A combination of three gene alterations that make the seeds fall from the plant less easily may have contributed to the historical development of cultivated rice from wild rice plants, according to a new study.
These findings illuminate the early history and, perhaps, pave the way for the future creation of more productive rice cultivars.
Genetic mutation in rice cultivation
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In their research, the scientists found that although the three mutations individually have minimal impact, when all three mutations are present, the rice plant's panicles retain more of its seeds, increasing crop production, as per ScienceDaily.
When our ancestors found and began to nurture rice plants that do not shed their seeds readily, paving the door for reliable rice production, it is thought that wild rice was first domesticated.
It is believed that these study findings may help design high-yield rice cultivars where every grain can be gathered, decreasing wastage, and future improvements to the ease with which rice seeds fall.
In their research, the scientists found that although the three mutations individually have minimal impact, when all three mutations are present, the rice plant's panicles retain more of its seeds, increasing crop production.
When our ancestors found and began to nurture rice plants that do not shed their seeds readily, paving the door for reliable rice production, it is thought that wild rice was first domesticated.
It is believed that these study findings may help design high-yield rice cultivars where every grain can be gathered, decreasing wastage, and future improvements to the ease with which rice seeds fall (i.e. making the crop more straightforward to thresh).
The abscission layer, which forms at the base of every rice seed, is what causes the seeds to break. In addition to the previously stated sh4 gene mutation, the researchers discovered that a single nucleotide change (from cytosine to thymine) in the DNA of the qSH3 gene is necessary to block the abscission layer.
The most widely grown varieties of rice across the world have this qSH3 gene mutation (indica and japonica).
Individual seed shattering-related mutations, such as those in the genes qSH3 and sh4, cannot by themselves stop seed shattering in wild rice plants.
The creation of the abscission layer, which is necessary for seed breaking, was shown to be somewhat suppressed by the combination of the sh4 and qSH3 mutations, the researchers found.
Genes and Mutations in the Development of Vegetative Organs
With an alternating phyllotaxy, the sides of the shoot apical meristem (SAM) produce leaves progressively throughout vegetative growth, as per Oxford Academic.
In this stage of growth, culm, crown roots, and lateral roots are also developed. In rice, several causative genes have been identified as well as a huge number of mutants with defects in the development of various organs. Four sets of mutations and genes related to vegetative organ development have been identified:
1. genes selectively expressed in the SAM;
2. mutant leaves;
3. mutant culms
4. mutant roots.
Mutant leaves
A leaf morphology group and a leaf color group are the two main categories of mutants that have been found in the study of leaf development.
The leaf morphology group includes three QTLs that govern leaf angle, leaf length, and leaf breadth, as well as seven different mutant types: curled leaves, dripping-wet leaves, narrow leaves, drooping leaves, blade-sheath border defect leaves, glabrous leaves, and hairy leaves.
Deformed culms
Eight kinds of culm mutations can be identified: dwarfism/elongation, floating, tiller development, tiller angle, brittleness, thickness, twisted, and others.
Mutants defective in gibberellin synthesis, gibberellin signaling, brassinosteroid synthesis, and brassinosteroid signaling are included in the dwarfism/elongation category.
