Domestication Loci Controlling Panicle Shape, Seed Shattering, and Seed Awning

Ishii, Takashige; Ishikawa, Ryo

doi:10.1007/978-981-10-7461-5_12

Cited by 6 publications

(6 citation statements)

References 19 publications

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“…Because sh4 and qSH1 were identified in QTL analyses as having large effects on seed shattering, they were believed to be the genes explaining the loss of seed shattering during rice domestication. However, recent research through longer term experiments using plant materials with wild rice introgression lines have proved this view to be over-simplified (Ishii and Ishikawa 2018; see discussion below).…”

Section: Loss Of Seed Shatteringmentioning

confidence: 99%

“…Therefore, it would be more accurate to evaluate domestication-related mutated alleles in the wild rice genetic background. Therefore, research carried out at Kobe University has focused on maintaining a wild population of rice (the annual form of O. rufipogon sensu lato) and introgressing alleles from domesticated lines into this population to assess the impact of hypothesised domestication alleles on rice characters and through hand-harvesting experiments (Ishii and Ishikawa 2018). This is the opposite of most functional genetics which introgresses targeted wild rice alleles into plants of domesticated rice background, which means that interactions with other genes selected in domesticated populations can go undetected.…”

Section: What Traits Were Targeted For Selection In Early Rice Domestication?mentioning

confidence: 99%

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Genetic evaluation of domestication-related traits in rice: implications for the archaeobotany of rice origins

Ishikawa

Castillo

Fuller

2020

Archaeol Anthropol Sci

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Domestication is the process in which preferred genetic changes in wild plants and animals have been selected by humans. In other words, domesticated plants have become adapted to being part of human-managed ecosystems. Asian cultivated rice, Oryza sativa L., is one of the most important crops in the world and is known to have been domesticated from its wild ancestor, O. rufipogon. Many morphological changes in cultivated rice have been beneficial to humans in terms of increased efficiency of cultivation and yield that supported the development of human civilisations. The genetic mechanisms of these changes have been extensively studied since rice genome sequences were determined, and based on genome analyses, the origin of rice has been widely discussed. Most of the domestication-related traits and genes are, however, often evaluated based on the genetic background of cultivated rice, leading to misinterpretation of rice domestication. Here, we review several genetic changes and discuss the importance of evaluating these traits in the wild rice genetic background to understand the process of rice domestication. In this review, we also provide a phenotypic evaluation of domestication-related traits.

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Section: Loss Of Seed Shatteringmentioning

confidence: 99%

Section: What Traits Were Targeted For Selection In Early Rice Domestication?mentioning

confidence: 99%

Genetic evaluation of domestication-related traits in rice: implications for the archaeobotany of rice origins

Ishikawa

Castillo

Fuller

2020

Archaeol Anthropol Sci

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“…Magwa et al 2016: 641, table 1) for a comparison between two Chinese regions, Hainan and Wuhan). iv) Within the same wild as well as domesticated species, the awn length is variable between primary and secondary branches or tillers, and among the five uppermost spikelets on the top primary branch in the panicles (Ikemoto et al 2017;Ishii and Ishikawa 2018).…”

Section: Phenotypic Diversitymentioning

confidence: 99%

“…This implies that single change in the wild ancestor may not have had immediate phenotypic effects until the overall genetic framework was sufficiently modified by other mutations (Ray and Chakraborty 2018). Under this scenario, other mechanisms to enhance seed retention would also have been selected upon, such as a mechanism based on changes of the architecture of the inflorescence (Ishii et al 2013;Ishii and Ishikawa 2018); such as in Oryza rufipogon, the wild progenitor of domesticated rice (O. sativa), the panicle could be either open or spreading. However, Ishii et al (2013) discovered that one of the many early genetic mutations in rice, namely a mutation in a single locus, the SPR3 locus on chromosome 4, converts the open-panicle architecture of the wild species to the closed panicle of domesticated rice, leading to approximately 50% gain in number of seeds recovered at maturity over a typical wild spreading inflorescence type.…”

Section: The Persistence Of Long Awns Beyond the Domestication Periodmentioning

confidence: 99%

Awn Reduction and the Domestication of Asian Rice: A Syndrome or Crop Improvement Trait?

2019

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Although wild progenitors of Asian cultivated rice have long awns, they are shorter or absent in domesticated landraces and cultivars. Thus, one may wonder when and why such transition from awned to awnless has occurred, i.e., is the reduction of awns a domestication syndrome trait or a trait emerged during crop improvement? The proponents of an evolutionary model of rice domestication consider the loss/reduction of seed dispersal aids as a key domestication syndrome trait, apart from the fixation of seed retention. We challenge this view by showing that early cultivators had incentives for selecting long awns before and even after the fixation of the non-shattering trait. This is because long awns prevented seeds predation by animal and facilitated the harvest by means of the basket beating method, that implies their presence improved yield and labor-efficiency. Our arguments also reveal that awns perhaps have persisted long after domestication and even after the introduction of sickles. Taken together, the reduction of awns may not fit to be a domestication syndrome trait but can most plausibly be considered as a crop improvement trait.

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“…This may enhance self-pollination and the accumulation of recessive alleles at the seed-shattering loci. After the emergence of non-seed-shattering plants, seed awning may have become an undesirable trait because long awns disturb seed harvesting and handling (Ishii and Ishikawa 2018).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Domestication Loci Associated with Awnlessness in Cultivated Rice, Oryza sativa

Amarasinghe

Kuwata

Nishimura

et al. 2020

Rice

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Background Awns are bristle-like organs at the tips of the glumes. Wild rice has maintained long awns for successful seed propagation through seed dispersal. Seed awning is an interesting trait in rice domestication. Long awns might have been beneficial for seed gatherers in the initial phase of domestication; however, awnless phenotypes were preferably selected in a later phase with non-seed-shattering plants. Investigation of domestication loci associated with awnlessness in cultivated rice will be useful in clarifying the process and history of rice domestication. Results Quantitative trait locus (QTL) analysis for seed awning was carried out using a BC3F2 population between Oryza sativa IR36 (a cultivated donor parent with awnless phenotype) and O. rufipogon W630 (a wild recurrent parent with awns). As a result, two QTLs on chromosome 4 (corresponding to An-1 and LABA1) and one on chromosome 2 (designated as qAWNL2) were detected. Gene interaction among three seed-awning QTLs were further examined with the plants having eight different combinations of homozygous genotypes. Their awn length variation indicated that the IR36 alleles at these loci had the additive awnlessness effects in the genetic background of wild rice. The shortest awn length was observed for the plants having IR36 homozygous alleles at all loci, giving about 75% reduction in awn length. By the fine mapping, the candidate region of the novel qAWNL2 locus was delimited in a 157.4-kb region containing 22 predicted genes in Nipponbare genome. Conclusions QTL analysis revealed that three loci, An-1, LABA1 and qAWNL2, were mainly responsible for the awnlessness of O. sativa IR36. In the wild genetic background, loss-of-function alleles at three awning loci showed additive effects on length reduction. In rice domestication, awnless forms may be gradually generated through the accumulation of mutations at awning loci.

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Domestication Loci Controlling Panicle Shape, Seed Shattering, and Seed Awning

Cited by 6 publications

References 19 publications

Genetic evaluation of domestication-related traits in rice: implications for the archaeobotany of rice origins

Genetic evaluation of domestication-related traits in rice: implications for the archaeobotany of rice origins

Awn Reduction and the Domestication of Asian Rice: A Syndrome or Crop Improvement Trait?

Evaluation of Domestication Loci Associated with Awnlessness in Cultivated Rice, Oryza sativa

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