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Abstract The modification of seed shattering has been a recurring theme in rice evolution. The wild ancestor of cultivated rice disperses its seeds, but reduced shattering was selected during multiple domestication events to facilitate harvesting. Conversely, selection for increased shattering occurred during the evolution of weedy rice, a weed invading cultivated rice fields that has originated multiple times from domesticated ancestors. Shattering requires formation of a tissue known as the abscission zone (AZ), but how the AZ has been modified throughout rice evolution is unclear. We quantitatively characterized the AZ characteristics of relative length, discontinuity, and intensity in 86 cultivated and weedy rice accessions. We reconstructed AZ evolutionary trajectories and determined the degree of convergence among different cultivated varieties and among independent weedy rice populations. AZ relative length emerged as the best feature to distinguish high and low shattering rice. Cultivated varieties differed in average AZ morphology, revealing lack of convergence in how shattering reduction was achieved during domestication. In contrast, weedy rice populations typically converged on complete AZs, irrespective of origin. By examining AZ population-level morphology, our study reveals its evolutionary plasticity, and suggests that the genetic potential to modify the ecologically and agronomically important trait of shattering is plentiful in rice lineages.
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Experimental methods for phenotypic and molecular analyses of seed shattering in cultivated and weedy rice
The seed shattering trait has been repeatedly reshaped during rice evolution. Reduced in cultivated rice and increased in weedy rice, shattering is of great agronomic importance because of its association with yield losses. Since its first descriptions, the phenotypic patterns and the genetic regulation of cultivated and weedy rice seed shattering have been extensively studied, with a variety of methods and techniques. The aim of this review is to discuss and recommend the most suitable experimental methods for phenotypic and molecular evaluation of seed shattering in cultivated and weedy rice. Rice seed shattering must be quantified, preferably, by breaking tensile strength (BTS) assays, because other methods are more prone to human errors. The evaluation time is particularly important, and the developmental stages of the panicles measured need to be recorded. QTL analyses and GWAS studies are suitable for discovery of genes influencing shattering, but the resulting genes may only be relevant in the parental lines or the populations used. The variety of cultivated rice and evolutionary origin of weedy rice accessions has a great influence on results of rice seed shattering phenotypic and genotypic analyses and needs to always be taken into account.
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- Award ID(s):
- 1947609
- PAR ID:
- 10586078
- Publisher / Repository:
- Journal of the Brazilian Weed Science Society
- Date Published:
- Journal Name:
- Advances in Weed Science
- Volume:
- 41
- ISSN:
- 2675-9462
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.51694/AdvWeedSci/2023;41:00030
