Raboy, 1997). Trace levels (Ͻ5% of total Ins P) of "lower" Ins polyphosphates (Ins bis-, tris-, tetrakis-, and Phytic acid (myo-inositol 1,2,3,4,5,6 hexakisphosphate) is the most pentakisphosphates) are also often observed in mature, abundant form of phosphorus (P) in seeds and is virtually indigestible by humans or non-ruminant livestock. It was hypothesized that one wild-type seeds. Normally, inorganic P (P i ) typically repclass of maize (Zea mays L.) and barley (Hordeum vulgare L.) low resents about 5% (Ϯ3%) of seed total P and all other phytic acid mutations, designated lpa1, interrupt myo-inositol supply forms of organic P (DNA, RNA, free nucleotides, phosduring seed development and may be mutations of the myo-inositol pholipids, sugar phosphates, etc.), referred to here as 1-phosphate synthase (MIPS) gene. This study describes the isolation, cellular P, represent about 10 to 20% of seed total P. inheritance, and genetic mapping of the first rice lpa1 mutation and Substantial variation in seed total P of a given line or reexamines the MIPS/lpa1 candidate gene hypothesis in rice. Grain genotype can result from environmental or genotypic from 3632 rice M2 lines, derived from gamma-irradiated seed, was factors that alter the supply of P to the developing seed. screened for the lpa phenotype. Two mutations, one lethal and oneIn wild-type plants, this variation is mostly due to varianon-lethal, were identified. The non-lethal mutation is phenotypically tion in seed phytic acid P, while the P i and cellular P similar to maize and barley lpa1 mutants and was designated rice lpa1-1. Homozygosity for rice lpa1-1 reduces the phytic acid portion fractions of seed total P tend to remain constant (reof seed P from 71 to 39% and increases the inorganic portion of seed viewed in Raboy, 1997). P from 5 to 32%, with little effect on total seed P. This rice lpa1Chemically induced, non-lethal recessive mutants that mutation was mapped to a 2.2-cM interval on chromosome 2L. A decrease seed phytic acid content have been isolated single-copy rice MIPS gene was mapped to a locus on rice chromosome and genetically mapped in maize (Zea mays L.; Raboy 3 that is orthologous to MIPS loci on maize chromosome 1S (near and Gerbasi, 1996; Raboy et al., 2000) and barley maize lpa1 ) and barley chromosome 4H. Unlike maize lpa1, the rice (Hordeum vulgare L.; Larson et al., 1998; Rasmussen and barley lpa1 mutations loci are clearly distinguishable from this and Hatzak, 1998). These low phytic acid (lpa) mutacanonical MIPS gene. No relationship can be inferred between the tions have the potential to alleviate the environmental maize, barley, and rice lpa1 loci. Although this canonical MIPS gene and nutritional problems associated with phytic acid in may be an appropriate target for controlling seed phytic acid synthesis, modifications of other genes (e.g., maize lpa2, barley lpa1, barley
In the interest of diversifying the global food system, improving human nutrition, and making agriculture more sustainable, there have been many proposals to domesticate wild plants or complete the domestication of semidomesticated orphan crops. However, very few new crops have recently been fully domesticated. Many wild plants have traits limiting their production or consumption that could be costly and slow to change. Others may have fortuitous preadaptations that make them easier to develop or feasible as high‐value, albeit low‐yielding, crops. To increase success in contemporary domestication of new crops, we propose a pipeline approach, with attrition expected as species advance through the pipeline. We list criteria for ranking domestication candidates to help enrich the starting pool with more preadapted, promising species. We also discuss strategies for prioritizing initial research efforts once the candidates have been selected: developing higher value products and services from the crop, increasing yield potential, and focusing on overcoming undesirable traits. Finally, we present new‐crop case studies that demonstrate that wild species’ limitations and potential (in agronomic culture, shattering, seed size, harvest, cleaning, hybridization, etc.) are often only revealed during the early phases of domestication. When nearly insurmountable barriers were reached in some species, they have been (at least temporarily) eliminated from the pipeline. Conversely, a few species have moved quickly through the pipeline as hurdles, such as low seed weight or low seed number per head, were rapidly overcome, leading to increased confidence, farmer collaboration, and program expansion.
Development of the first consensus genetic map of intermediate wheatgrass gives insight into the genome and tools for molecular breeding. Intermediate wheatgrass (Thinopyrum intermedium) has been identified as a candidate for domestication and improvement as a perennial grain, forage, and biofuel crop and is actively being improved by several breeding programs. To accelerate this process using genomics-assisted breeding, efficient genotyping methods and genetic marker reference maps are needed. We present here the first consensus genetic map for intermediate wheatgrass (IWG), which confirms the species' allohexaploid nature (2n = 6x = 42) and homology to Triticeae genomes. Genotyping-by-sequencing was used to identify markers that fit expected segregation ratios and construct genetic maps for 13 heterogeneous parents of seven full-sib families. These maps were then integrated using a linear programming method to produce a consensus map with 21 linkage groups containing 10,029 markers, 3601 of which were present in at least two populations. Each of the 21 linkage groups contained between 237 and 683 markers, cumulatively covering 5061 cM (2891 cM--Kosambi) with an average distance of 0.5 cM between each pair of markers. Through mapping the sequence tags to the diploid (2n = 2x = 14) barley reference genome, we observed high colinearity and synteny between these genomes, with three homoeologous IWG chromosomes corresponding to each of the seven barley chromosomes, and mapped translocations that are known in the Triticeae. The consensus map is a valuable tool for wheat breeders to map important disease-resistance genes within intermediate wheatgrass. These genomic tools can help lead to rapid improvement of IWG and development of high-yielding cultivars of this perennial grain that would facilitate the sustainable intensification of agricultural systems.
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