Genetic diversity of carotenoid-rich bananas evaluated by Diversity Arrays Technology (DArT)

The aim of this work was to evaluate the carotenoid content and genetic variability of banana accessions from the Musa germplasm collection held at Embrapa Cassava and Tropical Fruits, Brazil. Forty-two samples were analyzed, including 21 diploids, 19 triploids and two tetraploids. The carotenoid content was analyzed spectrophotometrically and genetic variability was estimated using 653 DArT markers. The average carotenoid content was 4.73 μg.g -1 , and ranged from 1.06 μg.g -1 for the triploid Nanica (Cavendish group) to 19.24 μg.g -1 for the triploid Saney. The diploids Modok Gier and NBA-14 and the triploid Saney had a carotenoid content that was, respectively, 7-fold, 6-fold and 9-fold greater than that of cultivars from the Cavendish group (2.19 μg.g -1). The mean similarity among the 42 accessions was 0.63 (range: 0.24 to 1.00). DArT analysis revealed extensive genetic variability in accessions from the Embrapa Musa germplasm bank

Validation of quantitative trait loci for aluminum tolerance in Chinese wheat landrace FSW

Citation: Dai, J., Bai, G., Zhang, D. et al. Euphytica (2013) 192: 171. https://doi.org/10.1007/s10681-012-0807-9Aluminum (Al) toxicity is one of the major constraints for wheat production in acidic soils worldwide and use of Al-tolerant cultivars is one of the most effective approaches to reduce Al damage in the acidic soils. A Chinese landrace, FSW, shows a high level of tolerance to Al toxicity and a mapping population of recombinant inbred lines (RILs) was developed from a cross between FSW and Al-sensitive US spring wheat cultivar Wheaton to validate the quantitative trait loci (QTL) previously identified in FSW. The mapping population was evaluated for net root growth (NRG) during Al stress in a nutrient solution culture and hematoxylin staining score (HSS) of root tips after Al stress. After 132 simple sequence repeat (SSR) markers from three chromosomes that were previously reported to have the QTLs were analyzed in the population, two QTLs for Al tolerance from FSW were confirmed. The major QTL on chromosome 4DL co-segregated with the Al-activated malate transporter gene (ALMT1), however, sequence analysis of the promoter region (Ups4) of ALMT1 gene indicated that FSW contained a marker allele that is different from the one that was reported to condition Al tolerance in the Brazilian source. Another QTL on chromosome 3BL showed a minor effect on Al tolerance in the population. The two QTLs accounted for about 74.9% of the phenotypic variation for HSS and 72.1% for NRG and demonstrated an epistatic effect for both HSS and NRG. SSR markers closely linked to the QTLs have potential to be used for marker-assisted selection (MAS) to improve Al tolerance in wheat breeding programs

Recent advances in rapid and sensitive screening for abiotic stress tolerance

Traditionally, screening for abiotic stress tolerance at field level was based on necrosis scores and shoot biomass reduction on stress exposure, relative to unstressed controls. However, such a measure of tolerance screening is laborious, destructive, and time consuming, and results are subjected to environmental variation. Recently, noninvasive, high-throughput screening techniques have been developed for screening abiotic stress tolerance in crops. In this direction, some physiological, biochemical, and/or molecular indicators/markers have been identified for rapid and sensitive indirect screening of germplasm. Physiological markers like membrane damage based on electrolyte leakage, stomatal conductance, chlorophyll content and so on are currently available. In addition, quick and sensitive screening in crop plants is possible with biochemical markers like status of reactive oxygen species and oxidative damage to biological macromolecules like lipids, proteins, and nucleic acids. Identification of molecular markers associated with the tolerance response has also made rapid and sensitive indirect selection possible in a few crop species. Thus, development of such methods is valuable in breeding for abiotic stress tolerance in plants

Exploring wheat landraces for rust resistance using a single marker scan

Marker-trait associations identified in diverse germplasm can be exploited in crop improvement programs. An attempt to establish such associations was made by evaluating 205 wheat landraces for stripe rust, leaf rust and stem rust responses in the field over three crop seasons. Diversity arrays technology was used to genotype the landraces and associations were identified using a single-marker scan. Sixty-eight markers were significantly associated with rust resistance. Several significantly associated loci coincided with the presence of known major genes or QTL for rust resistance. In contrast, many marker-rust response associations identified in this analysis for each of the three rust diseases uncovered new loci. Dual associations; stripe rust-leaf rust (1AL, 2BS, 2BL, 3DL, 5BS, 6BS and 7DL), leaf rust-stem rust (5BL) and stripe rust-stem rust (4BL and 6AS) resistance were also observed. These associations could enable a cost-effective targeted mapping of dual rust resistance. Some marker-trait associations identified in this study have been validated through genetic analyses and formal naming of resistance loci