Efficient tissue culture and regeneration methods were established using immature wheat embryos as expiants. Genotype differences in culturability were evident, and from the ten accessions most amenable to culture, a total of 2,846 plants were regenerated. Extensive somaclonal variation for morphological and biochemical traits was observed among 142 regenerants of a Mexican breeding line, 'Yaqui 50E', and their progeny. Variant characters included height, awns, tiller number, grain colour, heading date, waxiness, glume colour, gliadin proteins and α-amylase regulation. The variant characters were heritable through two seed generations and included traits under both simple and quantitative genetic control. Segregation data suggested that mutations both from dominance to recessiveness, and from recessiveness to dominance, had occurred. Most mutations in the primary regenerants were in the heterozygous state but some were true-breeding and presumed to be homozygous. Chromosome loss or addition did not account for the variation and none of the variant phenotypes was observed in over 400 plants from the parental seed source. The distinctive parental gliadin pattern was maintained in the somaclones thus excluding seed contamination or cross-pollination as a source of the variation.

The objectives of this study were to select and initially characterize mutants of soybean (Gleine max L. Meff. cv Williams) with decreased ability to reduce nitrate. Selection involved a chlorate screen of approximately 12,000 seedlings (progeny of mutagenized seed) and subsequent analyses for low nitrate reductase (LNR) activity. Three lines, designated LNR-2, LNR-3, and LNR-4, were selected by this procedure.In growth chamber studies, the fully expanded first trifoliolate leaf from N03-grown LNR-2, LNR-3, and LNR-4 plants had approximately 50% of the wild-type NR activity. Leaves from urea-grown LNR-2, LNR-3, and LNR4 plants had no NR activity while leaves from comparable wild-type plants had considerable activity, the latter activity does not require the presence of NOs-in the nutrient solution for induction and on this basis is tentatively considered as a constitutive enzyme. Summation of constitutive (urea-grown wild-type plants) and inducible (N03-grown LNR-2, LNR-3, or LNR-4 plants) leaf NR activities approximated activity in leaves of NO3--grown wild-type plants. Root -(17, 25). Chlorate also competes with N03 for uptake in Hordeum vulgare and Arabidopsis thaliana roots (5, 6). Thus, C103-can act as an analog of NO3 during uptake, as well as during reduction by NR. The analog characteristic of C103 and the resultant toxicity symptoms associated with C103-reduction suggested that this ion could be used as a screening agent to identify organisms with decreased N03 uptake and metabolism. Although mechanisms of C103 toxicity other than that involving NR are possible (14,19,27), Cl03 resistant mutants which are NR deficient have been found in higher plants (7, 22,26) and plant cell lines (14,18,19). Soybeans (Glycine max L. Merr.) have been shown to display characteristic C103 toxicity symptoms (browning and stunting of leaves) (9, 28), and this was the basis for using a C103 screen to identify plants defective in N03 metabolism. This paper reports on the selection, from progeny of mutagenized seed, and initial characterization of three soybean lines which have decreased leaf NR activity compared with wild-type plants. MATERIALS AND METHODS

A total of 256 selected lines derived from tissue culture of three hexaploid wheat cultivars were grown in a replicated hill plot experiment to examine somaclonal variation in agronomic characters. The lines were derived by single plant selection for various characters from a total of 100 regenerants, and were either SC3 or SC4 generation in the test. Significant variation was found in all the characters measured: height, grain number per spike, kernel weight, yield, total dry weight and harvest index. In most cases, variation could be identified which was both less than and greater than the parental controls. However, there was also an apparent effect of the parent cultivar on the total amount and direction of the variation. For two cultivars, lines could be traced back through the culture phase to individual explant embryos. Many of the original embryos contributed significant variation, and most characters showed significant variation arising from more than one embryo. In the following year, 32 lines selected from the hill plot experiment were grown in larger replicated plots and yield, harvest index and a number of grain and baking quality characters were measured. No lines selected for high yield or harvest index maintained significant improvements over their parental controls. However, significant variation was displayed for many of the quality characters examined. Significant increases in kernel weight, hardness and protein content, and a significant reduction in yellow pigmentation represented potentially useful improvements. Only unfavourable variation was seen in flour yield and in mixograph height, time and breakdown.

1989. From somatic variation to variant plants: mechanisms and applications. Genome,. Plants from cell cultures show a high incidence of mutation. The causes of somaclonal variation are unknown, but the genetic consequences have been analysed. A range of genetic events are responsible, including single base changes; altered gene copy number; altered expression of multigene families; chromosome fragment interchanges; and mobilisation of transposable elements. Recent applications of these phenomena are discussed in this paper, for example, in vitro selection, somaclonal variation for agronomic traits, and limited gene transfer from cultured sexual and somatic hybrids. Research is outlined attempting to use high frequency chromosomal interchanges in wheat cell cultures to introgress genes from alien chromosomes. Two examples are cereal cyst nematode resistance on a rye chromosome and barley yellow dwarf resistance on a Thinopyrum chromosome. Some presumptive introgressed lines show selfed and backcross segregations, suggesting that the resistance, but not other alien markers, is now on a wheat chromosome. From somatic variation to variant plants: mechanisms and applications. Genome, 31 : 705-711. Les plantes issues de cultures de cellules montrent une incidence ClevCe de mutations. Les causes des variations somaclonales sont inconnues, mais les consCquences gCnktiques ont Ct C analyskes. Une garnrne d'Cvknements gknktiques en est responsable et comporte : des changements portant sur une seule base, un nombre modifiC de copies de gbnes, une expression modifiCe de familles plurigkniques, des Cchanges de fragments de chromosomes, ainsi que la mobilisation d'C1Cments transposables. Des applications rCcentes de ces phCnombnes sont ici discutCs; par exemple, la vitrosClection, la variation somaclonale en regard de traits agronomiques, le transfert limit6 de gknes chez les hybrides somatiques et les hybrides sexuks mis en culture. Des recherches ont kt6 planifiCes visant ?i utiliser les frCquences ClevCes d'Cchanges chromosomiques qui surviennent dans les cultures de cellules de blk, en vue de favoriser l'introgression de gknes de chromosomes Ctrangers; voici deux exemples : la rksistance sur un chromosome du seigle ?i la formation de kystes racinaires chez les cCrCales causCs par les nkmatodes et la rCsistance sur un chromosome de Thinopyrum du dCveloppement du nanisme jaune chez l'orgre. Certaines lignCes, prCsumCment introgresskes, prCsentent des sCgrCgations d'auto-et de rktrocroisement qui suggkrent que la rCsistance est prksentement localisCe sur un chromosome du blC, mais non les autres marqueurs Ctrangers.

No abstract

The progeny of 149 plants regenerated from tissue culture of immature wheat (Triticum aestivum) embryos were screened for variation in their grain β-amylase isozyme pattern. One regenerant was found which was heterozygous for a variant pattern characterized by the presence of at least five new isozyme bands, as well as an increased intensity in existing bands in two more positions. The F2 of a homozygous variant crossed back to the parent segregated in an approximate 3∶1 ratio but resolution of the gels was not sufficient to distinguish whether this represents a dominant or co-dominant single mutant gene. No chromosome abnormalities were evident in mitosis or meiosis of the homozygous variant or in the F1 of the variant crossed back to the parent. No recombination has been seen between the variant bands and production of multiple bands from a single locus is consistent with the nature of the known β-amylase loci. However, the variant bands were not evident in a survey of 111 diverse genotypes, nor were they present in developing grain of the parent cultivar. Therefore, this variant could represent a rare mutation leading to expression of a currently unexpressed locus.

Community-based natural resource management (CBNRM) has grown in stature as a key component of many national natural resource and rural development governance systems. Despite their growth, the integrity of CBNRM governance systems has rarely been analysed in a national context. To enhance dialogue about how best to design and deploy such systems nationally, this paper analyses the Australian system in detail. The Australian system was selected because the nation has a globally recognised and strong history of CBNRM approaches. We first contextualise the international emergence of national CBRM governance systems before analysing the Australian system. We find that a theoretically informed approach recognising regions as the anchors in brokering multi-scale CBNRM was applied between 2000 and 2007. Subsequent policy, while strengthening indigenous roles, has tended to weaken regional brokering, Commonwealth–state cooperation and research collaboration. Our findings and consequent emerging lessons can inform Australian policy makers and other nations looking to establish (or to reform existing) CBNRM governance systems. Equally, the research approach taken represents the application of an emerging new theoretical framework for analysing complex governance systems.

The progeny of 551 regenerants of the hexaploid wheat cultivar 'Millewa' were analysed for somaclonal mutants at the threeAdh-1 loci in hexaploid wheat. Seventeen regenerants gave rise to progeny having altered ADH1 zymograms. Progeny with altered zymograms in 13 of these regenerants were aneuploid. The remaining 4 regenerants gave rise to euploid progeny with altered ADH1 zymograms. The genetics of three of these somaclonal mutants is described in detail. These regenerants were interpreted to possess a 4Aα isochromosome, a 3BS/4Aα translocation and a 7BS/4Aα translocation, respectively.