Mango Breeding Support

The Mango Breeding Support project provided technical, research and development support to the Queensland-based, Australian Mango Breeding Program to develop and evaluate breeding systems and technologies that improve mango breeding efficiency. Adoption of efficient breeding support technologies will allow breeders to identify genes for desirable plant and fruit traits in parent varieties and incorporate those genes into new hybrid varieties more efficiently and rapidly. The project compared traditional hand pollination methods with DNA marker assisted selection (MAS) open-pollinated methods to identify paternity and found both systems had advantages. Marker assisted paternity identification was not practical in all cases and relied on a greater range of technical skills and resources being available to the breeder. It is expected that MAS will become even more efficient when markers are available for production and quality traits in addition to parental identification. Breeding for anthracnose resistance in mango is in its infancy. This project has identified several accessions in related Mangifera species with potential tolerance to postharvest anthracnose and tested the compatibility of these related species with the common mango and if the tolerance is transferable. The project investigated ways of determining a trees postharvest fruit disease resistance status in seedlings to avoid the up to 6 year wait for trees to crop. Identification of genes and gene markers for plant development, stress response, fruit colour and flavour development was another goal of this project. Twenty five new expressed sequence tag (EST) derived single sequence repeat (SSR) DNA markers were identified and tested across a diverse range of germplasm. These markers were shown to be useful in determining genetic relationships, exploring potential pedigrees and estimating the genetic background of cultivated accessions of M. indica. They are the first reported EST-SSR markers suitable to cross-amplify in five wild Mangifera species. The technologies that have been shown to be more efficient have been incorporated in to the Australian Mango Breeding Project. Other technologies being researched that are not yet fully developed to the stage where they can be adopted in a working breeding program are being progressed in other related research projects

Infrared astronomy

The decade of 1990's presents an opportunity to address fundamental astrophysical issues through observations at IR wavelengths made possible by technological and scientific advances during the last decade. The major elements of recommended program are: the Space Infrared Telescope Facility (SIRTF), the Stratospheric Observatory For Infrared Astronomy (SOFIA) and the IR Optimized 8-m Telescope (IRO), a detector and instrumentation program, the SubMilliMeter Mission (SMMM), the 2 Microns All Sky Survey (2MASS), a sound infrastructure, and technology development programs. Also presented are: perspective, science opportunities, technical overview, project recommendations, future directions, and infrastructure

Mango germplasm screening for the identification of sources of tolerance to anthracnose

Colletotrichum species are one of the most common causes of postharvest fruit rot in mango in Australia, particularly in the tropical region of north Queensland, and can result in significant losses if not managed. The research aims were to identify sources of anthracnose tolerance and to determine if host material other than fruit could improve or fast track the screening process and result in improved breeding efficiency. Access to the Australian National Mango Genebank (ANMG) collection enabled fruit screening of more than 100 Mangifera indica cultivars or Mangifera species for tolerance to anthracnose by artificial inoculation with Colletotrichum asianum over a period of 14 years. Mean lesion diameters were compared with those on a known susceptible M. indica cultivar Kensington Pride (KP) and a tolerant M. laurina cultivar Lombok. Inoculation of leaf discs and entire leaves was evaluated in the laboratory and the field as alternative assays for tolerance to anthracnose and was assessed by presence/absence of disease. Screening of fruit has shown that anthracnose tolerance within the mango germplasm is highly variable and needs to be assessed over multiple years. None of the alternative laboratory bioassays provided consistent or reliable data. The in-field artificial inoculation of immature leaf flush was successful but was not deemed suitable for adoption due to practical restraints. While resistance to anthracnose in fruit has not yet been identified, some cultivars and Mangifera spp. showed promise for inclusion as parents in future breeding programs

OB Stars & Stellar Bowshocks in Cygnus-X: A Novel Laboratory Estimating Stellar Mass Loss Rates

We use mid-IR images from the Spitzer Cygnus~X Legacy Survey to search for stellar bowshocks, a signature of early type "runaway" stars with high space velocities. We identify ten arc-shaped nebulae containing centrally located stars as candidate bowshocks. New spectroscopic observations of five stars show that all are late O to early B dwarfs. Our morphologically selected sample of bowshock candidates encompasses diverse physical phenomena. Three of the stars appear to be pre-main-sequence objects on the basis of rising SEDs in the mid-IR, and their nebulae may be photon-dominated regions (PDRs). Four objects have ambiguous classification. These may be partial dust shells or bubbles. We conclude that three of the objects are probable bowshocks, based on their morphological similarity to analytic prescriptions. Their nebular morphologies reveal no systematic pattern of orientations that might indicate either a population of stars ejected from or large-scale hydrodynamic outflows from Cyg OB2. The fraction of runaways among OB stars near Cyg OB2 identified either by radial velocity or bowshock techniques is ~0.5%, much smaller than the 8% estimated among field OB stars. We also obtained a heliocentric radial velocity for the previously known bowshock star, BD+43\degr3654, of -66.2+/-9.4 km/s, solidifying its runaway status and implying a space velocity of 77+/-10 km/s. We use the principles of momentum-driven bowshocks to arrive at a novel method for estimating stellar mass loss rates. Derived mass loss rates range between 10^-7 and few x10^-6 solar masses/yr for the three O5V -- ~B2V stars identified as generating bowshocks. These values are at the upper range of, but broadly consistent with, estimates from other methods. (Abridged)Comment: 49 pages, 19 figures; Accepted for publication in ApJ; full-resolution color figure version available at http://physics.uwyo.edu/~chip/Papers/CygXBowshocks; comments invite