Ave., Shafter, CA 93263
b USDA-ARS, SPARC, Crop Germplasm Research Unit, 2881 F&B Rd., College Station, TX 77845
c Dep. of Plant & Environmental Sciences, New Mexico State Univ., University Ave., Las Cruces, NM 88003
d Dep. of Plant Science, Univ. of California-Davis, Shafter Research and Extension Center, 17053 N. Shafter Ave., Shafter, CA 93263
e Univ. of California, Cooperative Extension, 4437B S. Laspina St., Tulare, CA 93274
f Dep. of Plant Pathology, Univ. of California-Davis, One Shields Ave., Davis, CA 95616
* Corresponding author (Mauricio.Ulloa{at}ars.usda.gov).
ABSTRACT
Four Pima cotton (Gossypium barbadense L.) germplasm lines, SJ-07P-FR01 (Reg. No. GP-910, PI 654065), SJ-07P-FR02 (Reg. No. GP-911, PI 654066), SJ-07P-FR03 (Reg. No. GP-912, PI 654067), and SJ-07P-FR04 (Reg. No. GP-913, PI 654068), were developed by the USDA–ARS and New Mexico State University Agricultural Experiment Station and jointly released with the University of California in 2008. The primary purpose for these releases is to provide germplasm with good levels of resistance to Fusarium wilt [Fusarium oxysporum f. sp. vasinfectum Atk. Sny & Hans] (FOV) race 4 to cotton breeders in California. Lines SJ-07P-FR01 to -FR03 originated from a cross made at New Mexico State University in 1997 of germplasm lines 8810 and NMSI 1601. The germplasm line SJ-07P-FR04 originated from reselection within the publicly released USDA–ARS germplasm line P 73. The lines were evaluated for resistance to race 4 in two field and three greenhouse trials conducted in 2003 and 2005. Five replicated field evaluations for yield potential, fiber characteristics, and other agronomic traits were conducted at Five Points, CA, Shafter, CA, and Maricopa, AZ, in 2005 and 2006. The SJ-07P-FR series possesses good resistance, moderate lint yield potential, and good to superior fiber length and strength. Caution should be applied when using these lines, and it should not be assumed that the lines provide complete resistance against FOV race 4.
Abbreviations: FOV, Fusarium oxysporum f. sp. vasinfectum • FR, Fusarium resistance • potato dextrose agar • MSD, minimum significant difference • RKN, Root-knot nematodes • SJV, San Joaquin Valley
Four Pima cotton (Gossypium barbadense L.) germplasm lines, SJ-07P-FR01 (Reg. No. GP-910, PI 654065), SJ-07P-FR02 (Reg. No. GP-911, PI 654066), SJ-07P-FR03 (Reg. No. GP-912, PI 654067), and SJ-07P-FR04 (Reg. No. GP-913, PI 654068), were developed by the USDA–ARS and New Mexico State University Agricultural Experiment Station and were jointly released with the University of California in 2008. The lines provide good levels of resistance to Fusarium wilt [Fusarium oxysporum f. sp. vasinfectum Atk. Sny & Hans] (FOV) race 4, while broadening the genetic base of race 4 resistant germplasm. These lines provide needed alternative sources of FOV resistance and broaden the genetic base of resistant germplasm critical to maintaining a healthy Pima cotton industry in the San Joaquin Valley of California. Before 2003, Fusarium wilt in California was thought to be primarily caused by FOV race 1, a soil-inhabiting organism that can survive for long periods in soils, even in the absence of cotton, making it nearly impossible to eradicate from a field. This race is typically found in sandy or sandy loam soils and produces the most severe yield impacts when present in combination with root-knot nematodes [Meloidogyne incognita Kofoid and White (Chitwood)] (Bell, 1984; Veech, 1984). Recently, University of California–Davis scientists (Kim et al., 2005) identified race 4 of FOV in California soils. This race, first identified in India on Asiatic cottons, had not previously been identified in the United States. In recent field investigations (Kim et al., 2005; Ulloa et al., 2006), race 4 FOV occurred in clay loam and loam soils, in which root knot nematode populations and root damage symptoms were absent. Disease symptoms caused by race 4 FOV have been most severe in susceptible Pima cultivars. However, this pathogen also commonly infects Acala and non-Acala Upland cottons. Because of the long-term survival potential of race 4 in field soils in the absence of cotton, host plant resistance has proven to be the most effective means of managing this disease. Before the release of SJ-07P-FR01, -FR02, -FR03, and -FR04, resistance to race 4 had been identified in a very restricted genetic base among commercial cultivars in California (Hutmacher et al., 2005; Ulloa et al., 2006). The primary purpose for releasing SJ-07P-FR01, -FR02, -FR03, and -FR04 is to provide germplasm with good levels of resistance to FOV race 4 and provide private and public breeders with sources of FOV resistance gene(s).
Methods
SJ-07P-FR01, SJ-07P-FR02, and SJ-07P-FR03 lines originated from a cross of germplasm lines 8810 and NMSI 1601. Line 8810 possesses superior fiber strength and high yield potential when grown in the high temperatures of the far western United States (Percy, 1998). Line 8810 was developed from a cross between P 73 x P 72. The P 73 parent of 8810 was developed from the cross P 53 x PS 6 (Percy and Turcotte, 1997). NMSI 1601 was developed by New Mexico State University Agricultural Experiment Station from a single plant selection within an open-pollinated synthetic population originating from Monseratt Sea Island, and it possesses excellent fiber length and fineness. SJ-07P-FR01 -FR02, and -FR03 germplasm lines originated from New Mexico State University at Las Cruces, NM, in 1997. Initial individual plant selection within the hybrid population was conducted in the F2 to F3 generations at Las Cruces, NM. A final series of individual plant selections was conducted in the F4 generation at Shafter, CA, from progeny rows. Subsequent generations for each line were advanced as individual progeny to obtain enough seed for replicated trials. SJ-07P-FR04 is a population originating from reselection within P 73. A series of individual plant selections was conducted on P 73 at the University of California West Side Research & Extension Center, Five Points, CA, and the Shafter Research & Extension Center, Shafter, CA. Two recurrent selections were applied for morphological uniformity such as plant height, leaf shape, petal spot, yield, and fiber properties. Phenotypically, the SJ-07-FR lines resemble typical Pima cottons with mid- to late maturity.
The lines were evaluated for resistance to FOV race 4 in two field trials conducted in 2003 and 2004 and in three greenhouse trials conducted in 2004 and 2005. Evaluations were performed on generations F5, F6, and F7 that were handled as populations. The lines were planted in fields known to be infested with FOV race 4. Plants in these fields consistently developed severe Fusarium symptoms (inoculum levels were unknown and varied from year to year). Lines were grown in one-row plots 5-m long with 1-m row spacing in a randomized complete block design with three replications in 2003 and 2004. For greenhouse evaluations, germplasm lines were seeded into a composite medium of vermiculite and peat moss before inoculation. Roots of 2- to 4-wk-old seedlings were gently washed to remove most of the soil medium. Then roots were dipped in water (nontreated plants as a control) or spore suspension of 1 x 105 conidia mL–1 of water for 2 min (treated plants). Inoculum for pathogenicity testing was obtained by placing a 25-mm2 piece of filter paper cultured with single spores on a potato dextrose agar (PDA) in 15-mL petri dishes for 2 wk. Spore suspensions were prepared by flooding colonized 2-wk-old cultures on PDA with water, scraping off the spores, and filtering the spore suspension through four layers of cheesecloth (Ulloa et al., 2006). After inoculation, plants were individually transplanted to pots filled with the composite medium. The experiment was a complete randomized design with five replications. Each replication was represented by 1 plant pot–1. The data presented in Table 1 were extracted from experiments with about 40 cultivars for greenhouse and about 80 cultivars for field. Cultivars were used as treatments for the statistical analyses. To determine the level of tolerance or resistance for each line, all plants were assayed at 4 to 6 wk after inoculation for foliar symptoms, vascular stain or brown color in the stem tissue, number of nodes, and plant height (from the node-cotyledons to the mainstem terminal) in centimeters. Individual plants from each line were rated for disease severity based on foliar symptoms and vascular stain. A 0 to 5 scale was used for foliar symptoms, where 0 = no foliar symptoms and 5 = plant death. A 0 to 5 scale was used for vascular stain, where 0 = no vascular staining and 5 = plant severely damaged and vascular staining evident throughout a cross-section of root tissue (up to node-cotyledons region).
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Characteristics
From two San Joaquin Valley (SJV) fields infested with FOV race 4 in 2003 and 2004, and three greenhouse evaluations in 2004 and 2005 at two different sites (the University of California–Davis and the Kearney Research and Extension Center, Parlier, CA), mean disease severity ratings of SJ-07P-FR01 ranged from 0.08 to 1.44 for foliar symptoms and 0.09 to 1.60 for vascular stain; SJ-07P-FR02 ranged from 0.33 to 1.56 for foliar symptoms and 0.41 to 1.22 for vascular stain; SJ-07P-FR03 ranged from 0.00 to 1.78 for foliar symptoms and 0.21 to 1.22 for vascular stain, and SJ-07P-FR04 ranged from 0.17 to 1.56 for foliar symptoms and 0.08 to 1.22 for vascular stain. The foliar symptoms of the susceptible parent NMSI 1601 ranged from 2.33 to 4.17, and for the two susceptible checks, ‘PS 7’ (Turcotte et al., 1992) and ‘DP744’ (U.S. PVP 20010004), foliar symptoms ranged from 2.33 to 4.58 and from 2.78 to 4.83, respectively (Table 1). The checks PS 7 and DP744 ranged from 2.22 to 4.42 and 2.44 to 4.67 for vascular stain, respectively. Symptoms of the most-resistant parent, 8810, ranged from 0.20 to 2.0 for foliar symptoms and 0.73 to 1.78 for vascular stain. Symptoms in the resistant check, ‘Phytogen 800’ (U.S. Patent 7332.657), ranged from 0.00 to 1.33 for foliar symptoms and 0.04 to 1.00 for vascular stain (Table 1).
Postemergence survival rates indicate that FOV race 4 was able to infect and kill cotton seedlings at high rates in the 6 wk following emergence. By the end of the field tests, an average of 25% of the emerged plant stand survived for susceptible checks (NMSI 1601, PS 7, and DP744), and 90% of the emerged plant stand survived for the resistant check, Phytogen 800. The various evaluations indicated survival rates of emerged plants at season's end ranging from 57% to 90% in the SJ-07P-FR series. In 2004, the percentage survival for the susceptible parent NMSI 1601 was 18%, survival for the two susceptible checks, PS 7 and DP744, was 6 and 2%, respectively, and survival for the resistant check was 84%. Survival of SJ-07P-FR01, -FR02, -FR03, and -FR04 was 76, 61, 63, and 57%, respectively.
A replicated trial in 2005 at Maricopa, AZ, revealed that fiber lengths and strengths of SJ-07P-FR01 (38.3 mm and 501.2 kN m kg–1), SJ-07P-FR02 (36.7 mm and 495.0 kN m kg–1), and SJ-07P-FR03 (37.3 mm and 477.2 kN m kg–1) were good to superior compared with the SJV Pima cotton standard, PS 7 (36.3 mm and 440.7 kN m kg–1) by the minimum significant difference (Waller–Duncan K-ratio t test, minimum significant difference [MSD] = 1.0 mm and 28.0 kN m kg–1) (Table 2 ). This trend continued at West Side, where fiber lengths and strengths of SJ-07P-FR01 (38.0 mm and 497.6 kN m kg–1), SJ-07P-FR02 (36.9 mm and 527.2 kN m kg–1), and SJ-07P-FR03 (36.5 mm and 475.3 kN m kg–1) were good to superior compared with the SJV Pima cotton standard, PS 7 (36.7 mm and 472.7 kN m kg–1) (MSD = 0.8 mm and 36.0 kN m kg–1). In 2005 at Maricopa, the more heat tolerant check cultivar, PS 7, produced significantly more lint yield (1309 kg ha–1) than the SJ-07P-FR populations (SJ-07P-FR01, -FR02, and -FR03) or the more heat sensitive check cultivar, Phytogen 800 (1112 kg ha–1). However, the yield of line SJ-07P-FR03 (1082 kg ha–1) did not differ from that of cultivar Phytogen 800. In 2005, cultivar Phytogen 800 produced a significantly higher yield (1800 kg ha–1) than the evaluated SJ-07P-FR populations and the PS 7 cultivar (1717 kg ha–1) at the West Side. At West Side the yield of line SJ-07P-FR03 (1591 kg ha–1) did not differ significantly from that of PS 7. Depending on location and entry, the SJ-07P-FR series produced yields that were from 3 to 30% lower than the check cultivars in 2005. In 2006, in a replicated trial at Shafter, CA, lint yields were not significantly different between SJ-07P-FR02, -FR03, -FR04, and the commercial check cultivars. However, the three SJ-07P-FR lines ranked numerically lower for yield and lint percentage compared with the checks. Variability in soil composition was possibly responsible for low yields in at least two of the four replicates for SJ-07P-FR02 and -FR03. Overall, the SJ-07P-FR series showed good fiber length and strength and low-to-average lint yields, lint percentage, and fiber elongation (Table 2).
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Availability
Small quantities of seed (10–25 g) are available to cotton breeders, geneticists, and other research personnel on written request to the corresponding author. It is requested that appropriate recognition of the source be given when these germplasm lines contributes to the development of a new breeding line, hybrid, or cultivar. Genetic material of these releases will be deposited in the National Plant Germplasm System, where they will be available for research purposes, including development and commercialization of new cultivars.
Acknowledgments
The authors would like to acknowledge Dr. Roy Cantrell (New Mexico State University) for providing the original (F2:3) seed from which SJ-07P-FR01 to FR03 originated. The assistance of University of California Cooperative Extension Farm Advisors (Dan Munk, Fresno County; Brian Marsh, Kern County; Ron Vargas, Madera and Merced counties), Bruce Roberts (California State University, Fresno), IPM Regional Advisor Peter Goodell (University of California Kearney Agricultural Center, Parlier), and Michael McGuire (WICSRU, Shafter) is gratefully acknowledged. Special thanks for field and greenhouse project support provided by Monica Biggs, Mark Keeley, Gerardo Banuelos, John Soares, Raul Delgado, Sarah Hutmacher, Anna Brown, Stan Bergen, Brian Neufeld, and James Frelichowski, from University of California County Cooperative Extension and Research and Extension Centers, and USDA-ARS, WICSRU. Access to field sites was possible with the permission and assistance of growers. Use of the greenhouse facilities of the University of California at the Kearney Research and Extension Center (Parlier, CA) and the assistance of Fred Swanson and Laura van der Staay of that center are gratefully acknowledged. Use of farm equipment and help of staff from the University of California Shafter Research and Extension Center are also gratefully acknowledged. We also thank the Cotton Foundation and the Supima Association for partial support of this study. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture, the University of California, or New Mexico State University.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication September 10, 2008.
References
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