Anther culture of recalcitrant indica × Basmati rice hybrids

Fertile, green, di-haploid plants were obtained at high frequencies from several indica × Basmati rice F₁ hybrids and/or F₂ plant populations using an improved anther culture procedure. Anthers from cold-pretreated (10 ^°C for 10 d) panicles of six indica (HKR120, HKR86-3, HKR86-217, PR106, Gobind andCH2 double dwarf) and two Basmati rice (Basmati 370,Taraori Basmati) varieties and 14 heterotic indica ×Basmati F₁/F₂ hybrids were cultured in modified agarose-solidified N6M, Heh5M and RZM media. Best callus induction frequencies (2.6–78%) were obtained in RZM medium containing 4% (w/v) maltose,2,4-D, NAA and kinetin. F₂ plants compared to F₁ hybrids and parental rice varieties, were more responsive to anther culture. Androgenesis frequencies of 31–78% were obtained for indica × Basmati F₂ plants in RZM medium in just 30 d which are comparable to or higher than that reported for japonica rice varieties and hybrids involving japonica rice parent(s). Agarose (1.0% w/v)-solidified MS medium containing 3.0% maltose, kinetin, BAP, and NAA, induced green shoot regeneration in 0–51% of the anther-derived callide pending upon the genotype. High plant regeneration frequencies (67–337 green plants per 1000 anthers)were obtained from anther calli of several F₁hybrids (Gobind × Basmati 370 and HKR120 ×Taraori Basmati) and F₂ plants (Gobind × Basmati370, Gobind × Taraori Basmati, HKR86-3 × TaraoriBasmati). A sample of 498 plants obtained from the above hybrids, were transferred to pots with>90% survival; 8–78% of these plants had >5%spikelet fertility and were diploid. In addition,18% of the haploid plants could be diploidized by submerging in 0.1% colchicine solution for 16–18 h. The improved anther culture procedure reported here, resulted in several fold increase in the recovery of green plants from recalcitrant indica × Basmati rice hybrids compared to previous published procedures. The study may accelerate the introgression of desirable genes from indica into Basmati rice using anther culture as a breeding tool. This revised version was published online in July 2006 with corrections to the Cover Date.     

水稻高秆突变体株高及其构成的比较和等位性分析

利用伽玛射线辐射诱变获得了2份高秆突变体Gh-2和Sh-3,对它们的株高及其各节间长、穗长等的变化进行了分析.以同样是高秆的突变体Mh-1做测验种与Gh-2和Sh-3进行杂交,研究了相互间的等位性,研究结果认为它们是互为等位的遗传关系,即含有对sd-1能起隐性调节作用的i-sd1(t)基因.     

大麦半矮秆品种资源“米麦114”和“尺八大麦”的遗传评价

用大麦半矮秆品种资源米麦114和尺八大麦与高秆测验种Bowman杂交的P1、P2、F1、F2及B1和B2六个世代群体为试村，研究了这两份半矮秆资源株高等性状的遗传规律及其之间的遗传关系。发现它们的半矮生性状均主要受一对隐性基因控制；千粒重由微效多基因决定，符合基因的加性——显性遗传模式。米麦114的穗长和穗密度各受一对隐性     

成恢448与Basmati 370回交后代的米粒延伸性遗传和相关分析

对成恢448(CH448)与Basmati 370的BC₂F₅株系及其与5个不育系配制的杂种F₁,CH448和5个保持系的12个米质性状进行了多元偏相关、通径分析、对应分析和遗传分析。结果表明：（1）CH448和保持系等亲本12个米质性状之间的偏相关性不显著。BC₂F₅株系中,仅饭粒长（CRL）和     

Inheritance and allelism for resistance to Russian Wheat Aphid in an Iranian Spring Wheat

Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is an important pest of wheat (Triticum aestivum L.) in the United States of America. Developing adapted wheat cultivars with genetic resistance to RWA is an effective control strategy. Genetic studies were conducted to determine the mode of inheritance of gene(s) conferring resistance to RWA in an Iranian landrace wheat line, G 5864. For the inheritance study, G 5864 was crossed with the susceptible wheats ‘Yecora Rojo’ and ND 2375. Seedlings of F1, reciprocal F1, F2, BC1 to the susceptible parent (BCS), and BC1 to the resistant parent (BCR) were screened for RWA reaction. Several phenotypic segregation ratios were tested in the F2 populations for goodness of fit; the 9:3:3:1 ratio (resistant: rolled leaves: stunted plants: susceptible) was an acceptable fit in all cases. Thus, resistance in G 5864 seemed to be controlled by two independent dominant genes with additive gene effects. The allelic relationships of gene(s) in this line with genes in other resistant lines, PI 137739 (Dn1), PI 262660 (Dn2), PI 372129 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6), were also studied. Segregation patterns observed in G 5864 × resistant (R × R) F2 populations were inconclusive. However, no susceptible plants were observed in these F2 populations. If previous reports concerning the number of resistance genes present in the other resistant lines are correct, then given the high manifestation of resistance observed in G 5864, and given the absence of susceptible plants in the R × R F2 populations, it is indicated that RWA resistance in G 5864 is either controlled by different alleles at the same loci as the other resistance genes, or that G 5864 shares a resistance gene with each of the other resistant lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

First in vivo assessment of feeding value of Festulolium hybrids derived from Festuca arundinacea var. glaucescens and selection for palatability

This paper reports on the first results of feeding value experiments, assessed with sheep, of hybrids between tetraploid Italian ryegrass (Lolium multiflorum, 2n = 4×= 28) and a progenitor of tall fescue, Festuca arundinacea var. glaucescens (2n = 4×= 28). Three hybrid populations resulting from either high, low or no selection for palatability were compared with a variety of Italian ryegrass as control and two varieties of the cultivated hexaploid (2n = 6×= 42) tall fescue, one of which had been selected for high palatability. On average, the hybrid populations were found to be as palatable as the improved tall fescue with voluntary intake (VI), in vivo digestibility of organic matter (DOM), and net energy expressed in fodder units for milk, similar to the best palatable tall fescue and to Italian ryegrass. However, selection for improved palatability among hybrids did not result in any further improvement of other traits, except VI in the hybrid selected for high palatability which significantly exceeded VI of Italian ryegrass. In conclusion, intergeneric hybridization between L. multiflorum and F. arundinacea var. glaucescens led to an immediate increase of feeding value compared with selection for palatability in tall fescue. However, to improve feeding value of hybrids further, similar selection for high palatability appeared questionable and possibly detrimental for other agronomic traits because of complicated inheritance in tetraploid L. multiflorum×F. glaucescens hybrids.     

Effects of dwarfing genes on yield and yield components under irrigated and rainfed conditions in wheat (Triticum aestivum L.)

Summary Near-isogenic tall (no dwarfing gene), semidwarf (Rht1 or Rht2) and dwarf (Rht1 + Rht2 or Rht3) spring wheat lines were evaluated for yield and yield components under irrigated and rainfed conditions. Under irrigated conditions, the dwarf and the semidwarf lines exhibited a significant yield advantage over the tall lines. Under rainfed conditions, the semidwarf lines outyielded the tall as well as the dwarf lines. Percent yield reduction in response to drought stress was highest with the dwarfs and lowest with the tall lines. Dry matter production of the tall lines and that of the semidwarf lines did not differ significantly and both produced significantly more dry matter than the dwarf lines under irrigated as well as rainfed conditions. Plant height and kernel weight decreased with increasing degree of dwarfness while number of kernels per spikelet, harvest index and days to heading increased under both moisture regimes. The dwarfing genes did not have any significant influence on number of tillers/m² and spikelets per spike in either moisture regime.     

四个抗稻瘟病细胞突变体的抗性遗传分析

研究了4个细胞突变体对稻瘟病菌ZA15、ZB11、ZC1的抗性遗传，结果表明，88-331和88-334对ZA15、ZB11的抗性受2对重复显性基因控制，且与城堡1号至少有1对等位基因存在；对ZC15的抗性则由1对与城堡1号等位的显性基因控制；对ZG1的抗性则分别受2对与城堡1号不等位的重复显性基因控制。88-45对ZA15、ZB11、ZC15和ZG1的抗性分别由     

Inheritance of plant elongation ability at seedling stage in rice

Summary In a comparison of methods to study inheritance of plant elongation ability, 15-, 20-, 25-, 30-, and 35-day-old F₂ populations of a cross between Baisbish (floating variety) and IR42 (nonelongating semidwarf modern variety) of rice, (Oryza sativa L.) were subjected to 65 cm water depth for 7 days. Frequency distribution of plant height before and after submergence was obtained. Bimodal curves in 15-, 20- and 25-day-old populations gave good fits to 9:7 elongating: nonelongating plants, suggesting that elongation was due to two dominant complementary genes. Segregation in the 30-day-old population was not clear-cut. A seedling age of 20 days was subsequently chosen for further studies.Two F₂'s involving floating rice and a nonelongating semidwarf; four F₂'s involving floating rice and an elongating semidwarf; and two F₂'s involving elongating and nonelongating semidwarf parents were studied with 20-day-old seedlings in the same way. Floating rice combinations with nonelongating semidwarf parents as well as with elongating semidwarf parents segregated into 9:7 elongating: nonelongating ratio. It is possible that because elongating and nonelongating dwarf parents did not differ much in elongation ability at seedling age, their combination with floating rice parents provided similar segregation. The F₂ distributions for height in elongating and nonelongating dwarf cross combinations were continuous with one peak.Genetic constitution of parents proposed are Sd1 Sd1 El El for floating parents, sd1 sd1 El El for semidwarf elongating, and sd1 sd1 el el for dwarf nonelongating.     

籼稻多蘖矮半矮秆基因的遗传分析和基因定位

对籼稻标记基因系材料多蘖矮的遗传分析表明, 其矮生性状是由2对隐性半矮秆基因控制的,分别为sd1和一个新的半矮秆基因,该基因初步定名为sdt3。以多蘖矮与南京6号杂交F₂的分离群体为基础,应用SSR标记进行连锁分析,将半矮秆基因sdt3定位于第11染色体的SSR标记SSR98和SSR35之间,分别相距0.06 cM、0.13 cM,二者之间的物理距离约为93kb。以南京6号为轮回亲本与多蘖矮进行回交和自交获得由半矮秆基因sdt3控制的近等基因系（新多蘖矮）,以赤霉素处理表明由sdt3控制的半矮秆系新多蘖矮对赤霉素不敏感。     

Genetics of Panicle Exsertion in Cold-Tolerant Rice (Oryza sativa)

Four cold-tolerant rice varieties, viz. ‘Khonorullo’, ‘Namyi’, ‘Abor B’ and ‘Meghalaya-1’ were crossed with two cold-susceptible ones, viz. ‘Pusa 33’ and ‘Subhadra’ (DR92), in all possible combinations to study the inheritance of gene(s) governing panicle exsertion and their allelic relationship among cold-tolerant varieties. F₁ hybrids of all the crosses showed complete panicle exsertion indicating dominance of this trait. Segregation pattern of panicle exsertion in F₂ and backcrosses show that all the four cold-tolerant varieties possessed a single dominant gene designated as Ctr-1. Absence of segregation for panicle exsertion in an F₂ generation obtained from intercrosses of cold-tolerant varieties suggests that the dominant genes in all the four cultivars are allelic.     

Semi-dominant genes confer additive tolerance to metribuzin in narrow-leafed lupin (<Emphasis Type="Italic">Lupinus angustifolius</Emphasis> L.) mutants

Narrow-leafed lupin (Lupinus angustifolius L.) is a grain legume well-adapted to sandy acid soils in a Mediterranean climate. Improved metribuzin tolerance in lupin cultivars is considered essential to protect crops from herbicide damage in Australia. This paper reports on the inheritance of metribuzin tolerance in two induced mutants Tanjil-AZ-33 and Tanjil-AZ-55 over the susceptible wild type cv. Tanjil. Both mutants were highly tolerant to 800 g/ha metribuzin with no foliage damage, but cv. Tanjil died and reciprocal F₁ hybrids had intermediate tolerance with foliage damage. The F₂ populations of both crosses, Tanjil-AZ-33 × Tanjil and Tanjil-AZ-55 × Tanjil, had a segregation ratio of 1:2:1 for highly tolerant: damaged:dead plants. Progeny tests (F₃) of selected F₂ single plants confirmed that highly tolerant F₂ plants were homozygous and damaged F₂ plants were heterozygous. Clearly a single semi-dominant gene conferred metribuzin tolerance in both mutants. An allelism test revealed that the two mutants had two non-allelic tolerance genes with F₂ plants segregating in a 15:1 ratio for survival and death at 800 g/ha metribuzin. The tolerance gene in Tanjil-AZ-33 was designated as Mt3 and the gene in Tanjil-AZ-55 as Mt5. At 4,000 g/ha metribuzin, 1/16 of F₂ plants from the cross between the two mutants had no herbicide damage, suggesting the additive effects of the two tolerance genes, whilst the rest were damaged or dead. Combining these two tolerance genes, Mt3 and Mt5, increased tolerance further by approximately five-fold.     

Evaluation of breeding semidwarf rice by induced mutation and hybridization

Summary Semidwarf indica varieties of rice (Oryza sativa L.) were developed by induced mutation. They generally have a yield capacity equal to that of the semidwarf varieties (T(N)1, IR 8 and others) selected from hybridization. Genetic studies showed that semidwarf genes induced in the mutants and spontaneous ones in existing varieties are at the same locus. These semidwarf mutants, selected in Taiwan and from an American long-grain variety, Centura Patna 231, were compared with their parents, the semidwarf variety Dee-goe-woo-gen, T(N)1 and IR 8. The semidwarf mutants average about 35% shorter than their tall parents. The plant height is reduced by shortening five internodes from the top, while panicle length is not affected. The mutants, Dee-geo-woo-gen, and improved short-statured varieties had similar patterns of internode elongation. The mutants derived from varieties sensitive to photoperiod have lost the sensitivity. One more crop can be grown within a year. All induced and hybrid-derived semidwarf varieties were highly susceptible to bacterial leaf blight when Xanthomonas oryzae was inoculated although some of their parents were moderately resistant. The mutation rate from irradiation of this semidwarf gene was estimated to be 0.1% in I-kung-bau, a native variety of Taiwan. This particular type of mutation has not yet been reported in japonica varieties. However, several promising strains with reduced plant height, earlier maturity and more grain yielding were recently obtained from the California japonica variety, Calrose, by X-irradiation. The merits of mutation breeding in rice are discussed.     

耒阳多毛等几个水稻品种对白叶枯病的抗性遗传

有关稻白叶枯病的抗性遗传研究,自1967年日本的西村首次报道了第一个抗白叶枯病基因以来,迄今在水稻上总共发现并命名了12个位点上的15个抗白叶枯病基因。其中,4个显性基因 Xa-1、Xa-2、Xa-3;Xa-kg 包括两个复等位基因 Xa-1~h、Xa-kg~h 是由日本用日本的菌系鉴定和命名的~((37)),另5个显性抗病基因 Xa-4、Xa-6、Xa-7、Xa-10、     

桃杂种(F1)果实重量的遗传研究

对7个类型30个杂交组合桃杂种后代果实重量分布情况进行了研究,结果表明：桃不同组合类型中,大果×大果、大果×中果、中果×大果、中果×中果、中果×小果、大果实生和中果实生的杂种后代出现小果、中果、大果的分离比率分别为：0:2:1、1:4:1、1:4:1、2:3:1、1:6:3、2:4:1。桃果实的狭义遗传力为h2=0.4403,后代种果实重量偏小的现象明显。在不同组合类型中,以大果×大果和大果实生后代获得大果的比率较高,分别为30%和30.47%。在桃杂交育种中,用亲本果实重量的一般配合力相比较,以大久保为参照,可知,超过大久保的母本有：‘晚黄金’、‘岗山500号’和‘阳泉肉桃’;超过大久保的父本的有：‘明星’和‘阿尔巴特’。     

Hybrid chlorosis in wheat × rye crosses

Fourteen accessions of rye when crossed to Triticum aestivum cv. C 306 (Ne1ne2ch1Ch2) yielded chlorotic F1 hybrids and six accessions involved in hybrid combination with the same tester produced normal F1 hybrid plants. Two rye accessions, namely, EC 179188 and EC 143825 when crossed to the wheat lines HD 2329 (ne1Ne2ch1Ch2) and NI 5439 (ne1ne2ch1Ch2) also produced chlorosis. The hybrids between T. macha and two rye accessions produced normal plants. Variable degrees of chlorosis were observed among different wheat × rye F1 hybrids. It is suggested that the rye accessions producing chlorosis in combination with wheat cvs. C 306, HD 2329 and NI 5439 (all Ch2-carriers) carry one of the complementary genes for chlorosis. Gene symbol Chr1 is proposed for the chlorosis gene of rye.     

Development of advanced fragrant rice lines from MR269 × Basmati 370 through marker-assisted backcrossing

Fragrance in rice is an appealing attribute to consumers. The increasing demand for fragrant rice highlights the need to develop fragrant rice variety that suit the preference of local consumers in addition to reduce fragrant rice imports. Marker-assisted backcrossing (MABC) was employed to develop advanced fragrant rice lines from the cross between MR269 and Basmati 370. MR269 is a Malaysian high-yielding rice variety but non-fragrant and was used as recurrent parent whereas Basmati 370 is a well-known fragrant traditional rice variety and was used as donor parent for the fragrance gene. Two generations of backcrosses and a generation of selfing were conducted to introgress the fragrance gene and restore the recurrent parent genome in the backcross progenies. As a result, 14 advanced fragrant rice lines were developed. These advanced fragrant rice lines carried homozygous alleles for the fragrance gene, similar to Basmati 370. The average recovery of recurrent parent genome was 88.4%. Besides being fragrant, the advanced fragrant rice lines also had most of the morphological and agronomical traits similar to MR269. Grain quality of the advanced fragrant rice lines in terms of gelatinization temperature, amylose content and gel consistency are also similar to both parents. Besides, the advanced fragrant rice lines had 2-acetyl-1-pyrroline content similar to Basmati 370. MABC approach applied in this study has successfully introgressed the fragrance gene and accelerated the recovery of recurrent parent genome in advanced fragrant rice lines, therefore these lines can be delivered to the farmers and consumers for use in due time.     

水稻三明显性核不育基因的初步鉴定

2001年在福建省尤溪县西城镇凤元村进行两系核不育系育性鉴定时, 在SE21S/Basmati 370组合编号为S221的800多株F₂代分离群体中发现1株与其他不育株的花粉败育形态不同的植株。经测交、回交、姐妹交的后代育性分离调查, 不育株与可育株呈1︰1分离, 以不育株为母本与普通品种配制杂交组合, 其后代育性呈1︰1分离, 可育株后代分离不出不育株, 表明S221不育性受核内1对显性不育基因控制。     

长穗颈温敏核不育水稻双低培eS遗传特性的研究

双低培eS是由双低S通过辐射诱变选育出的长穗颈温敏核不育水稻，其穗颈伸出长度比双低S增长17 cm。用双低培eS与9311杂交，F1表现为正常半矮秆，但比培矮64S/9311（两优培九）穗颈伸出长度增加2.7 cm，且不包颈。从F2群体中分离出的正常半矮秆与长穗颈高秆比例经χ2测验符合3∶1分离规律，说明该突变的长穗颈性状为一对隐性基     

Genetic analysis of mesocotyl length and its relationship with other agronomic characters in rice (Oryza sativa L.)

Summary Mesocotyl length is an important character in promoting seedling emergence of direct-seeded rice. Genetic analysis of rice mesocotyl length was conducted using a six parent diallel cross. Generation mean analysis was carried out on parents (P), F1, F2 and backcrosses (B) of three crosses to complement the genetic information from the diallel analysis. Both analyses demonstrated the presence of significant additive and dominance effects. Duplicate type of non-allelic interaction was detected by the generation mean analysis and two crosses showed significant negative dominance gene effect. Dominance was partial and the narrow sense heritability estimate for mesocotyl length was high, indicating the preponderance of the additive effects.Mesocotyl length was negatively but weakly correlated with the coleoptile length and length of the second internode L2. There was no correlation between mesocotyl length and other mature plant characters such as plant height and internode lengths L₁, (L₁ being the peduncle with subsequent internodes to the base of the plant). Selection for mesocotyl length can therefore be carried out independent of these plant characters and semidwarf rice varieties with long mesocotyl can be developed.