bims-plasge Biomed News
on Plastid genes
Issue of 2018‒09‒23
three papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Theor Appl Genet. 2018 Sep 15.
      KEY MESSAGE: BnA10.LMI1 positively regulates the development of leaf lobes in Brassica napus, and cis-regulatory divergences cause the different allele effects. Leaf shape is an important agronomic trait, and large variations in this trait exist within the Brassica germplasm. The lobed leaf is a unique morphological characteristic for Brassica improvement. Nevertheless, the molecular basis of leaf lobing in Brassica is poorly understood. Here, we show that an incompletely dominant locus, BnLLA10, is responsible for the lobed-leaf shape in rapeseed. A LATE MERISTEM IDENTITY1 (LMI1)-like gene (BnA10.LMI1) encoding an HD-Zip I transcription factor is the causal gene underlying the BnLLA10 locus. Sequence analysis of parental alleles revealed no sequence variations in the coding sequences, whereas abundant variations were identified in the regulatory region. Consistent with this finding, the expression levels of BnLMI1 were substantially elevated in the lobed-leaf parent compared with its near-isogenic line. The knockout mutations of BnA10.LMI1 gene were induced using the CRISPR/Cas9 system in both HY (the lobed-leaf parent) and J9707 (serrated leaf) genetic backgrounds. BnA10.LMI1 null mutations in the HY background were sufficient to produce unlobed leaves, whereas null mutations in the J9707 background showed no obvious changes in leaf shape compared with the control. Collectively, our results indicate that BnA10.LMI1 positively regulates the development of leaf lobes in B. napus, with cis-regulatory divergences causing the different allelic effects, providing new insights into the molecular mechanism of leaf lobe formation in Brassica crops.
  2. BMC Plant Biol. 2018 Sep 15. 18(1): 195
      BACKGROUND: Soil salinity and/or alkalinity impose a major constraint over crop yield and quality. An understanding of the molecular basis of the plant response to these stresses could inform the breeding of more tolerant varieties. The bread wheat cultivar SR3 exhibits an enhanced level of salinity tolerance, while SR4 is distinguished by its superior tolerance of alkalinity.RESULTS: The small RNA and degradome sequencing was used to explore the miRNAs and corresponding targets associated with the superior stress tolerance of the SR lines. An examination of the small RNA content of these two closely related lines revealed the presence of 98 known and 219 novel miRNA sequences. Degradome libraries were constructed in order to identify the targets of the miRNAs, leading to the identification of 58 genes targeted by 26 of the known miRNAs and 549 targeted by 65 of the novel ones. The function of two of the stress-responsive miRNAs was explored using virus-induced gene silencing.
    CONCLUSIONS: This analysis indicated that regulation mediated by both auxin and epigenetic modification can be important in determining both salinity and alkalinity tolerance, while jasmonate signaling and carbohydrate metabolism are important for salinity tolerance, as is proton transport for alkalinity tolerance.
    Keywords:  Alkalinity; Degradome; Salinity; Small RNA; Wheat; miRNA
  3. Plant Physiol Biochem. 2018 Aug 29. pii: S0981-9428(18)30392-9. [Epub ahead of print]132 222-228
      Waterlogging is one of the most common abiotic stress types in wheat production in many rainy areas of the world. Two locally widely grown winter wheat (Triticum aestivum L. cv Yumai 34 and Yangmai 9) were subjected to post-anthesis waterlogging in a pot experiment to investigate the impacts of waterlogging on the starch synthesis and the physiochemical properties. Post-anthesis waterlogging significantly decreased grain weight and affected the content of starch components. Waterlogging down-regulated the activity and expression of genes encoding soluble starch synthase [SSS (EC], while up-regulated those of the granule bound starch synthase I [GBSSI (EC:]. This further resulted in decreased amylopectin content and increased amylose content. Waterlogging also caused a reduction in the number of starch granules, while increased the mean diameter of starch granules in mature grains, which was mainly due to an increase in the volume frequency percent of the A-type starch granules. Waterlogging also lowered the peak viscosity and trough viscosity of starch, but did not affect the breakdown viscosity and peak time. We concluded that the modified expressions of the starch synthase encoding genes were responsible for the changed size distribution of starch granules, which finally affected the starch pasting properties of wheat growing under post-anthesis waterlogging conditions.
    Keywords:  GBSS; SSS; Starch components; Starch granule size; Waterlogging; Wheat