bims-plasge Biomed News
on Plastid genes
Issue of 2024‒03‒17
two papers selected by
Vera S. Bogdanova, Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences
  1. Cytoplasmic genome contributions to domestication and improvement of modern maize.
  2. Physical seed dormancy in pea is genetically separable from seed coat thickness and roughness.
  1. BMC Biol. 2024 Mar 13. 22(1): 64
    Cytoplasmic genome contributions to domestication and improvement of modern maize.
    Shuai Cao, Huanhuan Zhang, Yang Liu, Yi Sun, Z Jeffrey Chen.
      BACKGROUND: Studies on maize evolution and domestication are largely limited to the nuclear genomes, and the contribution of cytoplasmic genomes to selection and domestication of modern maize remains elusive. Maize cytoplasmic genomes have been classified into fertile (NA and NB) and cytoplasmic-nuclear male-sterility (CMS-S, CMS-C, and CMS-T) groups, but their contributions to modern maize breeding have not been systematically investigated.RESULTS: Here we report co-selection and convergent evolution between nuclear and cytoplasmic genomes by analyzing whole genome sequencing data of 630 maize accessions modern maize and its relatives, including 24 fully assembled mitochondrial and chloroplast genomes. We show that the NB cytotype is associated with the expansion of modern maize to North America, gradually replaces the fertile NA cytotype probably through unequal division, and predominates in over 90% of modern elite inbred lines. The mode of cytoplasmic evolution is increased nucleotypic diversity among the genes involved in photosynthesis and energy metabolism, which are driven by selection and domestication. Furthermore, genome-wide association study reveals correlation of cytoplasmic nucleotypic variation with key agronomic and reproductive traits accompanied with the diversification of the nuclear genomes.
    CONCLUSIONS: Our results indicate convergent evolution between cytoplasmic and nuclear genomes during maize domestication and breeding. These new insights into the important roles of mitochondrial and chloroplast genomes in maize domestication and improvement should help select elite inbred lines to improve yield stability and crop resilience of maize hybrids.
    Keywords:  Convergent evolution; Cytoplasmic genomes; Domestication; Hybrid; Improvement; Maize
    DOI:  https://doi.org/10.1186/s12915-024-01859-4
  2. Front Plant Sci. 2024 ;15 1359226
    Physical seed dormancy in pea is genetically separable from seed coat thickness and roughness.
    Owen R Williams, Jacqueline K Vander Schoor, Jakob B Butler, Valérie F G Hecht, James L Weller.
      Introduction: The seeds of wild pea (Pisum) exhibit marked physical dormancy due to impermeability of the seed coat to water, and the loss of this dormancy is thought to have been critical for domestication. Wild pea seed coats are also notably thick and rough, traits that have also reduced during domestication and are anecdotally linked to increased permeability. However, how these traits specifically interact with permeability is unclear.Methods: To investigate this, we examined the genetic control of differences in seed coat characteristics between wild P. sativum ssp. humile and a non-dormant domesticated P. s. sativum accession in a recombinant inbred population. QTL effects were confirmed and their locations refined in segregating F4/5 populations.
    Results: In this population we found a moderate correlation between testa thickness and permeability, and identified loci that affect them independently, suggesting no close functional association. However, the major loci affecting both testa thickness and permeability collocated closely with Mendel's pigmentation locus A, suggesting flavonoid compounds under its control might contribute significantly to both traits. We also show that seed coat roughness is oligogenic in this population, with the major locus independent of both testa thickness and permeability, suggesting selection for smooth seed was unlikely to be due to effects on either of these traits.
    Discussion: Results indicate loss of seed coat dormancy during domestication was not primarily driven by reduced testa thickness or smooth seededness. The close association between major permeability and thickness QTL and Mendel's 'A' warrant further study, particularly regarding the role of flavonoids.
    Keywords:  Pisum; domestication; flavonoid; gritty; permeability; seed coat; seed dormancy
    DOI:  https://doi.org/10.3389/fpls.2024.1359226
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