Genetical Studies on the Mode of Inheritance and Localization of the amo1 (High Amylose) Gene in Barley

In the high amylose starch mutant ‘Glacier AC38’, a single recessive gene designated amo1 is responsible for an amylose content of up to 45%. A rapid technique was established in order to evaluate the amylose/amylopectin ratio in half kernels. To localize this gene, crosses with multiple marker lines and trisormes were conducted. In addition, RFLP markers were used to determine their mapping distance to amo1. Two markers are located 2 cM and 7 cM, respectively, from amo1 on chromosome 5S (1HS). The relationship between the wx and amo1 genes was also examined and the role of the amo1 gene in starch synthesis is discussed.     

Gibberellins as gametocides for the common onion (Allium cepa L.). III. GA4+7 and pollen viability

Summary The gametocidal effect of GA₄₊₇ in onion is strong in respect of pollen production but very weak or absent in respect of pollen viability. Large scale application of GA₄₊₇ for the production of onion hybrid seed is still impossible because of low seed yield and high costsof required chemicals. On a small scale, however. GA₄₊₇ can be used very well to emasculate breeding material.Because of switching over to the gibberellin terminology of plant physiologists, this title slightly deviates from that of the two previous articles.     

棉花质核不育材料晋A的发现与观察

发现并系统观察了棉花雄性不育材料晋Ａ。通过镜检、自交、测交、回交、开放授粉和网罩试验表明，此材料不育性完全而稳定，陆地棉品种可作其完全保持系，海岛棉品种可使其育性恢复，是我国新发现的又一质核不育材料。其不育胞质来自陆地棉，但与其它胞质系不同，这一发现为棉花三系配套、实现产量上的突破提供了新的胞质基因源。     

Utilization of deletions to localize a gene for resistance to the cereal cyst nematode, Heterodera avenue, on an Aegilops ventricosa chromosome

A previous RFLP analysis showed that the Aegilops ventricosa chromosome 6M^V which compensates for the absence of 6D in 6M^V (6D) wheat substitution lines was a 2/6 translocated chromosome, either 2S–6S.6L or 2S–6L.6S. The distal part of its long arm consists of a translocated segment belonging to homoeologous group 2. Chromosome 6M^V carries a gene(s) for resistance to cereal cyst nematode. In order to define the part of 6M^V (2S or 6S or 6L) involved in this resistance, addition lines with a 6M^V deleted either for its short arm or for the distal part of its long arm were evaluated. It was shown that the gene(s) is carried by the group 2 translocated segment. The hypothesis that the gene(s) could be allelic to Cre2, another gene conferring resistance to the nematode introduced into the wheat complement from Ae. ventricosa is discussed.     

Potential use of doubled haploid lines for the screening of resistance to yellow rust (Puccinia striiformis) in hexaploid wheat

Doubled haploid lines derived from anther culture of two Iranian spring wheat genotypes‘Ghods’susceptible and‘9106’resistant to yellow rust in Iranian field conditions, and their F₁ hybrids were used in this study. Seedlings of 36 doubled haploid lines, selected out of 96 according to their agronomic traits and the two parental genotypes were inoculated with eight races of yellow rust. The parental genotypes (‘Ghods’and‘9106’) were segregating for some of the races but their doubled haploid lines were either resistant or susceptible to them.‘Ghods’was susceptible to three of the races studied but three doubled haploid lines derived from it were resistant to them. Five selected doubled haploids from the‘9106’genotype and six from F₁ hybrid plants were resistant to all eight races tested. After further investigations in Iranian field conditions it was found that some of these lines can be used as donor genotypes for resistance to yellow rust in wheat breeding programmes. Use of these genotypes should be possible if the French yellow rust races used for selection also represent the dominant races in Iran. It can be concluded that anther culture provides an efficient method for fixing genes of resistance to yellow rust and desirable doubled haploids from F₁ plants can be derived.     

秋水仙素和二甲基亚砜诱导矮败小麦孤雌生殖的效应

在隔离区内，以矮败小麦轮回选择群体中的不育株为供试亲本，用秋水仙素（Ｃｏｌ）和二甲基亚砜（ＤＭＳＯ）诱导孤雌生殖。结果表明，Ｃｏｌ和ＤＭＳＯ均具有诱导不育株孤雌生殖的作用，并且二者之间存在极显著的互作效应。同一药剂不同的诱导方法，其诱导效果有差异；小穗剪颖处理的孤雌生殖结实率较高；处理时间和套袋与否对孤雌生殖结实率影响不显著。孤雌生殖纯系在纯度和遗传稳定性方面均接近于对照品种（丰抗８号）。从遗传理论和育种实践的角度，讨论了药物诱导矮败小麦孤雌生殖的可行性及在小麦育种中的应用价值     

Effects of homoeologous group 1 and 6 chromosomes of the Cappelle-Desprez (Bezostaya 1) substitution lines on aspects of bread-making quality of wheat

Summary The group 1 and 6 inter-varietal chromosome substitution lines of Cappelle-Desprez (Bezostaya 1) were intercrossed along with the donor and recipient varieties, Cappelle-Desprez and Bezostaya 1, to give 36 genetically different families. The analysis of the means of these families showed that variation in SDS-sedimentation volume fitted a predominantly additive model. There were no significant within or between chromosome interactions among the group 1 and 6 chromosomes. Nor was there any evidence for interactions between these chromosomes and those of the background. Significant dominance/within chromosome interactions amongst the background chromosomes were however detected. Some of the positive effects on SDS-sedimentation were associated with increased grain hardness. Chromosome effects on % grain protein were not correlated with SDS-sedimentation.     

K—19型小麦雄性不育系的创建及其育性恢复源的发现

以粘果山羊草Ａｅ．１９（Ａｅ．ｋｏｔｓｃｈｙｉ，１９）为母本，中国春和云南铁壳小麦为桥梁亲本，进行远缘杂交，获得雄性不育株。再用普通麦７８－１等为轮回亲本，与其测交并连续回交，育成了Ｋ－１９－７８－１Ａ等小麦雄性不育系。然后用５００余份普通小麦品种（系）与Ｋ－１９－７８－１Ａ进行测交，获得４６９个组合Ｆ１杂种，其中７３个测交种（占总数的１５．５７％）能完全保持Ｋ－１９型小麦的雄性不育性。其余３９６个测交种（占总数的８４．４３％）对Ｋ－１９型小麦雄性不育系表现不同程度的育性恢复。恢复度幅度为１．０％～９７．５％。３９６份材料中有１４．１４％对Ｋ－１９型不育系表现高度恢复，按国内法计算恢复度达到８０．１％～９７．５％；测交、回交后代产生单倍体频率在０～１７．５％之间，发现一批综合性状好、不产生单倍体的保持系和恢复源。     

Resistance to barley yellow-dwarf-virus disease in derivatives of crosses between hexaploid wheat and species of Lophopyrum (Triticeae; Poaceae)

Among the wheatgrasses that are possible sources of genetic resistance for wheat to barley yellow-dwarf-virus disease (BYD) are those that have been commonly subsumed under the name Agropyron elongatum (Host) P. Beauv. Two of these wheatgrass species are the diploid Lophopymm elongatum (Host) Á. Löve (2n = 2x = 14) and the decaploid L. ponticum (Podp.) Á. Löve (2n = 10x = 70). These two species, the addition and substitution lines of L. elongatum chromosomes in hexaploid wheat (Triticum aestivum L.), and derivatives of hybrids between hexaploid wheat and L. ponticum, were screened for resistance to BYD, as defined by visual symptoms in field-grown plants. The two species, an amphiploid derived from L. elongatumבChinese Spring’ wheat, and the derivatives involving L. ponticum chromosomes were all highly resistant. The substitution and addition lines of L. elongatum chromosomes in ‘Chinese Spring’ revealed that the genetic control of resistance in L. elongatum must be complex, with more than one critical locus involved. Chromosomes 2E and 5E are involved and there are lesser contributions to resistance from the remaining wheatgrass chromosomes. One highly resistant derivative was determined to have only three pairs of L. ponticum chromosomes. It has a wheat-like morphology and shows promise for further characterization.     

Doubled-haploid versus single-seed descent and S1-family variation for testcross performance in a maize population

Progress made in the in situ gynogenesis technique since 1990 now allows production of a high number of maize (Zea mays L.) doubled-haploid (DH) lines. The aim of the study was to compare DH lines versus selfing lines for testcross performance. DH and single-seed descent (SSD) lines were produced from random S₁ progenies of a broad-base population. For grain yield, kernel moisture, plant height, ear height and leaf length, the three population means were similar. Except for kernel moisture, the genetic variance of DH lines was nearly twice as high as the genetic variance of S₁ families, as expected. On the other hand, genetic variance among SSD lines was only 1.5 times higher than the genetic variance of S₁ families. This lower variance could be due to a selection bias in the method of production of SSD lines. However, for all traits, heritability of SSD or DH lines was higher than heritability of S₁ families. Epistasis effects in DH progenies were not significant. The consequence was a high correlation between S₁ testcross progenies and DH or SSD testcross progenies, meaning that the S₁ testcross value can be used to select the best families from which DH lines will be extracted. As a whole, the observed variation in DH lines appeared to be more in accordance with the observed variation among S₁ families than with the observed variation among SSD lines.