不同环境下水稻谷粒重发育的杂种优势和遗传相关性分析

选用9个不同类型的水稻品种(系),按双列杂交设计(6×5)配成两套亲本和F12个世代的遗传材料,采用数量性状的加性、显性遗传模型、发育遗传模型比较分析了水稻谷粒重发育的杂种优势和遗传相关性。结果表明,早季在谷粒充实前期(1～12d)群体平均优势较小,中后期(13～28d)正向优势趋于明显,在谷粒充实的全过程均表现较小的负向群体超亲优势;晚季则在谷粒充实前中期(1～18d)表现正向群体平均优势。后期(19～28d)优势不明显,在谷粒充实前期(1～12d)表现正向群体超亲优势,之后转为明显的负向群体超亲优势,表明晚季谷粒发育的杂种优势表现较之早季更有利于提高籽粒充实质量,不同发育时期谷粒重之间以及与最终谷粒重之间的遗传相关分析表明,早季以显性相关为主,晚季以加性相关为主,随着发育进程的推进,相关趋于密切。     

Haploid and diploid plant regeneration from protoplasts of anther callus in rice

Summary The regeneration of haploid and diploid plants was demonstrated from protoplasts that were isolated from cell suspensions of anther callus in rice. The cell suspension in the AA medium that contained 4 amino acids as the sole nitrogen source was friable, finely dispersed, and readily released a large number of protoplasts. These protoplasts, subsequently cultured in NO₃ medium that contained nitrate as the sole nitrogen source, formed compact calli. The compact calli produced green plants with a frequency of 24%. Out of 15 flowering plants, 4 were haploids, the others were diploids which showed a uniform morphology but varied in seed fertility from 95 to 0%.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid     

Large-scale deletions of rice plastid DNA in anther culture

Summary Plastid DNA (ptDNA) in albino rice plants regenerated from pollen by anther culture was investigated by Southern blotting. Of the 20 albino plants investigated, 7 contained ptDNA that had suffered large-scale deletion. The size and location of the deletions differed among the plants. In all cases about 30 kbp of the region containing the PstI-2 fragment (15.7 kbp) had been retained. The deleted ptDNA molecules were retained in calluses derived from the roots of each albino plant.     

Variation for improved protein and yield from rice anther culture

Summary The anther culture technique is useful for the recovery of haploids which when doubled provide homozygosity. Additionally, beneficial as well as deleterious genetic and epigenetic changes are promoted by the in vitro procedures. The majority of plants recovered from anther calli of the cultivar Calrose 76 were similar to the starting cultivar but plants regenerated from microspore calli had a wider range of responses than controls for several characteristics. Plants with larger seeds, higher levels of seed protein, shorter stature and more highly tillered than the starting cultivar were obtained from selfed anther-derived plants. The data also support the concept that in vitro procedures including anther culture of specific cultivars of rice promoted the recovery of phenotypes with increased seed storage proteins.Contribution from the U.S. Department of Agriculture, Science and Education, Agricultural Research Service, Plant Physiology Institute, Tissue Culture and Molecular Genetics Laboratory, Room 116, Building 011-A, BARC-West, Beltsville, Maryland 20705, USA     

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.     

Gametic selection in anther culture of rice (Oryza sauva L.)

Summary The segregation and recombination of heterozygous isozyme markers have been monitored in anther culture derivatives (i.e., six nonmorphogenic microspore-derived callus [NMC] populations and two anther culture plant [ACP] populations) and F₂ plants generated from six F₁ hybrids of rice, including five japonica upland/improved indica tropical hybrids. The alleles in excess at some loci displaying skewed segregations in the F₂s were consistently overrepresented in the NMC populations. These alleles were also generally found to be overabundant in the two ACP populations except for certain loci that contrastingly segregated in a 11 ratio. Additional distortions were found to be specific to AC derivatives indicating the existence of in vitro gametic selection. Overall, however, the gametic selection in the ACP materials was neutral with regard to the indica and japonica differentiation. Estimates of linkages between markers borne by chromosome 6 using AC-derivative data were consistent with those noted in the F₂s and with current knowledge of the isozyme locus linkage map. Given the average neutrality of gametic selection and the consistency of linkage relationships in the ACPs, their further use as rice molecular mapping and gene tagging populations can be investigated with confidence.Joint contribution with Research Institute for Tropical Food Crops, Department of the International Centre of Agronomical Research for Development (IRAT-CIRAD), 45bis avenue de la Belle Gabrielle, F-94736 Nogent s/Marne Cédex, France and International Rice Research Institute (IRRI), P.O.Box 933, Manila, Philippines     

花粉发育的转录组研究进展

在受精过程中花粉通过其极性生长的花粉管将精细胞运送到胚囊启动双受精，除了在有性生殖过程中的重要作用外，花粉及其极性生长的花粉管也是研究植物生长发育的重要模式材料。随着模式植物拟南芥和水稻基因组测序的完成，在基因组水平上揭示花粉发育以及花粉管极性生长的分子基础已成为可能。经过最近几年的研究已初步明确了花粉转录组特征。本文主要讨论了拟南芥花粉转录组学的研究进展，以期帮助读者对花粉发育的研究有全面了解。     

Establishment of stable NaCl-resistant rice plant lines from anther culture: distribution pattern of K+/Na+ in callus and plant cells

 Soil salinity markedly suppresses the growth of rice (Oryza sativa L.). We established rice anther culture to select for rice callus lines adapted to NaCl stress and regenerated plant progenies resistant to a NaCl stress of E.C. 16–18 mS. When exposed to NaCl, NaCl-adapted rice calli lost K⁺ and accumulated little Na⁺. Conversely, plant cells lost relatively little K⁺ and accumulated Na⁺. It is plausible that, NaCl-resistant mechanisms are different at callus and plant level. The stable NaCl-resistant lines produced have potential use in elucidating the molecular mechanisms behind NaCl resistance in rice and in rice breeding. Received: 27 February 1997 / Accepted: 4 April 1997     

Proteome analysis of male gametophyte development in rice anthers

We used proteomic analysis to investigate the changing patterns of protein synthesis during pollen development in anthers from rice plants grown under strictly controlled growth conditions. Cytological analysis and external growth measurements such as anther length, auricle distances and days before flowering were used to determine pollen developmental stages. This allowed the collection of synchronous anther materials representing six discrete pollen developmental stages. Proteins were extracted from the anther samples and separated by two-dimensional gel electrophoresis to produce proteome maps. The anther proteome maps of different developmental stages were compared and 150 protein spots, which were changed consistently during development, were analysed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry to produce peptide mass fingerprint (PMF) data. Database searches using these PMF data revealed the identities of 40 of the protein spots analyzed. These 40 proteins represent 33 unique gene products. Four protein spots that could not be identified by PMF analysis were analysed by N-terminal microsequencing. Multiple charge-isoforms of vacuolar acid invertase, fructokinase, beta-expansin and profilin were identified. These proteins are closely associated with sugar metabolism, cell elongation and cell expansion, all of which are cell activities that are essential to pollen germination. The existence of multiple isoforms of the same proteins suggests that during the process of pollen development some kind of post-translational modification of these proteins occurs.     

花药培养过程栽培稻花粉不育杂种F1与亲本台中65的细胞学研究

利用活体压片、半薄及超薄切片技术,对栽培稻(Oryza sativa L.)花粉不育杂种F1及育性正常的亲本台中65离体培养前后的小孢子及花药壁进行细胞学研究.结果表明:与台中65相比,杂种F1的花粉小孢子在发育至单核中-晚期,出现比例较高的胞质凝聚小孢子和少量星型小孢子,正常小孢子和淀粉化小孢子比例降低.在离体条件下,胞质凝聚小孢子、星型小孢子、正常小孢子、液泡化小孢子、淀粉化小孢子的发育主要沿着胞质凝聚败育过程、孢子体发育过程、配子体发育过程、液泡化过程和淀粉化过程进行;药壁组织在离体条件下,杂种F1比台中65的绒毡层降解速度快,中层膨大程度高.杂种F1与台中65在离体培养下小孢子发育及药壁细胞学的差异主要是受到S-a座位内等位基因互作及离体培养环境的影响.     

Quantitative trait loci analysis for the developmental behavior of tiller number in rice (Oryza sativa L.)

 A doubled-haploid rice population of 123 lines from Azucena/IR64 was used for analyzing the developmental behavior of tiller number by conditional and unconditional QTL mapping methods. It was indicated that the number of QTLs significantly affecting tiller number was different at different measuring stages. Many QTLs controlling tiller growth identified at the early stages were undetectable at the final stage. Only one QTL could be detected across the whole growth period. By conditional QTL mapping, more QTLs for tiller number could be detected than that by unconditional mapping. The temporal patterns of gene expression for tiller number could be different at different stages. Even an individual gene or genes at the same genomic region might have opposite genetic effects at various growth stages. Received: 7 July 1997 / Accepted: 10 February 1998     

Calcium distribution in fertile and sterile anthers of a photoperiod-sensitive genic male-sterile rice

Potassium antimonate was used to locate Ca²⁺ in fertile and sterile anthers of a photoperiod-sensitive genic male-sterile rice (Oryza sativa L. japonica). During the development of fertile anthers, abundant calcium precipitates accumulated in the anther walls and on the surface of pollen grains and Ubish bodies at the late developmental stage of the microspore, but not in the cytoplasm of pollen grains. Following the accumulation of starch grains in pollen, calcium precipitates on pollen walls diminished and increased in parenchymatous cells of the connective tissue. In sterile anthers, calcium precipitates were abundant in the middle layer and endothecium, but not in the tapetum, as was found in fertile anthers. A special cell wall was observed between the tapetum and middle layer of sterile anthers that appeared to relate to distinctive calcium accumulation patterns and poor pollen wall formation in the loculi. The formation of different patterns of antimonate-induced calcium precipitates in the anthers of photoperiod-sensitive genic male-sterile rice indicates that anomalies in the distribution of calcium accumulation correlate with the failure of pollen development and pollen abortion. Received: 30 May 1997 / Accepted: 5 July 1997     

ABCB1 and ABCB19 auxin transporters have synergistic effects on early and late Arabidopsis anther development

Arabidopsis abcb1 abcb19 double mutants defective in the auxin transporters ABCB1/PGP1 and ABCB19/PGP19 are altered in stamen elongation, anther dehiscence and pollen maturation. To assess the contribution of these transporters to stamen development we performed phenotypic, histological analyses, and in situ hybridizations on abcb1 and abcb19 single mutant fl owers. We found that pollen maturation and anther dehiscence are precocious in the abcb1 but not in the abcb19 mutant. Accordingly, endothecium ligni fication is altered only in abcb1 anthers. Both abcb1 and abcb1 abcb19 stamens also show altered early development, with asynchronous anther locules and a multilayer tapetum. DAPI staining showed that the timing of meiosis is asynchronous in abcb1 abcb19 anther locules, while only a small percentage of pollen grains are nonviable according to Alexander's staining. In agreement, TAM(TARDY ASYNCHRONOUS MEIOSIS), as well as BAM2(BARELY ANY MERISTEM)—involved in tapetal cell development—are overexpressed in abcb1 abcb19 young fl ower buds. Corre spondingly, ABCB1 and ABCB19 mRNA localization supports the observed phenotypes of abcb1 and abcb1 abcb19 mutant anthers. In conclusion, we provide evidence that auxin transport plays a signi ficant role both in early and late stamen development: ABCB1 plays a major role during anther development, while ABCB19 has a synergistic role.     

Comparison of single seed descent and anther culture-derived lines of three single crosses of rice

Summary Distribution parameters (mean, variance, skewness and kurtosis) of 12 quantitative traits were evaluated for inbred lines generated through single seed descent (SSD) and anther culture (AC) of two japonica x japonica hybrids and one japonica x indica hybrid of rice. For most of the traits the data were normally distributed, and the means and variances were found to be identical for SSD- and AC-derived lines of the given hybrids. However, for some other traits, differences between the two population types were observed, mainly in the lines derived from the intra-japonica crosses. A tentative explanation for these differences is given. Nevertheless, our results suggest that SSD and AC are equally effective breeding techniques for producing agronomically useful lines of rice.     

Magnitude of hybrid vigor retained in double haploid lines of some heterotic rice hybrids

Sixty one double haploid (DH) lines were evaluated for yield components and yield and compared with the three corresponding hybrids from which they were derived through anther culture. Analysis of a 6×6 diallel experiment led to the selection of these hybrids based on their high heterosis and revealed the nature of gene action of the characters under evaluation. The DH lines along with the hybrids and parents were planted following a simple lattice design with two replications. The results show that in DH lines the values of the characters expressing predominantly additive genetic effects could reach the heterotic level of the hybrids. For characters including yield showing predominantly dominance effects, values in the DH lines were significantly lower than those of the corresponding hybrids. The promising DH lines, however, possess a higher yield potential than the better parents.     

Overexpression of rice phytochrome A partially complements phytochrome B deficiency in Arabidopsis

The red/far-red reversible phytochromes play a central role in regulating the development of plants in relation to their light environment. Studies on the roles of different members of the phytochrome family have mainly focused on light-labile, phytochrome A and light-stable, phytochrome B. Although these two phytochromes often regulate identical responses, they appear to have discrete photosensory functions. Thus, phytochrome A predominantly mediates responses to prolonged far-red light, as well as acting in a non-red/far-red-reversible manner in controlling responses to light pulses. In contrast, phytochrome B mediates responses to prolonged red light and acts photoreversibly under light-pulse conditions. However, it has been reported that rice (Oryza sativa L.) phytochrome A operates in a classical red/far-red reversible fashion following its expression in transgenic tobacco plants. Thus, it was of interest to determine whether transgenic rice phytochrome A could substitute for loss of phytochrome B in phyB mutants of Arabidopsis thaliana (L.) Heynh. We have observed that ectopic expression of rice phytochrome A can correct the reduced sensitivity of phyB hypocotyls to red light and restore their response to end-of-day far-red treatments. The latter is widely regarded as a hallmark of phytochrome B action. However, although transgenic rice phytochrome A can correct other aspects of elongation growth in the phyB mutant it does not restore other responses to end-of-day far-red treatments nor does it restore responses to low red:far-red ratio. Furthermore, transgenic rice phytochrome A does not correct the early-flowering phenotype of phyB seedlings. Received: 12 July 1998 / Accepted: 13 August 1998     

Comparative genetic maps of foxtail millet (Setaria italica) and rice (Oryza sativa)

 A foxtail millet-rice comparative genetic map was constructed using mapped rice RFLP markers and wheat genomic and cDNA clones with known map position in rice. About 74% and 37% of the cDNA and genomic clones, respectively, were transferable to foxtail millet, confirming that conservation at the DNA level is greatest in genic regions. A high degree of conserved colinearity was observed between the two genomes. Five entire foxtail millet chromosomes appear to be colinear with five entire rice chromosomes. The remaining four foxtail millet linkage groups each show colinearity with segments of two rice chromosomes. The rearrangements of rice chromosomes 3 and 10 to form foxtail millet chromosome IX, and 7 and 9 to form chromosome II are very similar to those required to form maize chromosomes 1 and 7 and sorghum linkage groups C and B, indicating Setaria’s clear taxonomic position within the subfamily of the Panicoideae. Received: 18 December 1996 / Accepted: 4 August 1997