Genetic region responsible for the differences of starch properties in two glutinous rice cultivars in Hokkaido,Japan

Starch properties are major determinants of grain quality and food characteristics in rice (Oryza sativa L.). Control of starch properties will lead to the development of rice cultivars with desirable characteristics. We performed quantitative trait locus analysis and detected a putative region on chromosome 2 associated with phenotypic variation of starch properties in two glutinous rice varieties developed in the Hokkaido region of Japan: ‘Kitayukimochi’, which has a low pasting temperature and creates soft rice cakes, and ‘Shirokumamochi’, which has a high pasting temperature and creates hard rice cakes. Starch branching enzyme IIb (SbeIIb) was identified as a candidate gene within the region. Sequence analysis of SbeIIb in parental lines identified two single-nucleotide polymorphisms (SNPs) with non-synonymous mutations in the coding region of the ‘Shirokumamochi’ genotype (SbeIIb^sr). We genotyped over 100 rice cultivars, including 28 rice varieties in the Honshu region of Japan, using the CAPS marker, which was designed using one of the SNPs. However, SbeIIb^sr was not found in rice cultivars in Honshu. Distribution analysis indicated that SbeIIb^sr was introduced to the rice breeding population in Hokkaido from the American variety ‘Cody’ via the Hokkaido cultivar ‘Kitaake’. As a result, SbeIIb^sr was distributed only in progenies of ‘Kitaake’.     

Construction of a linkage map based on retrotransposon insertion polymorphisms in sweetpotato via high-throughput sequencing

Sweetpotato (Ipomoea batatas L.) is an outcrossing hexaploid species with a large number of chromosomes (2n = 6x = 90). Although sweetpotato is one of the world’s most important crops, genetic analysis of the species has been hindered by its genetic complexity combined with the lack of a whole genome sequence. In the present study, we constructed a genetic linkage map based on retrotransposon insertion polymorphisms using a mapping population derived from a cross between ‘Purple Sweet Lord’ (PSL) and ‘90IDN-47’ cultivars. High-throughput sequencing and subsequent data analyses identified many Rtsp-1 retrotransposon insertion sites, and their allele dosages (simplex, duplex, triplex, or double-simplex) were determined based on segregation ratios in the mapping population. Using a pseudo-testcross strategy, 43 and 47 linkage groups were generated for PSL and 90IDN-47, respectively. Interestingly, most of these insertions (~90%) were present in a simplex manner, indicating their utility for linkage map construction in polyploid species. Additionally, our approach led to savings of time and labor for genotyping. Although the number of markers herein was insufficient for map-based cloning, our trial analysis exhibited the utility of retrotransposon-based markers for linkage map construction in sweetpotato.     

Distribution of photoperiod-insensitive allele Ppd-A1a and its effect on heading time in Japanese wheat cultivars

The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9–9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that ‘Purple Straw’ and ‘Tohoku 118’ were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.     

生长秀节对糯玉米淀粉晶体结构和糊化特性的影响

以8个糯玉米品种为材料,利用X-射线衍射仪(X-Ray)和快速黏度分析仪(RVA)分析了淀粉在春季和秋季的晶体结构和糊化特性。结果表明,生长季节不影响淀粉的结晶类型,供试糯玉米淀粉样品的X-射线衍射图谱均表现出典型的“A”型衍射特征。然而,淀粉的晶体结构和糊化特性在生长季节间存在显著差异。和春季糯玉米淀粉相比,秋季糯玉米淀粉具有较高的结晶度、尖峰强度、峰值黏度、谷值黏度、终值黏度和崩解值。糯玉米淀粉的回复值较低,且秋季糯玉米淀粉显著低于春季糯玉米淀粉。淀粉的结晶度、尖峰强度和糊化特征值存在显著的基因型差异。相关分析表明,结晶度和各尖峰强度呈两两显著正相关。结晶度和峰值黏度、崩解值极显著正相关(相关系数分别为0.72和0.85),和谷值黏度、糊化温度显著正相关(相关系数分别为0.52和0.55),和回复值显著负相关(相关系数-0.49)。糯玉米淀粉糊化特性在不同生长季节中的变化主要由淀粉晶体结构(结晶度和尖峰强度)变化所致。     

淀粉型甘薯品种直链淀粉含量、糊化特性和乙醇发酵特性的关系

以15个淀粉型甘薯品种为试验材料,测定其直链淀粉含量、糊化特性和乙醇发酵特性,并分析它们之间的差异和相互关系。结果表明,不同甘薯品种的干物率、淀粉含量和直链淀粉含量(AC)均存在较大差异,相关分析表明,AC与干物率、淀粉含量之间呈极显著正相关;不同品种甘薯的糊化特性之间存在一定差异,但RVA谱特征值之间关系密切;不同甘薯品种的乙醇发酵特性之间也存在较大差异,乙醇含量与发酵强度之间呈极显著正相关。进一步分析表明,AC与RVA各特征值之间相关性不显著,而干物率、淀粉含量与糊化温度(PT)均呈极显著正相关(相关系数分别为r=0.661, P<0.01; r=0.670, P<0.01);AC与乙醇含量、发酵强度之间有显著正相关关系(相关系数分别为r=0.653, P<0.01; r=0.698, P<0.01),但与发酵效率、发酵黏度的相关性不显著;发酵黏度与崩解值(BDV)呈显著负相关(r= –0.563, P<0.05),与消减值(SBV)显著正相关(r=0.639, P<0.05),而乙醇含量、发酵效率和发酵强度与淀粉RVA各特征值之间的相关性均不显著。聚类分析将15个品种分为3大类,第I类品种AC和BDV均较高,第II类品种的AC最高、BDV最低,而第III类品种AC最低、BDV最高。甘薯的AC和BDV可以作为评价甘薯乙醇发酵特性的指标,同时较高AC和BDV值应是燃料乙醇专用甘薯品种的选育方向。     

基因型、地点及其互作对内蒙古小麦主要品质性状的影响

选用来自我国春播麦区高、中、低3种筋力类型的9个品种, 于2003和2004年分别种植在内蒙古6个代表性地点, 研究了不同品种在年份和地点间籽粒硬度、蛋白质含量、和面仪参数和淀粉糊化特性等主要品质性状的变化规律。结果表明, 所测品质性状受基因型和地点效应的影响均达极显著水平, 除籽粒蛋白质含量外, 其他品质性状受基因型和地点互作效应的影响达显著或极显著水平。强筋类品种的蛋白质含量、灰分含量、沉降值、和面时间、耐揉性和峰值黏度均较高, 出粉率和稀澥值中等。中筋类品种出粉率、和面时间和耐揉性较高, 灰分含量、峰值黏度和稀澥值较低。弱筋类品种的灰分含量、峰值黏度和稀澥值较高, 籽粒硬度、蛋白质含量、出粉率、沉降值、和面时间、耐揉性低。所有品种品质性状在地点间存在较大差异, 乌海市灰分含量、和面时间和耐揉性高, 籽粒硬度、沉降值、峰值黏度和稀澥值较低。杭锦后旗出粉率高, 蛋白含量和沉降值较低, 其他性状表现中等。呼和浩特市籽粒硬度、蛋白含量、面粉灰分、沉降值、和面时间和耐揉性高, 出粉率、峰值黏度和稀澥值低。赤峰市多数性状表现中等。通辽市籽粒硬度、蛋白质含量、峰值黏度、稀澥值和耐揉性较高, 其他性状表现中等。额尔古纳市蛋白含量和沉降值较高, 和面时间和耐揉性低。初步认为强筋和中筋类品种较适于种植在呼和浩特市与乌海市, 不适于种植在额尔古纳市; 2个弱筋类品种在6个地点均不太适宜种植。     

Development of PCR-based DNA marker for detection of white carrot contamination caused by Y2 locus

In carrot (Daucus carota L.), the taproot colors orange, yellow and white are determined mostly by the Y, Y2, and Or loci. One of the most severe issues in carrot seed production is contamination by wild white carrot. To evaluate the contamination ratio, easily detectable DNA markers for white carrot are desired. To develop PCR-based DNA markers for the Y2 locus, we have re-sequenced two orange-colored carrot cultivars at our company (Fujii Seed, Japan), as well as six white- and one light-orange-colored carrots that contaminated our seed products. Within the candidate region previously reported for the Y2 locus, only one DNA marker, Y2_7, clearly distinguished white carrots from orange ones in the re-sequenced samples. The Y2_7 marker was further examined in 12 of the most popular hybrid orange cultivars in Japan, as well as ‘Nantes’ and ‘Chantenay Red Cored 2’. The Y2_7 marker showed that all of the orange cultivars examined had the orange allele except for ‘Beta-441’. False white was detected in the orange-colored ‘Beta-441’. The Y2_7 marker detected white root carrot contamination in an old open-pollinated Japanese cultivar, ‘Nakamura Senkou Futo’. This marker would be a useful tool in a carrot seed quality control for some cultivars.     

小麦籽粒淀粉与面粉的理化特性差异

面制食品的品质与籽粒淀粉理化特性关系密切, 糯质和非糯质小麦籽粒淀粉组分有明显差别。本研究比较了糯小麦(宁糯麦1号、扬糯麦1号)和非糯小麦(扬麦16、中国春)的淀粉与面粉的黏度特性、热力学特性、膨胀势、溶解度等参数, 旨在阐明小麦籽粒淀粉与面粉的理化特性差异。4个品种籽粒淀粉粒均以C型淀粉粒(粒径<2 μm)为主, 占96.14%~97.36%, 糯小麦C型淀粉粒的比例高于非糯小麦。籽粒淀粉中破损淀粉含量低于面粉中破损淀粉含量; 籽粒淀粉的膨胀势、透光度、热焓值和回生度高于面粉, 溶解度和淀粉糊化的起始温度、峰值温度、最终温度低于面粉。与非糯小麦相比, 糯小麦面粉具有较低的破损淀粉含量、黏度参数特征值和淀粉回生度, 较高的溶解度、膨胀势、透光率和热焓值。外源添加剂试验结果表明, 面粉中α-淀粉酶活性、蛋白质与脂肪含量以及食品加工过程中添加的蔗糖和氯化钠均影响面粉的糊化特性, 是造成淀粉与面粉理化特性差异的主要原因。     

Distribution of photoperiod-insensitive alleles Ppd-B1a and Ppd-D1a and their effect on heading time in Japanese wheat cultivars

The genotypes of photoperiod response genes Ppd-B1 and Ppd-D1 in Japanese wheat cultivars were determined by a PCR-based method, and heading times were compared among genotypes. Most of the Japanese wheat cultivars, except those from the Hokkaido region, carried the photoperiod-insensitive allele Ppd-D1a, and heading was accelerated 10.3 days compared with the Ppd-D1b genotype. Early cultivars with Ppd-D1a may have been selected to avoid damage from preharvest rain. In the Hokkaido region, Ppd-D1a frequency was lower and heading date was late regardless of Ppd-D1 genotype, suggesting another genetic mechanism for late heading in Hokkaido cultivars. In this study, only 11 cultivars proved to carry Ppd-B1a, and all of them carried another photoperiod-insensitive allele, Ppd-D1a. The Ppd-B1a/Ppd-D1a genotype headed 6.7 days earlier than the Ppd-B1b/Ppd-D1a genotype, indicating a significant effect of Ppd-B1a in the genetic background with Ppd-D1a. Early-maturity breeding in Japan is believed to be accelerated by the introduction of the Ppd-B1a allele into medium-heading cultivars carrying Ppd-D1a. Pedigree analysis showed that Ppd-B1a in three extra-early commercial cultivars was inherited from ‘Shiroboro 21’ by early-heading Chugoku lines bred at the Chugoku Agriculture Experimental Station.     

Low temperature induced changes in activity and protein levels of the enzymes associated to conversion of starch to sucrose in banana fruit

Storage at low temperature is the most frequently used method to extend the shelf life of banana fruit, and is fundamental for extended storage and transport over long distances. However, storage and transport conditions must be carefully controlled because of the high susceptibility of many commercial cultivars to chilling injury. The physiological behavior of bananas at low temperatures has been studied to identify possible mechanisms of resistance to chilling injury. The aim of this work was to evaluate differences in the starch-to-sucrose metabolism of a less tolerant and susceptible (Musa acuminata, AAA cv. Nanicão) and a more tolerant (M. acuminata × Musa balbusiana, AAB, cv. Prata) banana cultivar to chilling injury. Fruits of these cultivars were stored in chambers at 13 °C for 15 d, at which point they were transferred to 19 °C, where they were left until complete ripening. The low temperature induced significant changes in the metabolism of starch and sucrose in comparison to fruit ripened only at 19 °C. The sucrose accumulation was slightly higher in cv. Prata, and different patterns of starch degradation, sucrose synthesis, activity and protein levels of the α- and β-amylases, starch phosphorylase, sucrose synthase and sucrose phosphate synthase were detected between the cultivars. Our results suggest that starch-to-sucrose metabolism is likely part of the mechanism for cold acclimation in banana fruit, and the cultivar-dependent differences contribute to their ability to tolerate cold temperatures.     

播期对小麦面粉粉质参数及糊化特性的影响

于2002—2003年度采用4个不同基因型小麦品种豫麦18号、豫麦49号、百泉41和郑引1号,研究了播期对面粉粉质参数及淀粉糊化特性的影响。结果表明,小麦基因型和播期对品质性状均有一定的影响,但基因型效应明显大于播期效应。面粉弱化度、糊化温度及糊化时间随播期推迟呈现递增趋势,而湿面筋含量、峰值粘度和反弹值随播期的推迟呈递减趋势;播期对某些品质性状的影响因基因型不同而存在差异,这与其适宜播期不同有关。在试验条件下品质性状间的相关分析结果表明,淀粉峰值粘度、低谷粘度、最终粘度和膨胀势间的相关性达到显著或极显著水平。     

Expression of seed storage proteins responsible for maintaining kernel traits and wheat flour quality in common wheat under heat stress conditions

Heat stress during grain filling has been documented to decrease wheat grain yield and quality in arid regions worldwide. We studied the effect of heat stress on wheat flour quality in heat tolerant cultivars to define the effects of heat stress on flour quality and to identify germplasm combining traits for heat tolerance and good flour quality. We studied the kernel phenotypic traits, the expression of seed storage proteins (SSPs), and the resulting flour quality under heat and normal conditions. Under heat stress, all cultivars yielded narrow-shaped seeds, and increased protein contents as compared to the control plants grown under normal conditions. The specific sedimentation values used to estimate the gluten quality varied between cultivars. We identified cultivars that could maintain good flour quality under heat stress conditions: ‘Imam’, which possessed the Glu-D1d allele responsible for the suitable bread-making; ‘Bohaine’, which displayed high expression level of SSPs; and ‘Condor’, which possessed slight variations in the ratio of each SSP under heat stress conditions. Combining the desirable traits from these cultivars could yield a wheat cultivar with heat tolerance and good flour quality.     

QTL analysis for brown spot resistance in American rice cultivar ‘Dawn’

Rice brown spot (BS), caused by Bipolaris oryzae, causes yield loss and deterioration of grain quality. Using single-nucleotide polymorphism (SNP) markers, we conducted quantitative trait locus (QTL) analysis of BS resistance in backcross inbred lines (BILs) from a cross between an American rice cultivar, ‘Dawn’ (resistant), and ‘Koshihikari’ (susceptible). Four QTLs for BS resistance were detected in a three-year field evaluation, and ‘Dawn’ contributed the resistance alleles at all QTLs. The QTL with the greatest effect, qBSR6-kd, explained 15.1% to 20.3% of the total phenotypic variation. Although disease score and days to heading (DTH) were negatively correlated in all three years, qBSR6-kd was located near a QTL for DTH at which the ‘Dawn’ allele promoted heading. Another BS resistance QTL (qBSR3.1-kd) was unlinked to the QTLs for DTH. Therefore, these two QTLs are likely to be useful for breeding BS-resistant varieties without delaying heading. The other two BS resistance QTLs (qBSR3.2-kd and qBSR7-kd) were located near DTH QTLs at which the ‘Dawn’ alleles delayed heading. The QTLs reported here will be good candidates for developing BS-resistant cultivars.     

鲜食期和成熟期糯玉米粉理化特性的差异

以5个糯玉米品种为材料,研究其鲜食期和成熟期籽粒的理化特性。结果表明,糯玉米粉的最大吸收波长鲜食期和成熟期无显著差异,均表现出典型的糯性特征,禾盛糯1512成熟期的蓝值高于鲜食期,其余品种鲜食期和成熟期无显著差异。成熟期糯玉米粉具有较高的淀粉含量和较低的蛋白质含量。成熟期糯玉米粉的结晶度和膨胀势高于鲜食期,而溶解度和透光率低于鲜食期,但不同品种对收获期的响应不一致。中糯319鲜食期的黏度特性较优,其他4个品种成熟期较优,鲜食期收获的粤彩糯1号不能糊化。差示扫描量热仪结果表明,成熟期收获的糯玉米粉具有较低的转变温度(起始温度、峰值温度、终值温度)、热焓值、峰值指数以及较宽的糊化范围,鲜食期收获的糯玉米粉具有较低的回生值。相关分析表明,最大吸收波长与峰值黏度显著正相关(相关系数为0.63,P<0.05),与糊化温度显著负相关(相关系数为-0.86,P<0.01)。结晶度与糊化温度显著负相关(相关系数为-0.70,P<0.05),与热焓值、峰值指数及回生后的热焓值显著正相关(相关系数分别为0.74,P<0.01;0.62,P<0.05;0.74,P<0.01)。回生值与蓝值、最大吸收波长、结晶度及回生后的热焓值显著正相关(相关系数分别为0.64,P<0.05;0.61,P<0.05;0.69,P<0.05;0.96,P<0.01)。中糯319鲜食期收获具有较高的淀粉含量、结晶度和黏度特征值,适宜作鲜食;粤彩糯1号两个时期的回生值远低于其他品种,适宜制作低回生的食品。     

Mapping and use of QTLs controlling pod dehiscence in soybean

While the cultivated soybean, Glycine max (L.) Merr., is more recalcitrant to pod dehiscence (shattering-resistant) than wild soybean, Glycine soja Sieb. & Zucc., there is also significant genetic variation in shattering resistance among cultivated soybean cultivars. To reveal the genetic basis and develop DNA markers for pod dehiscence, several research groups have conducted quantitative trait locus (QTL) analysis using segregated populations derived from crosses between G. max accessions or between a G. max and G. soja accession. In the populations of G. max, a major QTL was repeatedly identified near SSR marker Sat_366 on linkage group J (chromosome 16). Minor QTLs were also detected in several studies, although less commonality was found for the magnitudes of effect and location. In G. max × G. soja populations, only QTLs with a relatively small effect were detected. The major QTL found in G. max was further fine-mapped, leading to the development of specific markers for the shattering resistance allele at this locus. The markers were used in a breeding program, resulting in the production of near-isogenic lines with shattering resistance and genetic backgrounds of Japanese elite cultivars. The markers and lines developed will hopefully contribute to the rapid production of a variety of shattering-resistant soybean cultivars.     

Variation in quality traits in common wheat as related to Chinese fresh white noodle quality

The variation in grain compositional traits related to Chinese fresh white noodle (CFWN) quality was examined in 25 leading Chinese common wheat cultivars and advanced lines. Large variations were observed in flour yield, flour particle size, protein and ash contents, farinograph and rapid visco-analyzer (RVA) parameters, flour colour components, and polyphenol oxydase (PPO) activity. An improved sensory method was proposed for adequately evaluating CFWN quality of common wheat flour based on methodology used in the Japanese quality scoring system for white salted noodles, but with major modifications in the score weight given to each noodle quality parameter. Large differences in CFWN quality were observed among Chinese wheat cultivars. The correlation coefficients (r) between starch paste breakdown (RVA) and noodle viscoelasticity and smoothness were 0.63 and 0.59, respectively, suggesting that in breeding wheat for high CFWN quality, the starch pasting properties are of major importance. Low ash content was significantly correlated (r = – 0.66) with bright white noodle colour.     

Detection and verification of QTLs associated with heat-induced quality decline of rice (Oryza sativa L.) using recombinant inbred lines and near-isogenic lines

Decline in the apparent quality of rice (Oryza sativa L.) grain due to high temperatures during ripening recently became a major concern in many areas in Japan. The occurrence of white-back kernels (WBK) is one of the main problems of heat-induced quality decline. We identified QTLs associated with the occurrence of WBK using recombinant inbred lines (RILs) and verified their effects using near-isogenic lines (NILs). The QTL analysis used F₇ and F₈ RILs derived from ‘Hana-echizen’ (HE), which is tolerant to high temperature, × ‘Niigata-wase’ (NW), which is sensitive to high temperature. Four QTLs were identified on chromosomes 3, 4, 6, and 9 (qWB3, qWB4, qWB6 and qWB9). To verify the effects of qWB6 and qWB9, we developed two NILs in which qWB6 or both were introduced from HE into the NW background. The HE allele at qWB6 significantly decreased WBK under multiple environments. The combination of qWB6 and qWB9 in an F₂ population derived from a cross between a NIL and NW showed that the NW allele at qWB9 significantly decreased WBK if the qWB6 allele was HE. These results will be of value in marker-assisted selection for the breeding of rice with tolerance to heat-induced quality decline.     

Close linkage of a blast resistance gene,Pias(t), with a bacterial leaf blight resistance gene,Xa1-as(t), in a rice cultivar ‘Asominori’

It has long been known that a bacterial leaf blight-resistant line in rice obtained from a crossing using ‘Asominori’ as a resistant parent also has resistance to blast, but a blast resistance gene in ‘Asominori’ has not been investigated in detail. In the present study, a blast resistance gene in ‘Asominori’, tentatively named Pias(t), was revealed to be located within 162-kb region between DNA markers YX4-3 and NX4-1 on chromosome 4 and to be linked with an ‘Asominori’ allele of the bacterial leaf blight resistance gene Xa1, tentatively named Xa1-as(t). An ‘Asominori’ allele of Pias(t) was found to be dominant and difference of disease severity between lines having the ‘Asominori’ allele of Pias(t) and those without it was 1.2 in disease index from 0 to 10. Pias(t) was also closely linked with the Ph gene controlling phenol reaction, suggesting the possibility of successful selection of blast resistance using the phenol reaction. Since blast-resistant commercial cultivars have been developed using ‘Asominori’ as a parent, Pias(t) is considered to be a useful gene in rice breeding for blast resistance.     

Effects of allelic variations in starch synthesis-related genes on grain quality traits of Korean nonglutinous rice varieties under different temperature conditions

Influences of allelic variations in starch synthesis-related genes (SSRGs) on rice grain quality were examined. A total of 187 nonglutinous Korean rice varieties, consisting of 170 Japonica and 17 Tongil-type varieties, were grown in the field and in two greenhouse conditions. The percentages of head rice and chalky grains, amylose content, alkali digestion value, and rapid visco-analysis characteristics were evaluated in the three different environments. Among the 10 previously reported SSRG markers used in this study, seven were polymorphic, and four of those showed subspecies-specific allele distributions. Six out of the seven polymorphic SSRG markers were significantly associated with at least one grain quality trait (R² > 0.1) across the three different environments. However, the association level and significance were markedly lower when the analysis was repeated using only the 170 Japonica varieties. Similarly, the significant associations between SSRG allelic variations and changes in grain quality traits under increased temperature were largely attributable to the biased allele frequency between the two subpopulations. Our results suggest that within Korean Japonica varieties, these 10 major SSRG loci have been highly fixed during breeding history and variations in grain quality traits might be influenced by other genetic factors.     

不同小麦品种支链淀粉链长分配及其与淀粉理化特性的关系

以糯性与非糯性小麦品种（系）为材料,研究直、支链淀粉蓝值、支链淀粉链长分配及其与淀粉理化特性的关系。结果表明,直链淀粉的蓝值和最大吸收波长均显著大于支链淀粉;支链淀粉蓝值和最大吸收波长表现为中筋小麦＞弱筋小麦＞强筋小麦＞糯小麦,蓝值和最大吸收峰间呈极显著正相关,蓝值和吸收波长越大,说明支链淀粉含较长的支链。经Sephadex G75分离支链淀粉的支链,可得到3个组分,非糯小麦长B链(DP≥65.8)组分占支链淀粉百分含量最低,中等B链(29＜DP＜65.8)组分其次,短B链和A链(DP≤29)组分高达65%左右,前两个组分含量表现为弱筋小麦＞强筋小麦＞中筋小麦,且同一类型不同品种间也存在差异;而糯小麦未能洗脱出长B链。相关分析表明,除崩解值外,长B链与黏度各特征值均呈极显著正相关,与结晶度呈显著正相关,说明长B链含量显著影响淀粉的理化特性。