Sorghum bicolor
(L.) Moench is a multipurpose food crop which is ranked among the top five cereal crops in the world, and is used as a source of food, fodder, feed, and fuel. The genus
Sorghum
...consists of 24 diverse species. Cultivated sorghum was derived from the wild progenitor
S. bicolor
subsp.
verticilliflorum
, which is commonly distributed in Africa. Archeological evidence has identified regions in Sudan, Ethiopia, and West Africa as centers of origin of sorghum, with evidence for more than one domestication event. The taxonomy of the genus is not fully resolved, with alternative classifications that should be resolved by further molecular analysis. Sorghum can withstand severe droughts which makes it suitable to grow in regions where other major crops cannot be grown. Wild relatives of many crops have played significant roles as genetic resources for crop improvement. Although there have been many studies of domesticated sorghum, few studies have reported on its wild relatives. In
Sorghum
, some species are widely distributed while others are very restricted. Of the 17 native sorghum species found in Australia, none have been cultivated. Isolation of these wild species from domesticated crops makes them a highly valuable system for studying the evolution of adaptive traits such as biotic and abiotic stress tolerance. The diversity of the genus
Sorghum
has probably arisen as a result of the extensive variability of the habitats over which they are distributed. The wild gene pool of sorghum may, therefore, harbor many useful genes for abiotic and biotic stress tolerance. While there are many examples of successful examples of introgression of novel alleles from the wild relatives of other species from Poaceae, such as rice, wheat, maize, and sugarcane, studies of introgression from wild sorghum are limited. An improved understanding of wild sorghums will better allow us to exploit this previously underutilized gene pool for the production of more resilient crops.
Genetically diverse plant germplasm stored in ex-situ genebanks are excellent resources for breeding new high yielding and sustainable crop varieties to ensure future food security. Novel alleles ...have been discovered through routine genebank activities such as seed regeneration and characterization, with subsequent utilization providing significant genetic gains and improvements for the selection of favorable traits, including yield, biotic, and abiotic resistance. Although some genebanks have implemented cost-effective genotyping technologies through advances in DNA technology, the adoption of modern phenotyping is lagging. The introduction of advanced phenotyping technologies in recent decades has provided genebank scientists with time and cost-effective screening tools to obtain valuable phenotypic data for more traits on large germplasm collections during routine activities. The utilization of these phenotyping tools, coupled with high-throughput genotyping, will accelerate the use of genetic resources and fast-track the development of more resilient food crops for the future. In this review, we highlight current digital phenotyping methods that can capture traits during annual seed regeneration to enrich genebank phenotypic datasets. Next, we describe strategies for the collection and use of phenotypic data of specific traits for downstream research using high-throughput phenotyping technology. Finally, we examine the challenges and future perspectives of genebank phenomics.
Early vigour of seedlings is a beneficial trait of field pea (Pisum sativum L.) that contributes to weed control, water use efficiency and is likely to contribute to yield under certain environments. ...Although breeding is considered the most effective approach to improve early vigour of field pea, the absence of a robust and high-throughput phenotyping tool to dissect this complex trait is currently a major obstacle of genetic improvement programs to address this issue. To develop this tool, separate trials on 44 genetically diverse field pea genotypes were conducted in the automated plant phenotyping platform of Plant Phenomics Victoria, Horsham and in the field, respectively. High correlation between estimated plant parameters derived from the automated phenotyping platform and important early vigour traits such as shoot biomass, leaf area and plant height indicated that the derived plant parameters can be used to predict vigour traits in field pea seedlings. Plant growth analysis demonstrated that the "broken-stick" model fitted well with the growth pattern of all field pea genotypes and can be used to determine the linear growth phase. Further analysis suggested that the estimated plant parameters collected at the linear growth phase can effectively differentiate early vigour across field pea genotypes. High correlation between normalised difference vegetation indices captured from the field trial and estimated shoot biomass and top-view area confirmed the consistent performance of early vigour field pea genotypes under controlled and field environments. Overall, our results demonstrated that this robust screening tool is highly applicable and will enable breeding programs to rapidly identify early vigour traits and utilise germplasm to contribute to the genetic improvement of field peas.
Globally, viral diseases impair the growth and vigor of cultivated crops such as grains, leading to a significant reduction in quality, marketability, and competitiveness. As an island nation, ...Australia has a distinct advantage in using its border to prevent the introduction of damaging viruses, which threaten the continental agricultural sector. However, breeding programs in Australia rely on imported seeds as new sources of genetic diversity. As such, it is critical to remain vigilant in identifying new and emerging viral pathogens, by ensuring the availability of accurate genomic diagnostic tools at the grain biosecurity border. High-throughput sequencing offers game-changing opportunities in biosecurity routine testing. Genomic results are more accurate and informative compared to traditional molecular methods or biological indexing. The present work contributes to strengthening accurate phytosanitary screening, to safeguard the Australian grains industry, and expedite germplasm release to the end users.
•Pigeonpea is a valuable grain legume for human nutrition and sustainable agriculture.•Crop wild relatives (CWR) are useful in pigeonpea breeding.•Pigeonpea CWR occur from South Asia to Australia in ...a diversity of soils and climates.•Conservation of these species is insufficient, constraining their present and future use.•We prioritize germplasm collecting for potential use for abiotic stress tolerance.
Pigeonpea Cajanus cajan (L.) Millsp. is a versatile, stress-tolerant, and nutritious grain legume, possessing traits of value for enhancing the sustainability of dry sub-tropical and tropical agricultural systems. The use of crop wild relatives (CWR) in pigeonpea breeding has been successful in providing important resistance, quality, and breeding efficiency traits to the crop. Current breeding objectives for pigeonpea include increasing its tolerance to abiotic stresses, including heat, cold, drought, and waterlogging. Here we assess the potential for pigeonpea CWR to be further employed in crop improvement by compiling wild species occurrence and ex situ conservation information, producing geographic distribution models for the species, identifying gaps in the comprehensiveness of current germplasm collections, and using ecogeographic information to identify CWR populations with the potential to contribute agronomic traits of priority to breeders. The fifteen prioritized relatives of pigeonpea generally occur in South and Southeast Asia to Australia, with the highest concentrations of species in southern India and northern Australia. These taxa differ considerably among themselves and in comparison to the crop in their adaptations to temperature, precipitation and edaphic conditions. We find that these wild genetic resources are broadly under-represented in ex situ conservation systems, with 80% of species assessed as high priority for further collecting, thus their availability to plant breeders is insufficient. We identify species and highlight geographic locations for further collecting in order to improve the completeness of pigeonpea CWR germplasm collections, with particular emphasis on potential traits for abiotic stress tolerance.
Grain size and weight are two of the most important determinants of crop yield. Key genes associated with the grain size and weight have been identified in major crops. However, studies on the ...genetic basis of the grain size and weight related genes in wild
Sorghum
are limited. In this study, we analysed the variation of grain size related genes using variant analysis of 15 accessions across one cultivated and six tertiary gene pool species representing the five subgenera of
Sorghum
. A wide variation in grain size related parameters was observed. The highest grain weight, width, and thickness was observed for the accession
S. bicolor
(L.) Moench
314,746
, while the highest grain length was observed for the accession
S. macrospermum
E.D. Garber
302,367
. The wild sorghum species exhibited high morphological diversity. The six candidate genes related to grain size,
Sobic.001G335800
(
qGW7/GL7
)
, Sobic.001G341700
(
GS3
)
, Sobic.002G257900
(
GW8
)
, Sobic.003G035400
(
GW5/qSW5
)
, Sobic.004G107300
(
GW2
)
,
and
Sobic.009G053600
(
GS5
) showed polymorphism in the coding sequence regions including variants generating premature stop codons. These variants might contribute to the observed variation in grain size and weight. The tertiary wild sorghum species may be a useful source of genes for understanding and engineering grain size in sorghum and other cereals.
Main conclusion
Australian native species of sorghum contain negligible amounts of dhurrin in their leaves and the cyanogenesis process is regulated differently under water-stress in comparison to ...domesticated sorghum species.
Cyanogenesis in forage sorghum is a major concern in agriculture as the leaves of domesticated sorghum are potentially toxic to livestock, especially at times of drought which induces increased production of the cyanogenic glucoside dhurrin. The wild sorghum species endemic to Australia have a negligible content of dhurrin in the above ground tissues and thus represent a potential resource for key agricultural traits like low toxicity. In this study we investigated the differential expression of cyanogenesis related genes in the leaf tissue of the domesticated species
Sorghum bicolor
and the Australian native wild species
Sorghum macrospermum
grown in glasshouse-controlled water-stress conditions using RNA-Seq analysis to analyse gene expression. The study identified genes, including those in the cyanogenesis pathway, that were differentially regulated in response to water-stress in domesticated and wild sorghum. In the domesticated sorghum, dhurrin content was significantly higher compared to that in the wild sorghum and increased with stress and decreased with age whereas in wild sorghum the dhurrin content remained negligible. The key genes in dhurrin biosynthesis,
CYP79A1
,
CYP71E1
and
UGT85B1
, were shown to be highly expressed in
S. bicolor
.
DHR
and
HNL
encoding the dhurrinase and α-hydroxynitrilase catalysing bio-activation of dhurrin were also highly expressed in
S. bicolor
. Analysis of the differences in expression of cyanogenesis related genes between domesticated and wild sorghum species may allow the use of these genetic resources to produce more acyanogenic varieties in the future.
Aluminium (Al) toxicity in acid soils inhibits root elongation and development causing reduced water and nutrient uptake by the root system, which ultimately reduces the crop yield. This study ...established a high throughput hydroponics screening method and identified Al toxicity tolerant accessions from a set of putative acid tolerant lentil accessions. Four-day old lentil seedlings were screened at 5 µM Al (pH 4.5) for three days in hydroponics. Measured pre and post treatment root length was used to calculate the change in root length (ΔRL) and relative root growth (RRG%). A subset of 15 selected accessions were used for acid soil Al screening, and histochemical and biochemical analyses. Al treatment significantly reduced the ΔRL with an average of 32.3% reduction observed compared to the control. Approximately 1/4 of the focused identification of germplasm strategy accessions showed higher RRG% than the known tolerant line ILL6002 which has the RRG% of 37.9. Very tolerant accessions with RRG% of > 52% were observed in 5.4% of the total accessions. A selection index calculated based on all root traits in acid soil screening was highest in AGG70137 (636.7) whereas it was lowest in Precoz (76.3). All histochemical and biochemical analyses supported the hydroponic results as Northfield, AGG70137, AGG70561 and AGG70281 showed consistent good performance. The identified new sources of Al tolerant lentil germplasm can be used to breed new Al toxicity tolerant lentil varieties. The established high throughput hydroponic method can be routinely used for screening lentil breeding populations for Al toxicity tolerance. Future recommendations could include evaluation of the yield potential of the selected subset of accessions under acid soil field conditions, and the screening of a wider range of landrace accessions originating from areas with Al toxic acid soils.
Wild species are potential sources of genetic diversity for crop improvement. Variation in agronomically important traits has been reported in the wild
Cajanus
species however, the Australian wild ...species have not been characterized to date. A subset of four Australian wild
Cajanus acutifolius
(F.Muell.) Maesen accessions and 57 interspecific hybrids of
C. acutifolius
,
Cajanus lanuginosus
(S.T.Reynolds & Pedley) Maesen,
Cajanus lanceolatus
(W.Fitzg.) Maesen, and two
C. cajan
genotypes were investigated to assess the phenotypic diversity for 17 qualitative and six quantitative traits. Significant variation in stem thickness, days to 50% flowering (dff) (f.pr < 0.001), and raceme number (f.pr < 0.021) within a group, and plant height, stem thickness, leaf size and dff (f.pr < 0.001) between groups was found. In contrast to earlier reports, some wild
C. acutifolius
accessions were found to be early (AGG31815WCAJ with 117 days) and medium (AGG316925WCAJ with 140 days) maturating types. Positive correlation of plant height with stem thickness (
r
= 0.714), and dff (
r
= 0.780) was observed in late maturing types. Positive correlation of stem thickness with leaf size (
r
= 0.709), and dff (
r
= 0.760) were identified in all groups. Even though there was a slight negative correlation of the number of racemes with plant height (
r
= − 0.126) and stem thickness (
r
= − 0.190), a considerable positive correlation was observed with secondary (
r
= 0.536) and tertiary (
r
= 0.500) branches. The F1s produced with wild
Cajanus acutifolius
as the female parent were sterile demonstrating the potential for use in hybrid breeding programs.
We describe an experimental closed bioreactor device for studying novel tissue engineered peripheral nerve conduits in vitro. The system integrates a closed loop system consisting of one, two, or ...three experimental nerve conduits connected in series or parallel, with the ability to study novel scaffolds within guidance conduits. The system was established using aligned synthetic microfiber scaffolds of viscose rayon and electrospun polystyrene. Schwann cells were seeded directly into conduits varying from 10 to 80 mm in length and allowed to adhere under 0 flow for 1 h, before being cultured for 4 days under static or continuous flow conditions. In situ viability measurements showed the distribution of live Schwann cells within each conduit and enabled quantification thereafter. Under static culture viable cells only existed in short conduit scaffolds (10 mm) or at the ends of longer conduits (20-80 mm) with a variation in viable cell distribution. Surface modification of scaffold fibers with type-1 collagen or acrylic acid increased cell number by 17% and 30%, respectively. However, a continuous medium flow of 0.8 mL/h was found to increase total cell number by 2.5-fold verses static culture. Importantly, under these conditions parallel viability measurements revealed a ninefold increase compared to static culture. Fluorescence microscopy of scaffolds showed cellular adhesion and alignment on the longitudinal axis. We suggest that such a system will enable a rigorous and controlled approach for evaluating novel conduits for peripheral nerve repair, in particular using hydrolysable materials for the parallel organization of nerve support cells, prior to in vivo study. Biotechnol. Bioeng. 2008;99: 1250-1260.
PDF
