淹水和干旱条件下水稻根系形成的QTLs及候选基因分析

为了研究不同水分条件下组成型根系性状和适应性根系性状的遗传机制,利用由IR64／Azucena发展的双单倍体（DH）群体分析了淹水和干旱条件下水稻幼苗种子根长（SRL）、不定根数（ARN）、总根干重（RW）及其对应的相对参数（干旱和淹水条件下根系性状的比值）的QTLs。淹水与干旱条件下检测到一个共同的种子根长QTL和一个共同的总根干重QTL。同时对前人发表的遗传群体定位的根系性状QTLs进行比较分析,检测到几个共同的根系性状QTLs。对与细胞伸长、分裂相关的候选基因进行了定位,其中4个细胞壁相关的ESTs（OsEXP2,OsEXP4,EXT和Xet）被定位在与不同水分条件下检测出的根系性状QTLs的相同区间。     

QTLs and epistasis for aluminum tolerance in rice (Oryza sativa L.) at different seedling stages

To investigate the genetic background for aluminum (Al) tolerance in rice, a recombinant inbred (RI) population, derived from a cross between an Al-sensitive lowland indica rice variety IR1552 and an Al-tolerant upland japonica rice variety Azucena, was used in culture solution. A molecular linkage map, together with 104 amplified fragment length polymorphism (AFLP) markers and 103 restriction fragment length polymorphism (RFLP) markers, was constructed to map quantitative trait loci (QTLs) and epistatic loci for Al tolerance based on the segregation for relative root length (RRL) in the population. RRL was measured after stress for 2 and 4 weeks at a concentration of 1mM of Al³⁺ and a control with a pH 4.0, respectively. Two QTLs were detected at both the 2nd and the 4th weeks on chromosomes 1 and 12 from unconditional mapping, while the QTL on chromosome 1 was only detected at the 2nd stress week from conditional mapping. The effect of the QTL on chromosome 12 was increased with an increase of the stress period from 2 to 4 weeks. The QTL on chromosome 1 was expressed only at the earlier stress, but its contribution to tolerance was prolonged during growth. At least one different QTL was detected at the different stress periods. Mean comparisons between marker genotypic classes indicated that the positive alleles at the QTLs were from the Al-tolerant upland rice Azucena. An important heterozygous non-allelic interaction on Al tolerance was found. The results indicated that tolerance in the younger seedlings was predominantly controlled by an additive effect, while an epistatic effect was more important to the tolerance in older seedlings; additionally the detected QTLs may be multiple allelic loci for Al tolerance and phosphorus-uptake efficiency, or for Al and Fe²⁺ tolerance. Received: 29 July 1999 / Accepted: 13 October 1999     

水稻糙米重金属Cd含量的QTL分析

镉(Cd²⁺)是一种分布较广泛、毒性较强的一种重金属, 文章利用韭菜青×IR26杂交衍生的一个重组自交系群体(Recombinant inbred lines, RIL)及构建的SSR分子遗传图谱, 对控制糙米中Cd²⁺含量的QTL进行分析, 为选育籽粒中Cd²⁺低吸收或低积累的水稻品种提供参考。结果表明, 在Cd²⁺胁迫(5 mg/kg)处理条件下, 共检测到2个与糙米Cd²⁺含量有关的QTLs, 分别位于水稻第11染色体上的标记RM6288-RM6544和RM167-RM5704之间, 其中qCCBR-11a对表型贡献率为11.17%, 加性效应0.089; qCCBR-11b对表型变异贡献率为7.66%, 加性效应0.075。相关分析显示, 糙米Cd²⁺含量与株高、每穗总粒数、每穗实粒数、结实率和千粒重等产量性状的相关性均不显著, 糙米中Cd²⁺含量是一个相对独立、由基因控制的遗传性状。     

QTLs and epistasis for seminal root length under a different water supply in rice (Oryza sativa L.)

To identify the genetic background of seminal root length under different water-supply conditions, a recombinant inbred (RI) population consisting of 150 lines, derived from a cross between an indica lowland rice, IR1552, and a tropical japonica upland rice, Azucena, was used in both solution culture (lowland condition) and paper culture (upland condition). Quantitative trait loci (QTLs) and epistatic loci for seminal root length were analyzed using 103 restriction fragment length polymorphism (RFLP) markers and 104 amplified fragment length polymorphism (AFLP) markers mapped on 12 chromosomes based on the RI population. One QTL for seminal root length in solution culture (SRLS) and one for seminal root length in paper culture (SRLP) were detected on chromosomes 8 and 1, and about 11% and 10% of total phenotypic variation were explained, respectively. The QTL for SRLP on chromosome 1 was very similar with the QTL for the longest nodal root referred to in a previous report; this QTL may be phenotypically selectable in a breeding program using paper culture. Five pairs of epistatic loci for SRLS were detected, but only one for SRLP, which accounted for about 60% and 20% of the total variation in SRLS and SRLP, respectively. The results indicate that epistasis is a major genetic basis for seminal root length, and there is a different genetic system responsible for seminal root growth under different water supply conditions. Received: 26 May 2000 / Accepted: 19 October 2000     

Mapping QTLs for seedling characteristics under different water supply conditions in rice (Oryza sativa)

A greater understanding of the genetics of responses to water deficit/drought may be helpful in improving water-deficit resistance in the early stages of growth in rice. A recombinant inbred population derived from a cross between Zhenshan 97 and Minghui 63 was grown in hydroponic culture to characterize the responses of seedlings to water deficit imposed by PEG 6000 and to identify quantitative trait loci (QTLs) for seedling characteristics under both well-watered and water-deficit conditions. Generally, the two parents showed significant differences in plant height (PH), maximum root length (MRL), shoot fresh weight (SFW), root fresh weight (RFW), number of roots and root:shoot ratio based on fresh weight under both well-watered and water-deficit conditions. For two parents, PH and SFW were significantly inhibited under water deficit. However, the other four traits had larger values under water deficit. Among 26 and 34 QTLs detected for the six traits studied under the well-watered and water-deficit conditions, respectively, a total of 14 QTLs for SFW, PH, RFW and MRL (23% of total QTLs detected) were detected in similar or tight linkage regions in both conditions. Among 11 intervals on 7 chromosomes identified to harbor multiple QTLs, 8 intervals were found to affect related traits under the two water supply conditions and 3 intervals were observed to be water supply-specific regions and had effects only under well-watered conditions, suggesting that water supply-specific regions or QTLs may be closely associated with the responses of lines to water deficit in the study. Several regions for the traits studied were also found to affect the root-related traits in previous studies and might be used in marker-assisted selection for drought-resistant rice in breeding programs.     

QTLs and Candidate Genes for Rice Root Growth Under Flooding and Upland Conditions

To investigate the genetic factors underlying constitutive and adaptive root growth under different water-supply conditions, a double haploid (DH) population, derived from a cross between lowland rice variety IR64 and upland rice variety Azucena, with 284 molecular markers was used in cylindrical pot experiments. Several QTLs for seminal root length (SRL), adventitious root number (ARN) and total root dry weight (RW) respectively, under both flooding and upland conditions were detected. Two identical QTLs for SRL and RW were found under flooding and upland conditions. The relative parameters defined as the ratio of parameters under the two water-supply conditions were also used for QTL analysis. A comparative analysis among different genetic populations was performed for the QTLs for root traits and several consistent QTLs for root traits across genetic backgrounds were detected. Candidate genes for cell expansion and elongation were used for comparative mapping with the detected QTLs. Four cell wall-related expressed sequence tags (ESTs) for OsEXP2, OsEXP4, EXT and Xet were mapped on the intervals carrying the QTLs for root traits.     

Mapping QTLs of root morphological traits at different growth stages in rice

Roots are a vital organ for absorbing soil moisture and nutrients and influence drought resistance. The identification of quantitative trait loci (QTLs) with molecular markers may allow the estimation of parameters of genetic architecture and improve root traits by molecular marker-assisted selection (MAS). A mapping population of 120 recombinant inbred lines (RILs) derived from a cross between japonica upland rice 'IRAT109' and paddy rice 'Yuefu' was used for mapping QTLs of developmental root traits. All plant material was grown in PVC-pipe. Basal root thickness (BRT), root number (RN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW) and root volume (RV) were phenotyped at the seedling (I), tillering (II), heading (III), grain filling (IV) and mature (V) stages, respectively. Phenotypic correlations showed that BRT was positively correlated to MRL at the majority of stages, but not correlated with RN. MRL was not correlated to RN except at the seedling stage. BRT, MRL and RN were positively correlated to RFW, RDW and RV at all growth stages. QTL analysis was performed using QTLMapper 1.6 to partition the genetic components into additive-effect QTLs, epistatic QTLs and QTL-by-year interactions (Q x E) effect. The results indicated that the additive effects played a major role for BRT, RN and MRL, while for RFW, RDW and RV the epistatic effects showed an important action and Q x E effect also played important roles in controlling root traits. A total of 84 additive-effect QTLs and 86 pairs of epistatic QTLs were detected for the six root traits at five stages. Only 12 additive QTLs were expressed in at least two stages. This indicated that the majority of QTLs were developmental stage specific. Two main effect QTLs, brt9a and brt9b, were detected at the heading stage and explained 19% and 10% of the total phenotypic variation in BRT without any influence from the environment. These QTLs can be used in breeding programs for improving root traits.     

QTLs for cell-membrane stability mapped in rice (Oryza sativa L.) under drought stress

Cell-membrane stability (CMS) is considered to be one of the major selection indices of drought tolerance in cereals. In order to determine which genomic region is responsible for CMS, 104 rice (Oryza sativa L.) doubled haploid (DH) lines derived from a cross between CT9993–5-10–1-M and IR62266-42–6-2 were studied in the greenhouse in a slowly developed drought stress environment. Drought stress was induced on 50-day-old plants by withholding water. The intensity of stress was assessed daily by visual scoring of leaf wilting and by measuring leaf relative water content (RWC). The leaf samples were collected from both control (well-watered) and stressed plants (at 60–65% of RWC), and the standard test for CMS was carried out in the laboratory. There was no significant difference (P>0.05) in RWC between the two parental lines as well as among the 104 lines, indicating that all the plants were sampled at a uniform stress level. However, a significant difference (P<0.05) in CMS was observed between the two parental lines and among the population. No significant correlation was found between CMS and RWC, indicating that the variation in CMS was genotypic in nature. The continuous distribution of CMS and its broad-sense heritability (34%) indicates that CMS should be polygenic in nature. A linkage map of this population comprising of 145 RFLPs, 153 AFLPs and 17 microsatellite markers was used for QTL analysis. Composite interval mapping identified nine putative QTLs for CMS located on chromosomes 1, 3, 7, 8, 9, 11 and 12. The amount of phenotypic variation that was explained by individual QTLs ranged from 13.4% to 42.1%. Four significant (P<0.05) pairs of digenic interactions between the detected QTLs for CMS were observed. The identification of QTLs for this important trait will be useful in breeding for the improvement of drought tolerance in rice. This is the first report of mapping QTLs associated with CMS under a natural water stress condition in any crop plants. Received: 8 September 1999 / Accepted: 13 October 1999     

Comparison of QTL controlling seedling vigour under different temperature conditions using recombinant inbred lines in rice (Oryza sativa)

BACKGROUND AND AIMS: Seedling vigour is one of the major determinants for stable stand establishment in rice (Oryza sativa), especially in a direct seeding cropping system. The objectives of this study were to identify superior alleles with consistent effects on seedling vigour across different temperature conditions and to investigate genotype x environmental temperature interactions for seedling vigour QTL. METHODS: A set of 282 F13 recombinant inbred lines (RILs) derived from a rice cross were assessed for four seedling vigour traits at three temperatures (25 degrees C, 20 degrees C and 15 degrees C). Using a linkage map with 198 marker loci, the main-effect QTL for the traits were mapped by composite interval mapping. KEY RESULTS: A total of 34 QTL for the four seedling vigour traits were identified. Of these QTL, the majority (82%) were clustered within five genomic regions, designated as QTL qSV-3-1, qSV-3-2, qSV-5, qSV-8-1 and qSV-8-2. All of these five QTL had small individual effects on the traits, explaining 3.1-15.8 % of the phenotypic variation with a mean of 7.3 %. QTL qSV-3-1, qSV-3-2 and qSV-8-1 showed almost consistent effects on the traits across all three temperatures while qSV-5 and qSV-8-2 had effects mainly at the 'normal' temperatures of 20 degrees C and 25 degrees C. Among the five QTL identified, all and four showed additive effects on shoot length and germination rate, respectively. The contributions of these five QTL to shoot length and germination rate were also much larger than those to the other two traits. CONCLUSIONS: A few of genomic regions (or QTL) were identified as showing effects on seedling vigour. For these QTL, significant genotype x environmental temperature interactions were found and these interactions appeared to be QTL-specific. Among the four seedling vigour traits measured, shoot length and germination rate could be used as relatively good indicators to evaluate the level of seedling vigour in rice.     

Mapping QTLs and candidate genes for rice root traits under different water-supply conditions and comparative analysis across three populations

To investigate the genetic factors underlying constitutive and adaptive morphological traits of roots under different water-supply conditions, a recombinant inbred line (RIL) population derived from a cross between the lowland rice variety IR1552 and the upland rice variety Azucena with 249 molecular markers, was used in cylindrical-pot experiments. Eighteen QTLs were detected for seminal root length (SRL), adventitious root number (ARN), and lateral root length (LRL) and lateral root number (LRN) on the seminal root at a soil depth of from 3 to 6 cm under flooding and upland conditions. One identical QTL was detected under both flooding and upland conditions. The relative parameters under the two water-supply conditions were also used for QTL analysis. Five QTLs for upland induced variations in the traits were detected with the positive alleles from Azucena. A comparative analysis was performed for the QTLs detected in this study and those reported from two other populations with Azucena as a parent. Several identical QTLs for root elongation were found across the three populations with positive alleles from Azucena. Candidate genes were screened from ESTs and cDNA-AFLP clones for comparative mapping with the detected QTLs. Two genes for cell expansion, OsEXP2 and endo-1,4--D-glucanase EGase, and four cDNA-AFLP clones from root tissues of Azucena, were mapped on the intervals carrying the QTLs for SRL and LRL under upland conditions, respectively.Communicated by H.C. Becker     

Toward the mapping of physiological and agronomic characters on a rice function map: QTL analysis and comparison between QTLs and expressed sequence tags

We have constructed a rice function map by collating the results on quantitative trait loci (QTLs) for 23 important physiological and agronomic characters (including 13 newly measured traits) obtained using backcross inbred lines of japonica Nipponbare×indica Kasalath. Using these materials, The Rice Genome project (RGP) has developed a high-density genetic map. QTLs controlling yield did not overlap with those controlling the morphological and physiological traits supposed to relate to yield, such as photosynthetic ability. This result suggests that these traits do not influence yield, at least in this genetic background and environment. QTLs controlling yield also did not overlap with the structural genes controlling carbon metabolism (rbcS, cytosolic or plastidic fructose-1,6-bisphosphate, R-enzyme, and sucrose synthase).The combination of a function map and results from the RGP can be advantageous. The utility of this map is discussed. Received: 1 October 1999 / Accepted: 28 July 2000     

Genetic analysis and gene mapping of a rice few-tillering mutant in early backcross populations ( Oryza sativa L.)

A rice mutant,G069, characteristic of few tiller numbers, was found in anther culture progeny from theF ₁ hybrid between anindica-japonica cross, Gui630×02428. The mutant has another two major features: delayed tillering development and yellowing apex and margin on the mature leaves. As a donor parent,G069 was further backcrossed with the recurrent parent,02428, for two turns to develop aBC ₂F₂ population. Genetic analysis in theBC ₂F₂ population showed that the traits of few-tillering and yellowing apex and margin on the mature leaves were controlled by one recessive gene. A pool of equally mixed genomic DNA, from few-tillering individual plants inBC ₂F₂, was constructed to screen polymorphism with simple sequence repeat (SSR) markers in comparison with the02428 genome. One SSR marker and three restriction fragment length polymorphism (RFLP) markers were found possibly linked with the recessive gene. By using these markers, the gene of few-tillering was mapped on chromosome 2 between RFLP marker C424 and S13984 with a genetic distance of 2.4 cM and 0.6 cM, respectively. The gene is designatedft1.     

RFLP mapping of QTLs for yield and related characters in rice (Oryza sativa L.)

Quantitative triat loci (QTLs) for yield and related traits in rice were mapped based on RFLP maps from two indica/indica F₂ populations, Tesanai 2/CB and Waiyin 2/CB. In Tesanai 2/CB, 14 intervals carrying QTLs for eight traits were detected, including 3 for grain weight per plant (GWT), 2 for number of panicles per plant (NP), 2 for number of grains per panicle (NG), 1 for total number of spikelets per panicle (TNS), 1 for spikelet fertility (SF), 3 for 1000-grain weight (TGWT), 1 for spikelet density (SD), and 1 for number of first branches per main panicle. The 3 QTLs for GWT were located on chromosomes 1, 2, and 4, with 1 in each chromosome. The additive effect of the single locus ranged from 2.0 g to 9.1 g. A major gene (np4) for NP was detected on chromosome 4 within the interval of RG143–RG214, about 4cM for RG143, and this locus explained 26.1% of the observed phenotypic variance for NP. The paternal allele of this locus was responsible for reduced panicles per plant (3 panicles per plant). In another population, Waiyin 2/CB, 12 intervals containing QTLs for six of the above-mentioned traits were detected, including 3 for GWT, 2 for each of NP, TNS, TGWT and SD, 1 for SF. Three QTLs for GWT were located on chromosome 1, 4, and 5, respectively. The additive effect of the single locus for GWT ranged from 6.7 g to 8.8 g, while the dominance effect was 1.7–11.5 g. QTL mapping in two populations with a common male parent is compared and discussed.     

A "defeated" rice resistance gene acts as a QTL against a virulent strain of Xanthomonas oryzae pv. oryzae

The genetic components responsible for qualitative and quantitative resistance of rice plants to three strains (CR4, CXO8, and CR6) of Xanthomonas oryzae pv. oryzae (Xoo) were investigated using a set of 315 recombinant inbred lines (RILs) from the cross Lemont (japonica) × Teqing (indica) and a complete linkage map with 182 well distributed RFLP markers. We mapped a major gene (Xa4) and ten quantitative trait loci (QTLs) which were largely responsible for segregation of the resistance phenotype in the RILs. The Teqing allele at the Xa4 locus, Xa4 ^T , acted as a dominant resistance gene against CR4 and CXO8. The breakdown of Xa4 ^T -associated resistance mediated by the mutant allele at the avrXa4 locus in the virulent strain CR6 results from significant changes in both gene action (lose of dominance) and the magnitude of gene effect (≈50% reduction). Nevertheless, Xa4 ^T still acted as a recessive QTL with a significant residual effect against CR6. The mutant alleles at the avrXa4 locus in CXO8 and CR6 that lead to a reduction in effect, or “breakdown”, of Xa4 ^T were apparently accompanied by corresponding penalties for their fitness. The quantitative component of resistance to Xoo in the RILs was largely due to a number of resistance QTLs. Most resistance QTLs mapped to genomic locations where major resistance genes and/or QTLs for resistance to Xoo, blast and sheath blight were identified in the same cross. Most QTLs showed consistent levels of resistance against all three Xoo strains. Our results suggest that a high level of durable resistance to Xoo may be achieved by the cumulative effects of multiple QTLs, including the residual effects of “defeated” major resistance genes. Received: 28 April 1998 / Accepted: 9 October 1998     

应用分子标记研究氮素胁迫条件下水稻叶片叶绿素含量差异的遗传背景

在氮素限制供应条件下,灿稻品种ＩＲ４２与广亲合粳稻品种Ｐａｌａｗａｎ剑叶及下位叶的平均叶绿素含量差异显著,叶绿素含量在Ｐａｌａｗａｎ／ＩＲ４２杂交Ｆ２代中呈正态分布,１０４个分布与１２条染色体的ＲＦＬＰ标记基因型之间表型平均值方差分析与区间作图分析结果表明,分别位于染色体２,４,７上的３个ＱＴＬ位于ＲＺ５８／ＲＧ１０２,ＲＧ１４３／ＲＧ３２９和ＲＧ６３４／ＲＧ６５０之间。与ＲＧ１４３及ＲＧ１０２连     

一个新的水稻叶绿素缺失黄叶突变体的特征及基因分子定位

从粳稻"嘉花1号"60Coγ射线辐照的后代中筛选到一个叶绿素缺失黄叶突变体(yl11),与野生型"嘉花1号"相比该突变体表现为全生育期植株叶片呈黄色,叶绿素含量以及净光合速率明显下降,叶绿体发育不完善,并且伴随着株高等主要农艺性状的变化。遗传分析表明,该突变性状受一对隐性核基因(yl11)控制。该突变体与籼稻"培矮64S"杂交生产的F2、F3群体中的分离出突变体型920个单株作为定位群体,利用SSR和InDel分子标记将yl11基因定位在水稻第11染色体长臂上的MM2199和ID21039分子标记之间,其物理距离约为110kb,目前该区域内没有发现与水稻叶绿素合成/叶绿体发育相关已知功能基因。研究结果为今后对该基因的克隆和功能分析奠定了基础。     

Developmental behavior of gene expression for brown rice thickness under different environments

The dynamic changes of genetic effects, including main effects, and genotype x environment (GE) interaction effects on brown rice thickness (BRT) across environments were investigated by using the developmental genetic models. Seven cytoplasmic male sterile lines of indica rice (Oryza sativa L.) as females and five restoring lines as males were used in a factorial design to produce grains of F(1)s and F(2)s in two environments (years) for developmental genetic analysis. The results indicate that genetic effects, especially GE interaction effects of triploid endosperm genes, cytoplasm genes, and diploid maternal plant genes were important to the performance of BRT at various filling stages of rice. The BRT was genetically controlled by the net genetic effects of genes expressed at the early and late filling stages (1-7 days and 15-21 days after flowering, respectively). The differences in net genetic effects under different environments for endosperm, cytoplasm, and maternal plant genes were found, and the net GE interaction effects were more important to BRT at the early filling and mature stages of rice. Some net genetic effects, especially for net cytoplasm effects spasmodically expressed, were detected among filling stages. Higher additive and cytoplasm main effects, along with their interaction effects, were found, which would be useful for selection for BRT in breeding programs. The predicated genetic effects at different filling stages show that the parents of V20 and Xieqingzao were better than others for improving BRT of progenies.     

不同生态条件下华抗草78水稻对杂草的干扰控制作用

对不同水稻叶龄、水层深度、水稻密度和保水时间条件下水稻对杂草控制效果进行研究.结果表明,具有化感特性的水稻品系华抗草78对稗草、鳢肠、异型莎草等杂草的抑制率显著优于无化感特性品种Lemont;华抗草78对0～1.5叶期稗草和0～0.3叶期异型莎草的控制效果优于1.5～2.4叶期稗草和0.8～2.0叶期异型莎草;移栽时叶龄与栽插密度互作有利于提高华抗草78对杂草的防效,并明显高于移栽时叶龄分别与水层深度和保水时间互作效应.适当提高水稻移栽时的叶龄、增加移栽密度可显著提高华抗草78对供试杂草的抑制率.     

水稻籼粳交DH群体收获指数及源库性状的QTL分析

以 1个水稻籼粳交 (圭 6 30 0 2 4 2 8)来源的DH群体为材料 ,利用 1张含有 2 32个标记的RFLP连锁图谱和基于混合线性模型的定位软件QTLMapper1 0对水稻收获指数及生物量、籽粒产量、库容量和株高 5个性状进行QTL分析 ,共检测到 2 1个主效应QTLs和 9对上位性互作位点。其中 ,控制籽粒产量的 3个QTLs合计贡献率为 4 2 % ,LOD值为 7 10 ;这 3个QTLs或者与收获指数的QTL同位 ,或者与生物量的QTL同位 ,且加性效应的方向一致 ,从而揭示了“籽粒产量 =生物量×收获指数”的遗传基础所在。控制收获指数的 4个QTLs合计贡献率为 4 6 % ,LOD值为 10 3;控制生物量的 4个QTLs合计贡献率为 6 4 % ,LOD值为 14 0 9;收获指数的 4个QTLs与生物量的 4个QTLs均不同位。因此 ,通过基因重组 ,可能实现控制收获指数和生物量的增效基因的聚合 ,由此获得收获指数和生物量“双高”的基因型。检测到 5个株高QTLs,其合计贡献率为 6 4 % ,LOD值为 11 6 2 ;其中 ,有 3个效应较小的QTLs与生物量、库容量和 或籽粒产量QTLs同位 ,且同位QTLs的加性效应方向一致 ;未发现株高QTLs与收获指数QTLs的同位性。由此表明 ,株高与“源 流 库”概念中的“源”和“库”在遗传上有一定程度的关联 ,而与“流”无关联。此外还发现 ,在上述同位性QTL     

Mapping QTLs for phosphorus deficiency tolerance in rice (Oryza sativa L.)

 The amplified fragment length polymorphism (AFLP) technique combined with selective genotyping was used to map quantitative trait loci (QTLs) associated with tolerance for phosphorus (P) deficiency in rice. P deficiency tolerant cultivar IR20 was crossed to IR55178-3B-9-3 (sensitive to P-deficiency) and 285 recombinant inbred lines (RILs) were produced by single-seed descent. The RILs were phenotyped for the trait by growing them in P-sufficient (10.0 mg/l) and P-deficient (0.5 mg/l) nutrient solution and determining their relative tillering ability at 28 days after seeding, and relative shoot dry weight and relative root dry weight at 42 days after seeding. Forty two of each of the extreme RILs (sensitive and tolerant) and the parents were subjected to AFLP analysis. A map consisting of 217 AFLP markers was constructed. Its length was 1371.8 cM with an average interval size of 7.62 cM. To assign linkage groups to chromosomes, 30 AFLP and 26 RFLP markers distributed over the 12 chromosomes were employed as anchor markers. Based on the constructed map, a major QTL for P-deficiency tolerance, designated PHO, was located on chromosome 12 and confirmed by RFLP markers RG9 and RG241 on the same chromosome. Several minor QTLs were mapped on chromosomes 1, 6, and 9. Received: 21 April 1998 / Accepted: 9 June 1998