Increase in grain protein percentage in high-yielding common wheat breeding lines by genes from wild tetraploid wheat

Summary Forty-one breeding lines of common wheat, derived from crosses between the Israeli cultivars Miriam and Lakhish and high-protein lines of wild tetraploid wheat, Triticum turgidum var. dicoccoides, were tested for various protein and yield parameters in field trials, under typical agronomic conditions. All lines had a higher grain protein percentage (GPP) than the leading Israeli cultivar Deganit, which was grown as a control. Grain yield (GY) ranged in the breeding lines from a low of 2.44 t/ha to as high as that of Deganit (6.95 t/ha). Despite the weak negative correlation between GPP and GY, several lines excelled both in GPP and in GY. The grain protein yield (GPY) of some of these selected breeding lines was higher than that of Deganit; e.g., 1.19 t/ha in the best line vs. 1.02 t/ha in Deganit. The 16.7% increase in GPY in this line reflected a more efficient utilization of nitrogen.     

Causes of negative correlations between grain yield and grain protein concentration in common wheat

Summary In a study designed to investigate the nature and basis of the relationships between grain yield (GY) and grain protein concentration (GBC) in common wheat, 11 populations, including 4 homozygous-homogeneous and 7 heterozygous-heterogeneous populations, were evaluated in a space planted and a solid seeded trial. Analysis of yield and protein data from each population revealed that phenotypic and environmental correlations between GY and GPC were negative and highly significant, whereas genetic correlation was significant in only one of 7 segregating populations studied. These results suggested that the inverse relationships between GY and GPC, although phenotypically real, were not caused by genetic factors. It would appear that environmental factors, source-sink interactions, and dilution of protein by non-protein compounds were the major agents that caused undesirable associations between the two traits.Contribution No. of the Department of Plant Science, University of Alberta, Edmonton, Alberta, Canada T6G2P5     

The use of grain protein deviation for identifying wheat cultivars with high grain protein concentration and yield

The relationship between grain protein concentration and grain yield in different cultivars of winter wheat was examined in a series of field experiments carried out over three years, in which 13, 12 and 8 cultivars were studied in each year, respectively. The plants were grown at sites located in Shropshire, west-central England, in years 1 and 2, and at three other locations in eastern England in year 3. Above ground plant samples were collected at an thesis and again at maturity, when they were separated into grain and straw, and analysed for dry matter and N content. Analysis of residuals from regression of grain protein concentration on grain yield (grain protein deviation, GPD) showed that some cultivars had a higher grain protein concentration than was predicted from grain yield alone. It was deduced that the capacity to accumulate a higher grain protein concentration than predicted from grain yield is under genetic control and thus may be improved through breeding. Other factors (weight of N accumulated in the biomass at anthesis, weight of N accumulated in the biomass between anthesis and maturity and the concentration of N remaining in the straw at maturity) were added step-wise into the regression to enable statistical analysis of their relative contributions to grain protein. High GPD may be achieved through increased N accumulation after anthesis, combined with efficient re-translocation of vegetative N reserves. The use of GPD provides a selection criteria in wheat breeding programs to screen for increased grain protein concentration without a concurrent grain yield reduction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic analysis of hexaploid wheat,Triticum aestivum using intervarietal chromosome substitution lines—protein content and grain weight

Summary The 21 intervarietal chromosome substitution lines of the cultivar Hope in Chinese Spring were used to analyse the genetic differences between the two cultivars Hope and Chinese Spring in grain protein content and grain weight.Only one chromosome of Hope, 5D, significantly influenced grain protein content of Chinese Spring. Its influence was of only minor effect and was to decrease protein content expression of Chinese Spring. It has been postulated that the genetic control of protein content, in this instance, is most likely due to many genes each of small effect.Five chromosomes of Hope influenced the 1000 grain weight value of normal Chinese Spring, all increasing its expression. Chromosomes 1A, 4A and 5B were of major effect and 3A and 6A of comparatively minor effect. A minimal estimate of five genes determines the difference in grain size between these cultivars. The possible evolutionary significance of the contribution of the A genome of bread wheat to grain size determination is discussed. On the basis of certain findings of this study, proposals are made for breeding for increased grain size in hexaploid wheat.     

Relationship between common wheat (Triticum aestivum L.) gluten proteins and dough rheological properties

This paper reports the correlation between the rheological properties of bread wheat dough and the types and quantities of endosperm proteins in 28 common wheat cultivars. Different methods were used to analyse the allelic composition of these cultivars and the relative quantities of the different proteins contributing to the gluten structure. Neither dough strength (W) nor tenacity/extensibility (P/L) correlated with allelic composition. Different wheats with the same allelic composition (i.e., with respect to glutenins) showed different rheological properties. The glutenins were the most influential components of W and P/L, especially the high molecular weight (HMW) glutenin subunits and in particular the type x form. These proteins seem to increase W and are the main constituents of the gluten network. The gliadins and low molecular weight (LMW) glutenin subunits appear to act as a “solvent”, and thus modify the rheological properties of the dough by either interfering with the polymerisation of the HMW glutenin subunits, or by altering the relative amounts of the different types of glutenin available. Thus, the protein subunits coded for by the alleles Glu-B1x7 and Glu-D1x5 stabilised the gluten network, whereas those coded for by Glu-B1x17 and Glu-D1x2 had the opposite effect. Dough properties therefore appear to depend on the glutenin/gliadins balance, and on the ratio of the type x and type y HMW proteins. The influence of external factors seems to depend on the allelic composition of each cultivar.     

Vegetative protein and its relation to grain protein in high and low grain protein winter wheats

Summary Better understanding of the physiological and genetic basis of wheat grain protein will contribute to breeding efforts for this characteristic. This study provides information about plant protein distribution in high and low grain protein winter wheats (Triticum aestivum L.) at different growth stages and its relation to grain protein. Field experiments involved two winter wheats with high grain protein, Redwin and Lancota, and two with low grain protein, Centurk and Brule in two years. Protein content in the head, the upper three leaves, the first and second leaf, and the peduncle were estimated with Near Infrared Reflectance Spectrophotometer (NIR) at five growth stages. High protein cultivars had higher leaf protein at ripe and higher protein content in the heads at most growth stages than low grain protein cultivars. High protein cultivars had lower protein content in the peduncle than low protein cultivars at ripe. Correlation coefficients between plant-part protein and grain protein ranged from 0.48 to 0.87 for the heads, from –0.45 to –0.79 for the peduncle, and from 0.55 to 0.84 for the leaves. A combination of head, peduncle, and first leaf protein at heading was significantly related to grain protein (R²=0.71). Indirect selection for head, peduncle, and first leaf (flag leaf) protein at heading should result in increased grain protein. Recurrent selection for increased grain protein, with parent selectionbefore anthesis and hybridization should be successful.     

Increased grain protein content and its association with agronomic and end-use quality in two hard red spring wheat populations derived from Triticum turgidum L. var. dicoccoides

Suitability of wheat (Triticum aestivum L.) for many food products depends on its unique protein. Elevated grain protein content (GPC) and its quality influences the bread making properties of wheat. The objective of this study was to examine the association of elevated GPC with agronomic and end-use quality in two hard red spring wheat recombinant inbred (RI) populations derived from wild emmer (Triticum turgidum L. var. dicoccoides). The two hard red spring populations (ND683/Bergen and Glupro/Bergen) were developed using a single-seed-descent method. ND683 and ‘Glupro’ are high in GPC (180 g kg^-1), presumably due to the introgression of gene(s) from Triticum turgidum L. var. dicoccoides and ‘Bergen’ is low in GPC (145 g kg^-1). From each of the two populations 12 high- and 12 low-GPC RI lines (F_5:7) were selected for replicated testing at two North Dakota (ND) locations in 1995. In both populations, the high-GPC lines had significantly (p < 0.05) higher values compared to the low-GPC lines for mean GPC and water absorption. Mean grain yield of the high-GPC lines was not significantly different from the low-GPC lines in both populations. In the ND683/Bergen population, the high-GPC lines had significantly (p < 0.05) higher values than the low-GPC lines for mean plant height, days to heading, and flour extraction. GPC was significantly (p < 0.05)and negatively associated with test weight and also significantly (p < 0.01) and positively associated with water absorption in the Glupro/Bergen population. In these populations, results suggested that it may be possible to select lines that combine higher GPC and acceptable yield level, but later in maturity and taller in plant height. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationship among planted and harvested kernel weights and grain yield and protein percentage in winter wheat

Summary Wheat (Triticum aestivum L.) kernel weight is an important yield component and seed quality factor that appears to be declining with recent cultivar releases in the major U.S. wheat region. The objectives of experiments were to detmrmine the relationship between planted and harvested 1000-kernel weights and their effect on grain yield and grain protein percentage. Twelve popular hard red winter wheat cultivars were grown with recommended practices at 10 Kansas locations for three years. Rank correlation coefficients between kernel weights and grain yields and protein percentages were calculated.Correlations of planted and harvested kernel weights over all cultivars with grain yield were inconsistent, being positive for some locations and years and negative for other locations and years. Planted kernel weights and grain yields of individual cultivars were not related, but harvested kernel weights and grain yields were correlated positively for eight of the 12 cultivars. Harvested kernel weights and grain protein percentages frequently were correlated positively at individual locations, but always were correlated negatively for individual cumtivars. It was concluded that high stable harvested wheat kernel weight is important as a component of grain yield under a range of environments and that improving this trait would benefit all segments of the wheat industry.Contribution No. 84-395-J, Department of Agronomy, Kansas State University, Manhattan, Kansas 66506 USA.     

Flag leaf area in five spring wheat crosses and the relationship to grain yield

Summary Five spring wheat crosses were evaluated over a 6-year period using comparisons between F₂ and F₃ data and between near-isogenic F₄ populations selected for flag leaf area. Nonsignificant r values for F₂ vs. F₃ flag leaf measurements may be due to the effect of environment on flag leaf area, but are probably also an indication of low heritability for this plant character. Near-isogenic populations selected on the basis of flag leaf area showed little difference in grain yield, an indication that other plant parts must be more influential in determining grain yield. Flag leaf area, by itself, appears not to be a good index to plant performance.Joint contribution of ARS/USDA and the Montana Agricultural Experiment Station. Published with approval of the Director of the Montana Agricultural Experiment Station as Paper No. 725. Journal Series. Use of data from Research Centers at Moccasin. Havre. Huntley, and Kalispell is gratefully acknowledged.     

Chromosomal location of genes controlling grain size in a large grained selection of wheat (Triticum aestivum L.)

Summary Grain size in wheat is the most stable yield component and has a favorable effect on flour yield. To identify the chromosomes associated with the large grains of line G603-86, (grain weight over 60 mg and grain length of about 9 mm), F₃ lines, extracted from F₂ populations obtained from F₁ monosomics of crosses between G603-86 (P₁) and the monosomic set of Favorit (P₂) were tested in the field. ANOVA showed significant differences among parents for grain weight and grain length, but not for grain width or the factor expressing the difference in grain form and density. Homoeologous groups had significant effects on grain weight and on all components of grain weight, while genomes were not significantly different for any of these characters. Grain weight was significantly increased by chromosomes 6D and 4A of G603-86. Grain length was significantly increased by chromosomes 4A, 4B, 2B, 3A and 1B, grain width by chromosomes 1A and 1B, and the factor form-density by chromosomes 6D and 6A. The high grain size in G603-86 results from the effects of genes located on many chromosomes which affect grain dimensions, form and density.     

The high-molecular-weight glutenin subunit composition of Soviet wheat varieties

Summary One hundred and twenty-eight wheat varieties bred in the Soviet Union were screened for the composition of high-molecular-weight (HMW) subunits of glutenin. In general, variability was low compared to that seen in varieties from other countries. However, varieties from different regions showed distinctive patterns, in some cases clearly due to the use of particular parents in certain breeding programmes, but in others possibly due to the adaptive value of particular alleles to the environmental conditions under which the varieties were bred. For example, among spring varieties, the Glu-D1 allele encoding subunits 2+12 was more common in varieties from areas with limited rainfall than was the allele encoding subunits 5+10.The pattern of HMW glutenin subunits amongst varieties with superior bread-making quality showed few differences from that amongst bread-making varieties of lower quality.Abbreviations BMQ bread-making quality - HMW high-molecular-weight - LMW low-molecular-weight - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Russian wheat aphid-induced protein alterations in spring wheat

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a perennial, serious pest of wheat (Triticum aestivum L.) in the western United States. Current methodologies used to enhance RWA resistance in wheat germplasm could benefit from an understanding of the biochemical mechanisms underlying resistance to RWA. This study was initiated to identify specific polypeptides induced by RWA feeding that may be associated with RWA resistance. The effects of RWA feeding on PI 140207 (a RWA-resistant spring wheat) and Pavon (a RWA-susceptible spring wheat) were examined by visualizing, silver-stained denatured leaf proteins separated by two-dimensional polyacrylamide gel electrophoresis. Comparisons of protein profiles of noninfested and RWA-infested Pavon and PI 140207 revealed a 24-kilodalton-protein complex selectively inhibited in Pavon that persisted in PI 140207during RWA attack. No other significant qualitative or quantitative differences were detected in RWA-induced alterations of protein profiles. These results suggest that RWA feeding selectively inhibit synthesis and accumulation of proteins necessary for normal metabolic functions in susceptible plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Limited but specific variations of seed storage proteins in Japanese common wheat (Triticum aestivum L.)

The electrophoretic banding patterns ofgliadin in common wheat lines derived fromJapan were determined byacid-polyacrylamide gel electrophoresis. For the 107 wheat lines used in our study,27 different patterns were identified, 13corresponding to the -gliadin, 8 tothe , -gliadin and 6 to the-gliadin. The gliadin patterns ofJapanese wheat cultivars and landracesgreatly differed from the patterns of wheatlines from other countries, and thevariation seen in wheat lines from Japanwas limited to 46 patterns. Sevencollection or breeding areas in Japanshowed different frequencies in theirgliadin patterns. Combining the gliadinpatterns with high molecular weightglutenin subunit compositions, 67combinations were observed. One gliadinpattern consisting of -gliadinpattern F, , -gliadinpattern H and -gliadin pattern Dwas frequently found in many Japanese wheatlines, though the other patterns werelimited to only one or two wheat lines.     

Deficiency of individual high molecular weight glutenin subunits affords flexibility in breeding strategies for bread-making quality in wheat Triticum aestivum L.

High-molecular-weight (HMW) glutenin subunits in wheat Triticumaestivum L., allelic variation for which affects bread-making quality, areencoded by Glu-1 homoeoloci located on the homoeologous group1 chromosomes. Many alleles at Glu-B1 and Glu-D1 producetwo subunits, an x-type of low electrophoretic mobility in polyacrylamidegels, and a y-type of high mobility. In the current study, a combination ofnear isogenic lines of cultivar `Sicco' has been used to characterise theeffect upon quality of the absence of individual subunits 7 (Glu-B1x-type), 12 (Glu-D1 y-type) and, assuming an additive model ofsubunit action, 2 (Glu-D1 x-type). Absence of subunit 7 gave amoderate reduction in SDS-sedimentation volume, indicating its associationwith lower gluten strength (confirmed by Farinogram and Extensogramstudies), yet, from a full mixing input bake, a moderate increase in loafvolume and a considerable improvement in loaf score (an overall evaluationof loaf quality). Absence of subunit 12 gave a slightly larger reduction inSDS-volume, yet no change in loaf volume or score. Absence of bothsubunits 2+12 gave a larger reduction again in SDS-volume, a moderatereduction in loaf volume and a large reduction in loaf score. Absence ofsubunit 2 alone is therefore predicted to reduce SDS-volume, loaf volumeand score such that loss of this x-type subunit would lead to larger changesin quality parameters than loss of y-type subunit 12. A general conclusionof the study is that, while deficiency for HMW glutenin subunits generallyleads to reduced gluten strength and viscoelasticity, the resultantintermediate gluten strength may on occasions lead to improvements in loafperformance in situations where the base gluten strength is high. Theremay, then, be contexts in breeding programmes where selection fordeficiency would be a possible strategy for improving bread-making quality,adding to the flexibility available to the breeder. Somewhat unexpectedly,additional analysis found that, in the genetic background of cultivar `Sicco'used in this study, subunits 7+8 at Glu-B1 were indistinguishablefrom their allelic counterparts subunits 7+9 for virtually all characters, andthat subunits 2+12 at Glu-D1, while inferior in performance formixing properties compared to subunits 5+10, were associated with goodloaf characteristics.     

Response to selection for grain yield and harvest index in F2, F3 and F4 derived lines of two wheat crosses

Summary Aspects of selection for yield and harvest index were investigated by simulating selection using data from random pedigreed F₂, F₃, F₄ and F₅ derived lines from two crosses grown in plots at two sites over two years.Improvement in yield through selection was obtained when the response was measured at the same site and in the same year as the selection. Selecting the best 10 per cent of F₂ to F₄ derived lines gave F₅ derived lines that outyielded random selections by 19 to 53 per cent for one cross and 5 to 23 per cent for the second cross. These lines were 41 to 50 per cent better than the mid-parent in one cross, but were less than the mid-parent in the other cross.However, the response to selection when measured in a different year was little better than random selection. The effect of different sites also reduced the effectiveness of selection.Selection of harvest index in early generations for improvement of yield was ineffective when response was measured at the same site in the same year, or in different years.Contrary to some theoretical proposals, the same improvement in yield was obtained by selecting in early or late generations. While high yielding genotypes may be lost by delaying selection, this is counteracted by the better predictive value of late generations due to their greater homozygosity and homogeneity.     

The relation between wheat lines derived from the F2, F3, F4 and F5 generations for grain yield and harvest index

Summary The relationships between the F2, F3, F4 and F5 generations for grain yield were determined using random, pedigreed lines derived from each generation. The lines from two crosses were grown in plots at two sites over two years. In the first year, only F2 and F3 derived lines were available, but in the second year the F2 to F5 were grown.Correlations between lines in one generation and the mean of lines derived from them in a following generation increased as the generations were advanced. Correlations between consecutive generations were higher than those between generations two or three apart. Correlations between F2 and F5 derived lines, which indicate the effectiveness of selecting F2 lines, varied from 0.10 ns to o.49^** when lines from both generations were grown in the same environment. Correlations between years of lines from the same or different generations were low and often non-significant.Harvest index was measured on the F2 and F3 derived lines at the one site in the first year. Selection for improvement of grain yield using harvest index was no more effective than selection for yield directly, when considered across years.It is conclued that, while gains in yield can be achieved by selecting for yield in early generations, a foremost consideration needs to be the influence of different sites and years on the effectiveness of selection.     

Mass selection of wheat for grain filling without transient photosynthesis

Summary Post-anthesis chemical desiccation of wheat (Triticum aestivum L.) plants in the field eliminates transtent photosynthesis by killing all green tissues, thus revealing the plant's capacity for grain filling from stored stem reserves, as the case is for post-anthesis stress such as drought or leaf diseases. This study was conducted to investigate whether mass selection for large kernels under chemical desiccation would lead to the improve ment of grain filling in the absence of transient photosynthesis.Six crosses of common spring wheat were subjected to three cycles of mass selection from F₂ through F₁ when selection was performed for large kernels by sieving grains from plants that were erther chemically desiccated after anthesis, or not (controls). The resulting 36 bulks (six crosses by three selection cycles by two selection environments) were compared with their respective F₂ base populations, when tested with and without chemical desiccation.Selection for large kernels under potential conditions (without chemical desiccation) did not improve kernel weight under potnetial conditions, evidently because these materials were lacking in genetic variation for kernel weight under potential conditions. In four of the crosses, 3rd cycle selection for large kernels under potential conditions decreased kernel weight under chemical desiccation. On the other hand, selection for large kernels under chemical desiccation was effective in improving kernel weight and test weight under chemical desiccation, depending on the cross and the selection cycle, with no genetic shift in mean days to heading or mean plant height. Selection for large kernels under chemical desiccation was also effective in some cases in increasing kernel weight under potential conditions. The results are interpreted to show that selection under potential conditions and under chemical desiccation operate on two different sources for grain filling, namely transient photosynthesis and stem reserve utilization, respectively. In order to expose genetic variability for stem reserve utilization to selection pressure, transient photosynthesis must be eliminated, as done by chemical desiccation in this study.     

Development of hard white winter wheats for a hard red winter wheat region

Summary Hard white winter wheat (HWWW) occupies a very limited area of the USA, but its purported advantages suggest that its production in the major hard red winter wheat (HRWW) region may be feasible. Objectives of our investigations were to develop experimental HWWW lines that combined desirable attributes-grain yield, functional grain quality, and resistance to preharvest sprouting-in single genotypes for comparison with popular cultivars in the major US RHWW region. Forty-four lines from seven parental combinations were tested in randomized complete block designs at three Kansas locations during the 1981–82 and 1982–83 seasons. Agronomic traits, grain yield, grain quality, and preharvest sprouting were measured. Plant characteristics and grain yield were similar in the HWWW experimental lines and the HRWW check cultivar, Newton. Mean grain SDS-sedimentation value and grain protein content of most experimental lines equaled or exceeded that of the check. Dough mixing times frequently were shorter for the experimental lines than for the check cultivar, whereas loaf volumes were greater. Falling number usually was similar in all geneotypes, but -amylase was higher in field-harvested grain of white lines than the check; both measures were more favorable than grain trade standards. We concluded that production of high yielding, high quality hard white winter wheat genotypes is feasible in the US breakbasket.Contribution no. 84-349-J, Department of Agronomy, Kansas State University, Manhattan, KS 66506 USA.     

Location of genes for high grain protein percentage and other quantitative traits in wild wheat Triticum turgidum var. dicoccoides

Summary The genetic control of grain protein percentage (GPP) in the wild tetraploid wheat, Triticum turgidum var. dicoccoides, was determined by crossing four accessions of this taxonomic variety with durum cultivar Inbar, and analyzing the parents, F₁ and F₂ populations. Reciprocal crosses indicated no cytoplasmic effect on GPP. The F₂ variation was continuous in all crosses, showing no transgressive segregation. However, crosses between different accessions of var. dicoccoides showed transgressive segregation indicating the presence of different genes for high GPP in these accessions. Grain protein percentage was mostly codominant with high GPP, showing either no dominance, or a weak dominance. Heritability coefficients (broad sense) ranged from 0.30 to 0.53. Correlation coefficients between GPP and yield components were usually significantly negative, with the exception of the number of spikelets per spike, and in some crosses, grain weight.The number and chromosomal location of genes coding for high GPP were determined by the association between GPP and 27 markers (23 morphological and 4 biochemical markers). For this purpose, the genetic control of these markers, their linkage groups and chromosomal location were studied. At least four loci for high GPP that segregated in the F₂ populations are suggested: one on chromosome arm 1AS, marked by the black glume gene (Bg); one on 1BS, marked by the HMW gliadin locus Gli-B1; one on group 5, marked by the genes for beaked glume (Bkg) and toothed palea (Tp); and one on group 7, marked by the kinky neck gene (Kn). The relationship between GPP and several yield components was studied in a similar manner. In general, loci of markers that correlated positively with high GPP were not correlated with a decrease in yield components. Moreover, several loci of var. dicoccoides were associated with an increase in yield components.The utilization of markers for chromosomal location of genes coding for quantitative traits is compared to the technique of aneuploid analysis, commonly used in wheat. The significance of the above findings for breeding is discussed.     

Patterns of RFLP-based genetic diversity in germplasm pools of common wheat with different geographical or breeding program origins

A set of 292 accessions of common wheat (Triticum aestivum L.) representing 21 germplasm pools based on geographical or breeding program origins was assayed for RFLP diversity. Thirty cDNA and genomic DNA probes and the HindIII restriction enzyme were employed for RFLP analysis. About 61% of all 233 scored bands were present in 75% or more of the accessions. All but one of the 30 probes revealed polymorphism, and the average number of distinct patterns per probe over all accessions was 9.5.Polymorphic Information Content (PIC) values within a pool varied from 0 to 0.9 and depended on the identities of both the germplasm pool and the probe. Rare banding patterns with a relative frequency of ≤0.2 within a pool were detected. These rare patterns were more likely to occur in pools exhibiting high levels of heterogeneity. The highest level of polymorphism was observed in the Turkish landraces from Southwest Asia. The Eastern U.S. soft red winter wheat germplasm pool was more genetically diverse than the other advanced germplasm pools, and nearly as diverse as the Turkish landrace pool. RFLP-based genetic relationships between germplasm pools generally tracked expectations based on common geographical origin, breeding history and/or shared parentages. The Chinese wheat landraces from Sichuan, Tibet, and Yunnan provinces were distinct from other pools. Similarity matrices for among-pool genetic distance estimates based on either band frequencies or banding pattern frequencies showed good correlation with matrices derived from Nei and Li's mean genetic similarity estimates (r=−0.82^** and r=−0.73^**, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.