Physical Mapping of Puroindoline b-2 Genes in ... - PubAg - USDA

1 downloads 0 Views 597KB Size Report
(Chen et al., 2010a, 2011a, 2011b). Using the gametocidal chromosome of jointed goatgrass (Aegilops cylindrica Host),. Endo and Gill (1996) isolated 436 Del ...
RESEARCH

Physical Mapping of Puroindoline b-2 Genes in Wheat using ‘Chinese Spring’ Chromosome Group 7 Deletion Lines Hongwei Geng, Brian S. Beecher, Zhonghu He, and Craig F. Morris*

ABSTRACT The puroindoline genes (Puroindoline a-D1 and Puroindoline b-D1), located very near to the distal end of the short arm of chromosome 5D (distal to fraction arm length of 0.78) have a significant effect on grain hardness. Puroindoline b-2 (Pinb-2) is another puroindoline gene family that exists as a homoeologous series on group 7 chromosomes. However, a more detailed localization (physical mapping) of the Pinb-2 genes has not been conducted. In the present study, 24 group 7 long-arm chromosome deletion stocks of ‘Chinese Spring’ were used to physically map three Pinb-2 variant genes: Pinb-2v1, Pinb-2v2, and Pinb-2v4. All three genes were found to be physically located on the most distal 0.11 to 0.16 fraction arm length of chromosomes 7AL, 7BL, and 7DL in Chinese Spring. These results contribute insight into wheat (Triticum aestivum L.) genome synteny, structure, and organization and provide a useful metric for germplasm and population relationships. Future studies may further resolve the physical mapping of Pinb-2 genes at the ends of group 7 chromosomes and contribute to a better understanding of the molecular and genetic basis of kernel hardness.

H. Geng, Dep. of Crop & Soil Sciences, Washington State Univ., Pullman, WA 99164; affi liated with the Western Wheat Quality Lab., and College of Agronomy, Xinjiang Agricultural Univ., 42 Nanchang Rd., Uvumqi 830052, Xinjiang, China; B.S. Beecher and C.F. Morris, USDA-ARS Western Wheat Quality Lab., E-202 Food Science & Human Nutrition Facility East, Washington State Univ., Pullman, WA 99164-6394; Z. He, Institute of Crop Science, National Wheat Improvement Center/The National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguancun South St., Beijing 100081, China, and the International Maize and Wheat Improvement Center (CIMMYT) China Office, c/o CAAS, 12 Zhongguancun South St., Beijing 100081, China. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of other that may also be suitable. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. Received 17 Apr. 2012. *Corresponding author ([email protected]). Abbreviations: CS, Chinese Spring; Del, deletion; FL, fraction arm length; LDN, Langdon; PCR, polymerase chain reaction.

G

rain hardness plays an important role in end-use quality and usage and consequently is a major factor affecting trade of hexaploid (common) wheat (Law et al., 1978; Mattern et al., 1973). Wheat is normally classified into soft, mixed, or hard types on the basis of grain hardness (Morris, 2002). Giroux and Morris (1997, 1998) showed that grain hardness is controlled by two tightly linked major genes Puroindoline a (Pina) and Puroindoline b (Pinb) that are located on the short arm of chromosome 5D in common wheat. The deletion stocks of Endo and Gill (1996) in Chinese Spring Published in Crop Sci. 52:2674–2678 (2012). doi: 10.2135/cropsci2012.04.0241 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA 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.

2674

WWW.CROPS.ORG

CROP SCIENCE, VOL. 52, NOVEMBER– DECEMBER 2012

(CS) and a BC7–derivative in ‘Alpowa’ (Morris and Beecher 2012) facilitated the placement of Pina and Pinb in the most distal 0.22 fraction arm length (FL) of 5DS. Minor genes for grain hardness have been identified on chromosomes 1A, 2AL, 2DL, 5BL and 6DS (Law et al., 1978; Mattern et al., 1973; Perretant et al., 2000; Pomeranz and Williams, 1990; Sourdille et al., 1996). The Grain Softness Protein-1 (Gsp-1) gene is tightly linked to Pina and Pinb on chromosome 5DS (Chantret et al., 2005) and was the first puroindoline-like gene identified (Blochet et al., 1993; Morris, 2002). In contrast to the Pin genes, the Gsp-1 gene is retained as a homoeologous series with copies on the 5A, 5B, and 5D chromosomes in common wheat (Blochet et al., 1993; Chantret et al., 2005). To date, a correlative relationship between Gsp-1 genes and grain hardness has not been established (Gollan et al., 2007; Massa et al., 2004; Tranquilli et al., 2002), even though the GSP-1 protein shows approximately 40% identity and 60% similarity to PINA and PINB proteins, respectively (Chantret et al., 2005; Turner et al., 1999). Although a definitive function of GSP-1 proteins is still unknown, they may possibly play a role in plant defense (Gollan et al., 2007). Chantret et al. (2005) found evidence for ancient evolutionary duplications of puroindoline-like genes in wheat. Located at the 5DS Hardness locus were sequences termed Pinb-relic and PseudoPinb. No other information on these apparent vestigial genes has been forthcoming. Puroindoline b-2 genes were discovered by Wilkinson et al. (2008) by “mining” the dbEST (expressed sequence tag database) (http://www.ncbi.nlm.nih.gov/dbEST/) with Pinb sequence. Three unique sequences were identified and designated “Pin b variant 1,” “Pin b variant 2,” and “Pin b variant 3” (abbreviated PinBv1, PinBv2, and PinBv3, respectively). They subsequently isolated and sequenced complementary DNA clones that provided corresponding gene sequences. The deduced amino acid sequences of these genes, compared to Pinb-D1a, were 57, 57, and 60% identical (PinBv1, PinBv2, and PinBv3, respectively). Genetic mapping studies were interpreted as indicating that PinBv1, PinBv2, and PinBv3 were probably “encoded by the same Pinb-2 locus on 7A, termed Pinb-A2” (Wilkinson et al., 2008). In contrast, Chen et al. (2010a) physically mapped PinBv1, PinBv2, and PinBv3 to 7DL, 7BL, and 7B, respectively, using CS ditelosomics, nullisomic-tetrasomics, and disomic substitution lines. In addition, a fourth Pinb-2 variant was discovered (PinBv4), which mapped to 7AL. These results supported a homoeologous series model with PinBv2 and PinBv3 possibly allelic; PinBv3 was not present in CS. To simplify the nomenclature and more closely conform to the Catalogue of Gene Symbols for Wheat (McIntosh et al., 2009; Morris and Bhave, 2008), these genes were redesignated Pinb-2v1, Pinb-2v2, Pinb-2v3, and Pinb-2v4. Chen et al. (2011a, 2011b) corroborated the previous chromosome assignments and extended them by showing that Langdon durum [Triticum turgidum L. subsp. CROP SCIENCE, VOL. 52, NOVEMBER– DECEMBER 2012

durum (Desf.) Husn.] lacked Pinb-2v1. This gene, however, was present in Langdon (LDN) disomic substitutions of CS, LDN 7D(7A) and LDN 7D(7B), supporting its 7D location in CS. Pinb-2v2 was assigned to 7B in CS but was not found in LDN. Pinb-2v3 was again found to be absent in CS but was present in LDN. Pinb-2v4 was localized to 7A in CS and also in LDN. Previous results (Chen et al., 2010a, 2011a, 2011b) were consistent with Pinb-2v2 and Pinb-2v3 being allelic at the 7B locus. Variety surveys of Chen et al. (2010b), Geng et al. (2012), and Chen et al. (2012) were consistent with this model. In addition, two sequence polymorphic forms of Pinb-2v3 were recently observed in durum and hexaploid wheat varieties (Chen et al., 2012). The physical position of Puroindoline b-2 genes has not been resolved further than the whole chromosome or whole chromosome arm. In the present study, 24 group 7 long-arm chromosome deletion stocks of CS (Endo and Gill, 1996) were used to refine the physical map of the three known Pinb-2 variants in CS: Pinb-2v1, Pinb-2v2, and Pinb-2v4.

MATERIALS AND METHODS Deletion Lines Twenty-four group 7 wheat homozygous deletion (Del) lines in CS were used and included 10 Del lines of chromosome 7AL (CS Del7AL), seven Del lines of chromosome 7BL (CS Del7BL), and seven Del lines of chromosome 7DL (CS Del7DL). Seed of these genetic stocks was obtained from Prof. B.S. Gill (Kansas State University); plants were grown in the greenhouse at Washington State University, Pullman, WA. Wheat chromosome bin maps can be accessed at the Group-7 long-arm deletion lines in Chinese Spring wheat (http://www.k-state.edu/wgrc/Germplasm/ Deletions/grp7L.html [accessed 12 Apr. 2012]). The chromosome arm cytological FL value in a given Del line identifies the physical breakpoint in the deleted chromosome and the length of the remaining chromosome arm from the centromere relative to the total length of the euploid arm.

Physical Mapping of the Wheat Puroindoline b-2 Variants Genomic DNA was extracted from leaves of individual seedlings for each Del line about 3 wk after emergence, according to the procedures described by Sharp et al. (1989), and was analyzed for Puroindoline b-2 variants. To obtain physical mapping of Puroindoline b-2 variants in wheat, Pinb-2v1, Pinb-2v2, and Pinb-2v4 were identified using gene specific primers (Table 1). Amplification of Pinb-2v1, Pinb-2v2, and Pinb-2v4 was performed as described by Chen et al. (2010a, 2011a), with minor modifications. Polymerase chain reaction (PCR) reactions were performed in an MJ Research PTC-200 thermalcycler in a total volume of 25 μL including 250 μM of each deoxyribonucleotide triphosphate, 10 pmol of each primer, 100 ng of genomic DNA, 1x reaction buffer (50 mM KCl, 10 mM Tris-Cl, and 1.5 μM MgCl 2, pH 8.4), and 1 U Taq DNA polymerase (Promega). Polymerase chain reaction cycling conditions were 94°C for 5 min followed by 45 cycles of 94°C for 50 s, 63 to 68°C (for

WWW.CROPS.ORG

2675

Table 1. Polymerase chain reaction (PCR) primers used in generating Puroindoline b-2 variant gene sequences in Chinese Spring chromosome group 7 deletion lines, annealing temperatures, and expected fragment sizes. Gene Pinb-2v1 Pinb-2v2 Pinb-2v4

Forward primer

Reverse primer

PCR annealing temperature

Fragment size

GGTTCTCAAAACTGCCCAT CTTGTAGTGAGCACAACCTTTGCA CCTTTCTCTTGTAGTGAGCACAACCA

ACTTGCAGTTGGAATCCAG GTATGGACGAACTTGCAGCTGGAG GACGAACTTGCAGTTGGAATCCAA

63°C 65°C 68°C

319 bp 401 bp 403 bp

primer-specific annealing temperatures, see Table 1) for 50 s, and 72°C for 1 min with a fi nal extension of 72°C for 10 min. The PCR products were separated by electrophoresis on a 1.5% (w/v) agarose gels. The bands were stained with ethidium bromide and visualized using ultraviolet light.

RESULTS Physical Mapping of Puroindoline b-2 Variant 1 Pinb-2v1 was found to be present in all 17 CS Del lines for 7AL and 7BL but absent in the seven Del lines for the long arm of chromosome 7D (with break points at Del7DL-6, FL = 0.01; Del7DL-1, FL = 0.14; Del7DL-5, FL = 0.30; Del7DL-2, FL = 0.61; Del7DL-4, FL = 0.76; Del7DL-8, FL = 0.77; and Del7DL-7, FL = 0.84) (Table 2). This result indicates that Pinb-2v1 is located in the distal 0.16 FL portion of 7DL, between breakpoint FL 0.84 (Del7DL-7) and the undeleted (FL 1.00) chromosome of euploid CS (Fig. 1a).

Physical Mapping of Puroindoline b-2 Variant 2 The gene-specific primers for Pinb-2v2 amplified PCR fragments in all the CS Del lines for chromosomes 7AL and 7DL whereas no PCR fragment was amplified in the seven Del lines for the long arm of chromosome 7B (Del7BL-1, FL = 0.40; Del7BL-9, FL = 0.45; Del7BL-7, FL = 0.63; Del7BL-5, FL = 0.69; Del7BL-10, FL = 0.78; Del7BL-6, FL = 0.84; and Del7BL-3, FL = 0.86) (Table 2). This result indicates that the Pinb-2v2 gene is similarly located in the most distal portion (in this case FL 0.14), distal to the breakpoint in Del7BL-3 (Fig. 1b).

Physical Mapping of Puroindoline b-2 Variant 4 The gene-specific primers for Pinb-2v4 produced a PCR fragment in all of the 14 chromosome 7DL and 7BL Del lines (Table 2). However, no PCR fragment was produced in any of the 10 Del lines for 7AL (Del7AL-4, FL = 0.18; Del7AL-14, FL = 0.31; Del7AL-1, FL = 0.39; Del7AL-11, FL = 0.40; Del7AL-5, FL = 0.63; Del7AL-6, FL = 0.80; Del7AL-8, FL = 0.83; Del7AL-16, FL = 0.86; Del7AL-2, FL = 0.87; and Del7AL-9, FL = 0.89) (Table 2). This result similarly indicates that the Pinb-2v4 gene is located most distally on 7AL, beyond the FL 0.11 breakpoint in Del7AL-9 (Fig. 1c).

DISCUSSION Previous physical mapping studies using CS ditelosomic, nullisomic-tetrasomic, and CS-Wichita and CS-LDN disomic substitution lines indicated that Pinb-2v1, Pinb2v2, Pinb-2v3, and Pinb-2v4 loci were located somewhere 2676

Table 2. Chinese Spring (CS) chromosome group 7 deletion (Del) lines analyzed for Puroindoline b-2 variants, arm fraction length (FL), and presence (+) or absence (–) of a polymerase chain reaction (PCR) fragment†. Deletion line

FL values Pinb-2v1 Pinb-2v2 Pinb-2v4

CS euploid CS Del7AL-1 CS Del7AL-2 CS Del7AL-4 CS Del7AL-5 CS Del7AL-6

– 0.39 0.87 0.18 0.63 0.80

+ + + + + +

+ + + + + +

+ – – – – –

CS Del7AL-8 CS Del7AL-9 CS Del7AL-11 CS Del7AL-14 CS Del7AL-16 CS Del7BL-1 CS Del7BL-3 CS Del7BL-5 CS Del7BL-6 CS Del7BL-7 CS Del7BL-9 CS Del7BL-10 CS Del7DL-1 CS Del7DL-2 CS Del7DL-4 CS Del7DL-5 CS Del7DL-6 CS Del7DL-7 CS Del7DL-8

0.83 0.89 0.40 0.31 0.86 0.40 0.86 0.69 0.84 0.63 0.45 0.78 0.14 0.61 0.76 0.30 0.10 0.84 0.77

+ + + + + + + + + + + + – – – – – – –

+ + + + + – – – – – – – + + + + + + +

– – – – – + + + + + + + + + + + + + +



Gene-specific PCR primers for Puroindoline b-2 genes are listed in Table 1.

on chromosomes 7AL, 7BL, 7B and 7DL, respectively (Chen et al., 2010a, 2011a, 2011b). Using the gametocidal chromosome of jointed goatgrass (Aegilops cylindrica Host), Endo and Gill (1996) isolated 436 Del lines in CS. These Del lines are powerful tools for the refined physical mapping of wheat chromosomes and have been extensively used in physical mapping of the wheat genome (Delaney et al., 1995; Qi and Gill, 2001; Weng et al., 2000; Werner et al., 1992a, 1992b). To further localize the Puroindoline b-2 variants within each of the respective chromosome arms, 24 of these homozygous deletion stocks of CS for group 7 longarm chromosomes were characterized using gene-specific PCR primers for Pinb-2v1, Pinb-2v2, and Pinb-2v4. Our study confirms the previous physical mapping data on the existence of Pinb-2v1, Pinb-2v2, and Pinb-2v4 loci on the long arms of homoeologous group 7 chromosomes (Chen et al., 2010a, 2011a, 2011b) but also further shows that these Pinb-2 genes are located on the most distal

WWW.CROPS.ORG

CROP SCIENCE, VOL. 52, NOVEMBER– DECEMBER 2012

Figure 1. Physical map of the long arm of Chinese Spring chromosome 7D (leftmost). The identification of deletion line fraction arm length (FL) values of breakpoints is indicated on the right in parentheses. The chromosomal region (gray hatched bar) from FL = 0.84 to FL = 1.00 shows the putative location of the Pinb-2v1 gene. C-banding patterns of chromosomes are taken from Gill et al. (1991). Chromosome long arms point toward the bottom and the open arrow (left) indicates the position of the centromere. Physical map of the long arm of Chinese Spring chromosome 7B (center). The identification of deletion line FL values of breakpoints is indicated on the right in parentheses. The chromosomal region (gray hatched bar) from FL = 0.86 to FL = 1.00 shows the putative location of the Pinb-2v2 gene. C-banding patterns of chromosomes are taken from Gill et al. (1991). Chromosome long arms point toward the bottom and the open arrow (left) indicates the position of the centromere. Physical map of the long arm of Chinese Spring chromosome 7A (rightmost). The identification of deletion line FL values of breakpoints is indicated on the right in parentheses. The name of deletion lines values of breakpoints is indicated on the right. Numbers in parentheses indicate the FL values. The chromosomal region (gray hatched bar) from FL = 0.89 to FL = 1.00 shows the putative location of the Pinb-2v4 gene. Chromosome long arms point toward the bottom and the open arrow (left) indicates the position of the centromere.

portion of the chromosomes (Fig. 1). The “least” deleted chromosomes included in the study were Del7AL-9, Del7BL-3, and Del7DL-7 with FL ratios of 0.89, 0.86, and 0.84, respectively (Table 2). Within the limits of cytological resolution, it would appear that all homoeologous loci are at similar locations on the chromosome and likely follow a conserved synteny among the A, B, and D genomes. We may further point out that although the related puroindoline genes, Puroindoline a-D1 and Puroindoline b-D1, are also located very near to the distal end of their chromosome (distal to FL of 0.78), these genes are on a different homoeologous series (group 5) and on the short, as opposed to the long arm. In this study the location of Pinb-2v3 could not be physically mapped using this set of CS Del lines since Pinb-2v3 is not present in CS (Chen et al., 2010a, 2011a, 2011b). Using disomic substitution lines of Wichita in CS and CS in LDN durum, Pinb-2v3 was localized to 7B and 7BL (Chen et al., 2010a, 2011a, 2011b). In addition, past studies have suggested that Pinb-2v2 and Pinb-2v3 were likely allelic (Chen et al., 2010a, 2010b, 2011a, 2011b, 2012; Geng et al., 2012). Therefore, for now, we assume that both Pinb-2v2 and Pinb-2v3 reside on the distal end of the long arm of chromosome 7B. Future studies will need to more carefully address the allelic status of the two genes. In genetic mapping, Wilkinson et al. (2008) reported that three Puroindoline b-2 variants (PinBv1, PinBv2, and PinBv3) were probably located on the distal end of 7AL using three doubled haploid populations. In one of these populations derived from ‘Spark’ × ‘Rialto’, PinBv1 CROP SCIENCE, VOL. 52, NOVEMBER– DECEMBER 2012

was most tightly linked with Xwmc116 on the long arm of chromosome 7A. Xwmc116 was located at 82 cM and PinBv1 at 87 cM. Based on accumulating data, this result will need to be carefully reexamined. Acknowledgments The authors thank Prof. B.S. Gill and Jon Raupp of the Wheat Genetic and Genomic Resources Center, Manhattan, KS, for providing the deletion stock of Chinese Spring. Stacey Sykes assisted in the preparation of this manuscript.

References Blochet, J.E., C. Chevalier, E. Forest, E. Pebay-Peyroula, M.F. Gautier, P. Joudrier, M. Pézolet, and D. Marion. 1993. Complete amino acid sequence of puroindoline, a new basic and cystine-rich protein with a unique tryptophan-rich domain, isolated from wheat endosperm by Triton X-114 phase partitioning. Fed. Eur. Biochem. Soc. 329:336–340. doi:10.1016/0014-5793(93)80249-T Chantret, N., J. Salse, F. Sabot, S. Rahman, A. Bellec, B. Laubin, I. Dubois, C. Dossat, P. Sourdille, P. Joudrier, M.F. Gautier, L. Cattolico, M. Beckert, S. Ambourg, J. Weissenbach, M. Caboche, M. Bernard, P. Leroy, and B. Chaloub. 2005. Molecular basis of evolutionary events that shaped the Hardness locus in diploid and polyploid wheat species (Triticum and Aegilops). Plant Cell 17:1033–1045. doi:10.1105/tpc.104.029181 Chen, F., B.S. Beecher, and C.F. Morris. 2010a. Physical mapping and a new variant of Puroindoline b-2 genes in wheat. Theor. Appl. Genet. 120:745–751. doi:10.1007/s00122-009-1195-y Chen, F., X.L. Shang, C.F. Morris, F. Zhang, Z. Dong, and D. Cui. 2012. Molecular characterization and diversity of puroindoline b-2 variants in cultivated and wild diploid wheat. Genet. Resour. Crop Evol. (in press).

WWW.CROPS.ORG

2677

Chen, F., H.X. Xu, F.Y. Zhang, X.C. Xia, Z.H. He, D.W. Wang, Z.D. Dong, K.H. Zhan, X.Y. Cheng, and D.Q. Cui. 2011a. Physical mapping of puroindoline b-2 genes and molecular characterization of a novel variant in durum wheat (Triticum turgidum L.). Mol. Breed. 28:153–161. doi:10.1007/s11032-010-9469-2 Chen, F., F.Y. Zhang, X.Y. Cheng, C.F. Morris, H.X. Xu, Z.D. Dong, K.H. Zhan, and D.Q. Cui. 2010b. Association of Puroindoline b-B2 variants with grain traits, yield components and flag leaf size in bread wheat (Triticum aestivum L.) varieties of the Yellow and Huai Valleys of China. J. Cereal Sci. 52:247–253. doi:10.1016/j.jcs.2010.06.001 Chen, F., F.Y. Zhang, C.F. Morris, and D.Q. Cui. 2011b. A puroindoline multigene family exhibits sequence diversity in wheat and is associated with yield-related traits. In: F. Friedberg, editor, Gene duplication. InTech North America, Manhattan, NY. doi:10.5772/888. p. 279–288. Delaney, D.E., S. Nasuda, T.R. Endo, B.S. Gill, and S.H. Hulbert. 1995. Cytologically based physical maps of the group-3 chromosomes of wheat. Theor. Appl. Genet. 91:780–782. Endo, T.R., and B.S. Gill. 1996. The deletion stocks of common wheat. J. Hered. 87:295–307. doi:10.1093/oxfordjournals. jhered.a023003 Geng, H.W., B.S. Beecher, Z.H. He, A.M. Kiszonas, and C.F. Morris. 2012. Prevalence of Puroindoline D1 and Puroindoline b-2 variants in U.S. Pacific Northwest wheat breeding germplasm pools, and their association with kernel texture. Theor. Appl. Genet. 124:1259–1269. doi:10.1007/s00122-011-1784-4 Gill, B.S., B. Friebe, and T.R. Endo. 1991. Standard karyotype and nomenclature system for description of chromosome fragments and structural aberrations in wheat (Triticum aestivum). Genome 34:830–839. doi:10.1139/g91-128 Giroux, M.J., and C.F. Morris. 1997. A glycine to serine change in puroindoline b is associated with wheat grain hardness and low levels of starch-surface friabilin. Theor. Appl. Genet. 95:857–864. doi:10.1007/s001220050636 Giroux, M.J., and C.F. Morris. 1998. Wheat grain hardness results from highly conserved mutations in the friabilin components puroindoline a and b. Proc. Natl. Acad. Sci. USA 95:6262– 6266. doi:10.1073/pnas.95.11.6262 Gollan, P., K. Smith, and M. Bhave. 2007. Gsp-1 genes comprise a multigene family in wheat that exhibits a unique combination of sequence diversity yet conservation. J. Cereal Sci. 45:184– 198. doi:10.1016/j.jcs.2006.07.011 Law, C.N., C.F. Young, J.W.S. Brown, J.W. Snape, and A.J. Worland. 1978. The study of grain protein control in wheat using whole chromosome substitution lines. In: Seed protein improvement by nuclear techniques. International Atomic Energy Agency, Vienna, Austria. p. 483–502. Massa, A.N., C.F. Morris, and B.S. Gill. 2004. Sequence diversity of puroindoline-a, puroindoline-b, and the grain softness protein genes in Aegilops tauschii cross. Crop Sci. 44:1808– 1816. doi:10.2135/cropsci2004.1808 Mattern, P.J., R. Morris, J.W. Schmidt, and V.A. Johnson. 1973. Location of genes for kernel properties in the wheat variety ‘Cheyenne’ using chromosome substitution lines. In: E.R. Sears and L.M.S. Sears, editors, Proceedings of the 4th International Wheat Genetics Symposium, University of Missouri, Columbia, MO. 6–11 Aug. 1973. Agricultural Experiment Station, University of Missouri, Columbia, MO. p. 703–707. McIntosh, R.A., J. Dubcovsky, W.J. Rogers, C.F. Morris, R. Appels, and X.C. Xia. 2009. Catalogue of gene symbols for wheat: 2009 supplement. Annu. Wheat Newsl. 55:256–278.

2678

http://wheat.pw.usda.gov/ggpages/wgc/2009upd.htm l (accessed 12 Apr. 2012). Morris, C.F. 2002. Puroindolines: The molecular genetic basis of wheat grain hardness. Plant Mol. Biol. 48:633–647. doi:10.1023/A:1014837431178 Morris, C.F., and B.S. Beecher. 2012. The distal portion of the short arm of wheat (Triticum aestivum L.) chromosome 5D controls endosperm vitreosity and grain hardness. Theor. Appl. Genet. 125:247–254. Morris, C.F., and M. Bhave. 2008. Reconciliation of D-genome puroindoline allele designations with current DNA sequence data. J. Cereal Sci. 48:277–287. doi:10.1016/j.jcs.2007.09.012 Perretant, M.R., T. Cadalen, G. Charmet, P. Sourdille, P. Nicolas, C. Boeuf, M.H. Tixier, G. Branlard, S. Bernard, and M. Bernard. 2000. QTL analysis of bread-making quality in wheat using a doubled haploid population. Theor. Appl. Genet. 100:1167–1175. doi:10.1007/s001220051420 Pomeranz, Y., and P.C. Williams. 1990. Wheat hardness: Its genetic, structure and biochemical background, measurement and significance. In: Y. Pomeranz, editor, Advances in cereal science and technology Vol. X. AACC International, St. Paul, MN. p. 471–548. Qi, L.L., and B.S. Gill. 2001. High-density physical maps reveal that the dominant male-sterile gene Ms3 is located in a genomic region of low recombination in wheat and is not amenable to map-based cloning. Theor. Appl. Genet. 103:998–1006. doi:10.1007/s001220100699 Sharp, P.J., S. Chao, S. Desai, and M.D. Gale. 1989. The isolation, characterization and application in the Triticeae of a set of wheat RFLP probes identifying each homoeologous chromosome arm. Theor. Appl. Genet. 78:342–348. doi:10.1007/BF00265294 Sourdille, P., M.R. Perretant, G. Charmet, P. Leroy, M.F. Gautier, P. Joudrier, J.C. Nelson, M.E. Sorrels, and M. Bernard. 1996. Linkage between RFLP markers and genes affecting kernel hardness in wheat. Theor. Appl. Genet. 93:580–586. doi:10.1007/BF00417951 Tranquilli, G., J. Heaton, O. Chicaiza, and J. Dubcovsky. 2002. Substitutions and deletions of genes related to grain hardness in wheat and their effect on grain texture. Crop Sci. 42:1812– 1817. doi:10.2135/cropsci2002.1812 Turner, M., Y. Mukai, P. Leroy, B. Charef, R. Appels, and S. Rahman. 1999. The Ha locus of wheat: Identification of a polymorphic region for tracing grain hardness in crosses. Genome 42:1242–1250. Weng, Y., N.A. Tuleen, and G.E. Hart. 2000. Extended physical maps and a consensus physical map of the homoeologous group-6 chromosomes of wheat (Triticum aestivum L. em Thell.). Theor. Appl. Genet. 100:519–527. Werner, J.E., T.R. Endo, and B.S. Gill. 1992a. Toward a cytogenetically based physical map of the wheat genome. Proc. Natl. Acad. Sci. USA 89:11307–11311. doi:10.1073/ pnas.89.23.11307 Werner, J.E., R.S. Kota, B.S. Gill, and T.R. Endo. 1992b. Distribution of telomeric repeats and their role in the heating of broken chromosomes in wheat. Genome 35:844–848. doi:10.1139/g92-128 Wilkinson, M., Y.F. Wan, P. Tosi, M. Leverington, J. Snape, R.A.C. Mitchell, and P.R. Shewry. 2008. Identification and genetic mapping of variant forms of puroindoline b expressed in developing wheat grain. J. Cereal Sci. 48:722–728. doi:10.1016/j.jcs.2008.03.007

WWW.CROPS.ORG

CROP SCIENCE, VOL. 52, NOVEMBER– DECEMBER 2012