Commercial Cultivation of Australian Wild Oryza spp.: A Review and Conceptual Framework for Future Research Needs

Wild Oryza species are being targeted for commercial cultivation due to their high nutritional grain profile, and their association with Aboriginal people in many regions. Australian wild Oryza species have potential as high-value, low-volume, culturally identified, and nutritious food, especially in gourmet food, tourism, restaurants, and value-added products. However, the basic agronomic protocols for their cultivation as a field crop are unknown. In this review, we identify the major factors supporting the commercial production of wild Oryza, including their stress-tolerant capacity, excellent grain quality attributes, and Indigenous cultural identification of their grains. The key challenges to be faced during the development of a wild rice industry are also discussed which include management barriers, processing issues, undesirable wild traits, and environmental concern. This manuscript proposes the use of agronomic research, in combination with breeding programs, as an overarching framework for the conceptualization and implementation of a successful wild rice industry, using the North American wild rice industry as a case study. The framework also suggests an integrated system that connects producers, industry, and government stakeholders. The suggested procedures for developing a wild rice industry in Australia are also applicable for other wild Oryza species.

Characterization of Wild Rice - Oryza Species Complexes in Sri Lanka

Rice is the staple food crop in Sri Lanka, which occupies 34% (0.77/million ha) of the total cultivated area. Sri Lanka currently produces 2.7 million tonnes of rough rice annually and satisfies around 95% of the domestic requirement. In Sri Lanka, genus Oryza consists of two species complexes, O. sativa (AA) and O. officinalis (CC). These two complexes are both pan tropical and have very similar overall distribution. Five wild rice species are reported in Sri Lanka, (O. nivara [AA], O. rufipogan (AA) O. eichengeri [CC], O. rhizomatis (CC) and O. granulate (GG). O. rhizomatis has been reported only in Sri Lanka and considered endemic to Sri Lanka. Recent studies demonstrated, the reliance on single source of information could mislead results in the phylogenetic inferences due to analytical inconsistency and biological processes. Therefore, exact number of wild rice species in Sri Lanka becomes uncertain and the necessity arises to assess Oryza species complexes in Sri Lanka using morphological, anatomical, and molecular information to enumerate number of species within each Oryza complex and characterization of species and species complexes. The study revealed, characterization of wild rice species, to a certain extent, can be made through morphological and anatomical characters, specially lamina anatomical characters. Molecular information is more reliable in delimitation of wild rice species complexes in Sri Lanka. O. rhizomatis and O. eichingeri (CC) are well separated from the rest of wild rice species (AA). Molecular data revealed, O. nivara and O. rufipogon have undergone independent evolution within Sri Lanka. Well separated five wild rice species are existing in Sri Lanka. Studies on ecological resilience of morphological, anatomical, and molecular studies are very useful for species enumeration of wild rice complexes in Sri Lanka. The findings led to conclude that wild rice species in Sri Lanka are “ecological swarms” and represents allopatric or sympatric populations. A comprehensive knowledge on genetic diversity and population structure of wild rice germplasm in Sri Lanka provides useful information to include these locally adapted and evolved wild rice species in rice crop improvement/breeding.

In Silico Characterization of a Cyclin Dependent Kinase -A (CDKA) and its Coding Gene in some Oryza Species

Rice (Oryza sativa) is a fundamental food for the majority of world population. Cyclin Dependent Kinase -A (CDKA) accelerates transition through different stages of cell cycle and contributes in gametes formation. In the present investigation, a CDKA encoding gene along with the corresponding protein were characterized in O. sativa Indica Group, O. glaberrima, O. barthii, O. brachyantha, O. glumipatula, O. longistaminata, O. meridionalis, O. nivara, O. punctata and O. rufipogon using in silico analyses. The results reflected little variation in most species except O. longistaminata and O. brachyantha. Compared with the remaining species, O. longistaminata lacked a negative regulatory binding site and had a modified cyclin binding site (PSTAICE instead of PSTAIRE) that may lead to future characterization of a new distinct subclass of CDKAs. O. brachyantha had a modified SUC/CKS (suppressor of CDC2/cyclin dependent-kinase regulatory subunit)-binding motif. The observed variations can be exploited through traditional breeding or molecular approaches to manipulate cell division and growth of cultivated Oryza species.

Substitution mapping of the major quantitative trait loci controlling stigma exsertion rate from Oryza glumaepatula

Background: Stigma exsertion rate (SER) is a key determinant for the outcrossing ability of male sterility lines (MSLs) in hybrid rice seed production. In the process of domestication, the outcrossing ability of cultivated rice varieties decreased, while that of wild Oryza species kept strong. Here, we detected the quantitative trait loci (QTLs) controlling SER using a set of single-segment substitution lines (SSSLs) derived from O. glumaepatula , a wild Oryza species. Results: Seven QTLs for SER were located on 5 chromosomes. qSER-1a and qSER-1b were located on chromosome 1. qSER-3a and qSER-3b were mapped on chromosome 3, and qSER-3b was further located at an estimated interval of 898.8kb by secondary substitution mapping. qSER-5 , qSER-9 and qSER-10 were identified on chromosomes 5, 9 and 10, respectively, and qSER-9 was delimited to an estimated region of 551.9kb by secondary substitution mapping. The additive effects of the 7 QTLs ranged from 10.6% to 14.8%, which were higher than those of most loci for SER reported previously. Conclusions: qSER-1a and qSER-1b are novel loci for SER on chromosome 1. All of the 7 QTLs have major effects on SER. The major QTLs of SER will help to develop MSLs with strong outcrossing ability.