Tropical peach breeding and evaluation

Breeding new peach and nectarine cultivars that are adapted to tropical climates and produce fruit of high quality.

Macadamia Breeding and Conservation

DEEDI is tendering for this project because it considers that macadamia breeding is essential for long-term industry viability and that new productive cultivars will be the basis for the industry to withstand future competition from overseas and from other nut crops.

Improvement and Maintenance of Turf Demonstration Plots

DEEDI have built and maintained a living library of turf grass selections of 138 different turf cultivars. Material is also preserved in tubs in a protected growing environment. The maintenance and ongoing upgrading of these plots requires significant resources to maintain their integrity. As the plots have been in place since 2000, they are currently in need of significant repair. This project will assist in the improvement and maintenance of the turf library for the benefit of the turf industry producers and Australian turf research more generally.

Macadamia Regional Variety Trials Series 3 - Phase 2

Regional variety trials (RVT) established in 1983 and again in 1997 identified superior varieties for the macadamia industry. From the 1983 trials, guidelines were developed to assist growers to select the most appropriate new varieties for their particular orchards and many of these superior varieties have been enthusiastically adopted by industry. This is also being done for varieties in the 1997 trials. Many of the best cultivars have already been adopted by growers on the basis of annual reports of yield and quality. Industry development over the next 10 to 20 years will be largely dependent on new, superior varieties selected in these RVT5, including new selections from the macadamia industry breeding program.

The application of DArTseq technology to pineapple

DArTseq technology is potentially the most appropriate system to discover hundreds of polymorphic genomic loci, scoring thousands of unique genomic-wide DNA fragments in one single experiment, without requiring existing DNA sequence information. The DArT complexity reduction approach in combination with Illumina short read sequencing (Hiseq2000) was applied. To test the application of DArTseq technology in pineapple, a reference population of 13 Ananas genotypes from primitive wild accessions to modern cultivars was used. In a comparison of 3 systems, the combination of restriction enzymes PstI and MseI performed the best producing 18,900 DArT markers and close to 20,000 SNPs. Based on these markers genetic relationships between the samples were identified and a dendrogram was generated. The topography of the tree corresponds with our understanding of the genetic relationships between the genotypes. Importantly, the replicated samples of all genotypes have a dissimilarity of close to 0.0 and occupy the same positions on the tree, confirming high reproducibility of the markers detected. Eventually it is planned that molecular markers will be identified that are associated with resistance to Phytophthora cinnamomi (Pc), the most economically important pathogen of pineapple in Australia, as genetic resistance is known to exist within the Ananas. Marker assisted selection can then be utilized in a pineapple breeding program to develop cultivars resistant to Pc.

Barley Grains Defects (Blackpoint, Pre-harvest sprouting, Kernal staining)

Screening new and existing breeding germplasm and cultivars for grain defect tolerance for breeding programs, evaluate new methods and technologies to screen more effectively for the barley grains defects - pre-harvest sprouting, blackpoint, kernel discolouration, and investigate genetic mechanisms involved in controlling barley grain defect tolerance.

DAQ00152 Herbicide Tolerance Screening in Northern Region (Phase IV)

The previous projects (phase I - III) highlighted that northern region wheat and barley cultivars differ considerably in their sensitivity to herbicides. The new project will focus on increased screening of advanced breeding lines and new cultivars lines to commonly used herbicides, for barley, chickpea and wheat. Studies on impact of environment on herbicide x genotype responses will also be undertaken with the national team. The new information will be added to the existing information package on herbicide tolerance. Thus, adverse impacts of herbicides on productivity in northern region will be reduced, as growers and agronomists will select safer herbicides for their sown variety, or select more tolerant varieties for their important herbicides.

Stay-green wheat for increased yield and yield stability

This project will provide information, germplasm, selection techniques and strategies for breeders to develop high-yielding stay-green wheat cultivars for Australian growers via a "three pronged" research strategy.

Tobacco Streak Virus in cotton-scoping study

In 2006, Tobacco streak virus (TSV) was identified as the causal agent of the devastating sunflower necrosis disease in central Queensland (CQ), and subsequently in 2007 as the cause of major losses in mungbeans in the same area. It has been a major factor in the recent downturn in the sunflower industry in CQ. Surveys in 2007/2008 as part of a one year scoping study (project 03DAQ005) found TSV in cotton in CQ. The symptoms were mostly confined to the feeding sites of the thrips and appeared as reddish spots and rings, but only occasionally the plants were systemically infected and showed a chlorotic mosaic and leaf deformation. The major objectives of this project (DAQ0002) were to determine: the incidence and distribution of TSV in cotton and its likely effect on yield; the thrips vector species associated with TSV infections in cotton; and the factors that may lead to systemic infections. In contrast to the extensive damage observed in sunflower and mungbean crops from the same region, TSV has caused no measurable damage in commercial cotton crops surveyed in CQ over the seasons 2008/9 to 2010/11. No TSV infected cotton was found in regions outside of CQ and the geographical distribution of TSV disease in cotton (and other susceptible hosts) appears to be closely related to the distribution of the major alternative host, parthenium weed. The most likely thrips species responsible for transmission of TSV into cotton is the tomato thrips (Frankliniella schultzei) and onion thrips (Thrips tabaci). Systemically infected plants are rarely seen in commercial crops and have also been rarely produced in controlled tests. It appears that systemic infection may be transient with only mild symptoms being produced intermittently. With current cultivars and conditions, it appears likely that TSV will continue to cause only minor levels of mild local lesions with no impact on yield in cotton crops. It appears that no specific control strategies are required to limit the impact of TSV in cotton. However, general farm hygiene to minimise the presence of the major alternative host of TSV, parthenium weed, is advised and may be of vital importance if TSV susceptible rotational crops such as mung beans are grown.

Isohydric and anisohydric characterisation of vegetable crops. The classification of vegetables by their physiological responses to water stress

Research on the physiological response of crop plants to drying soils and subsequent water stress has grouped plant behaviours as isohydric and anisohydric. Drying soil conditions, and hence declining soil and root water potentials, cause chemical signals—the most studied being abscisic acid (ABA)—and hydraulic signals to be transmitted to the leaf via xylem pathways. Researchers have attempted to allocate crops as isohydric or anisohydric. However, different cultivars within crops, and even the same cultivars grown in different environments/climates, can exhibit both response types. Nevertheless, understanding which behaviours predominate in which crops and circumstances may be beneficial. This paper describes different physiological water stress responses, attempts to classify vegetable crops according to reported water stress responses, and also discusses implications for irrigation decision-making.

Influence of soil organic amendments on suppression of the burrowing nematode, Radopholus similis, on the growth of bananas.

Radopholus similis is a major constraint to banana production in Australia and growers have relied on nematicides to manage production losses. The use of organic amendments is one method that may reduce the need for nematicides, but there is limited knowledge of the influence of organic amendments on endo-migratory nematodes, such as R. similis. Nine different amendments, namely, mill mud, mill ash, biosolids, municipal waste compost, banana residue, grass hay, legume hay, molasses and calcium silicate were applied to the three major soil types of the wet tropics region used for banana production. The nutrient content of the amendments was also determined. Banana plants were inoculated with R. similis and grown in the soil-amendment mix for 12-weeks in a glasshouse experiment. Assessments of plant growth, plant-parasitic nematodes and soil nematode community characteristics were made at the termination of the experiment. Significant suppression of plant-parasitic nematodes occurred in soils amended with legume hay, grass hay, banana residue and mill mud relative to untreated soil. These amendments were found to have the highest N and C content. The application of banana residue and mill mud significantly increased shoot dry weight at the termination of the experiment relative to untreated soil. Furthermore, the applications of banana residue, grass hay, mill mud and municipal waste compost increased the potential for suppression of plant-parasitic nematodes through antagonistic activity. The application of amendments that are high in C and N appeared to be able to induce suppression of plant-parasitic nematodes in bananas, by developing a more favourable environment for antagonistic organisms.

Mile-a-minute (Mikania micrantha): its distribution, growth and physical and socio-economic impacts in Papua New Guinea

Mikania micrantha, Kunth. H.B.K (Asteraceae) or mile-a-minute is a weed of Neotropical origin in 17 Pacific Island countries. It is becoming increasingly regarded as an invasive weed in Papua New Guinea and is now the focus of an Australian Government-funded biological control program. As part of the program, growth rates, distribution and physical and socia-economic impacts were studied to obtain baseline data and to assist with the field release of biological control agents. Through public awareness campaigns and dedicated surveys, mikania has been reported in most lowland provinces. It is particularly widespread in East New Britain and West New Britain Province. In field trials, mikania grew more than 1 metre per month in open sunny areas but slightly slower when growing under cocoa. The weed invades a wide range of land types, impacting on plantations and food gardens, smothering pawpaw, young cocoa, banana, taro, young oil palms and ornamental plants. In socia-economic surveys, mikania was found to have severe impacts on crop production and income generated through reduced yields and high weeding costs. These studies suggest that there would be substantial benefits to the community if biological control of mikania is successful.

Rain Damage to Strawberries Grown in Southeast Queensland: Evaluation and Genetic Control.

In Queensland, Australia, strawberries (Fragaria xananassa Duchesne) are grown in open fields and rainfall events can damage fruit. Cultivars that are resistant to rain damage may reduce losses and lower risk for the growers. However, little is known about the genetic control of resistance and in a subtropical climate, unpredictable rainfall events hamper evaluation. Rain damage was evaluated on seedling and clonal trials of one breeding population comprising 645 seedling genotypes and 94 clones and on a second clonal population comprising 46 clones from an earlier crossing to make preliminary estimates of heritability. The incidence of field damage from rainfall and damage after laboratory soaking was evaluated to determine if this soaking method could be used to evaluate resistance to rain damage. Narrow-sense heritability of resistance to rain damage calculated for seedlings was low (0.21 +/- 0.15) and not significantly different from zero; however, broad-sense heritability estimates were moderate in both seedlings (0.49 +/- 0.16) and clones (0.45 +/- 0.08) from the first population and similar in clones (0.56 +/- 0.21) from the second population. Immersion of fruit in deionized water produced symptoms consistent with rain damage in the field. Lengthening the duration of soaking of 'Festival' fruit in deionized water exponentially increased the proportion of damage to fruit ranging in ripeness from immature to ripe during the first 6-h period of soaking. When eight genotypes were evaluated, the proportion of sound fruit after soaking in deionized water in the laboratory for up to 5 h was linearly related (r(2) = 0.90) to the proportion of sound fruit in the field after 89 mm of rain. The proportion of sound fruit of the breeding genotype '2008-208' and 'Festival' under soaking (0.67, 0.60) and field (0.52, 0.43) evaluations, respectively, is about the same and these genotypes may be useful sources of resistance to rain damage.

DNA markers linked to the R(2) rust resistance gene in sunflower (Helianthus annuus L.) facilitate anticipatory breeding for this disease variant.

Pre-emptive breeding for host disease resistance is an effective strategy for combating and managing devastating incursions of plant pathogens. Comprehensive, long-term studies have revealed that virulence to the R (2) sunflower (Helianthus annuus L.) rust resistance gene in the line MC29 does not exist in the Australian rust (Puccinia helianthi) population. We report in this study the identification of molecular markers linked to this gene. The three simple sequence repeat (SSR) markers ORS795, ORS882, and ORS938 were linked in coupling to the gene, while the SSR marker ORS333 was linked in repulsion. Reliable selection for homozygous-resistant individuals was efficient when the three markers, ORS795, ORS882, and ORS333, were used in combination. Phenotyping for this resistance gene is not possible in Australia without introducing a quarantinable race of the pathogen. Therefore, the availability of reliable and heritable DNA-based markers will enable the efficient deployment of this gene, permitting a more effective strategy for generating sustainable commercial cultivars containing this rust resistance gene.

Review of genetic improvement of pineapple.

World consumption of fresh pineapple has quadrupled in less than 15 years (Loeillet and Pacqui, 2009). This phenomenal event started around 1996 when the first dedicated fresh market pineapple, '73-114', was released by Del Monte Inc. This was the culmination of somewhere in the vicinity of 34 years of breeding and selection and comprised 24 individual parent combinations (Anon., PRI breeding records). This demonstrates the difficulty of breeding new pineapple cultivars but also the value of a successful program. The success of '73-114' and the competitive nature of world pineapple markets have provided impetus for pineapple breeding programs. However, the highly heterozygous nature and self-incompatibility of pineapple limit breeding strategy options. This review looks at the collective experience in pineapple genetic improvement both conventional and using biotechnology tools, with an emphasis on fresh market pineapple. It focus on relevant pineapple reproductive biology, breeding strategies, parent cultivars and the relevance of biotechnology.