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The ERECTA (ER) family of genes, encoding leucine-rich repeat receptor-like kinase (RLK), influences complex morphological and physiological aspects of plants. Modulation of ER signaling leads to abiotic stress tolerance in diverse plant species. However, whether the gain in stress tolerance is accompanied with desirable agronomic performance is not clearly known. In this study, soybean plants potentially suppressed in ER signaling were evaluated for the phenotypic performance and drought response in the greenhouse. These plants expressed a dominant-negative Arabidopsis thaliana ER ( AtER ) called Δ Kinase to suppress ER signaling, which has previously been linked with the tolerance to water deficit, a major limiting factor for plant growth and development, directly compromising agricultural production. With the aim to select agronomically superior plants as stress-tolerant lines, transgenic soybean plants were subjected to phenotypic selection and subsequently to water stress analysis. This study found a strong inverse correlation of Δ Kinase expression with the agronomic performance of soybean plants, indicating detrimental effects of expressing Δ Kinase that presumably led to the suppression of ER signaling. Two lines were identified that showed favorable agronomic traits and expression of Δ Kinase gene, although at lower levels compared with the rest of the transgenic lines. The drought stress analysis on the progenies of these lines, however, showed that these plants were more susceptible to water-deficit stress as compared with the non-transgenic controls. The selected transgenic plants showed greater stomata density and conductance, which potentially led to higher biomass, and consequently more water demand and greater susceptibility to the periods of water withholding. 

Starch biosynthesis is a complex process underlying grain chalkiness in rice in a genotype-dependent manner. Coordinated expression of starch biosynthesis genes is important for producing translucent rice grains, while disruption in this process leads to opaque or chalky grains. To better understand the dynamics of starch biosynthesis genes in grain chalkiness, six rice genotypes showing variable chalk levels were subjected to gene expression analysis during reproductive stages. In the chalky genotypes, peak expression of the large subunit genes of ADP-glucose pyrophosphorylase (AGPase), encoding the first key step in starch biosynthesis, occurred in the stages before grain filling commenced, creating a gap with the upregulation of starch synthase genes, granule bound starch synthase I (GBSSI) and starch synthase IIA (SSIIA). Whereas, in low-chalk genotypes, AGPase large subunit genes expressed at later stages, generally following the expression patterns of GBSSI and SSIIA. However, heat treatment altered the expression in a genotype-dependent manner that was accompanied by transformed grain morphology and increased chalkiness. The suppression of AGPase subunit genes during early grain filling stages was observed in the chalky genotypes or upon heat treatment, which could result in a limited pool of ADP-Glucose for synthesizing amylose and amylopectin, the major components of the starch. This suboptimal starch biosynthesis process could subsequently lead to inefficient grain filling and air pockets that contribute to chalkiness. In summary, this study suggests a mechanism of grain chalkiness based on the expression patterns of the starch biosynthesis genes in rice. 

Abstract The Snf1-related protein kinase 1 (SnRK1) is the plant homolog of the heterotrimeric AMP-activated protein kinase/sucrose non-fermenting 1 (AMPK/Snf1), which works as a major regulator of growth under nutrient-limiting conditions in eukaryotes. Along with its conserved role as a master regulator of sugar starvation responses, SnRK1 is involved in controlling the developmental plasticity and resilience under diverse environmental conditions in plants. In this review, through mining and analyzing the interactome and phosphoproteome data of SnRK1, we are highlighting its role in fundamental cellular processes such as gene regulation, protein synthesis, primary metabolism, protein trafficking, nutrient homeostasis, and autophagy. Along with the well-characterized molecular interaction in SnRK1 signaling, our analysis highlights several unchartered regions of SnRK1 signaling in plants such as its possible communication with chromatin remodelers, histone modifiers, and inositol phosphate signaling. We also discuss potential reciprocal interactions of SnRK1 signaling with other signaling pathways and cellular processes, which could be involved in maintaining flexibility and homeostasis under different environmental conditions. Overall, this review provides a comprehensive overview of the SnRK1 signaling network in plants and suggests many novel directions for future research. 

The present study investigated the efficiency of CRISPR/Cas9 in creating genomic deletions as the basis of its application in removing selection marker genes or the intergenic regions. Three loci, representing a transgene and two rice genes, were targeted at two sites each, in separate experiments, and the deletion of the defined fragments was investigated by PCR and sequencing. Genomic deletions were found at a low rate among the transformed callus lines that could be isolated, cultured, and regenerated into plants harboring the deletion. However, randomly regenerated plants showed mixed genomic effects, and generally did not harbor heritable genomic deletions. To determine whether point mutations occurred at each targeted site, a total of 114 plants consisting of primary transgenic lines and their progeny were analyzed. Ninety-three plants showed targeting, 60 of which were targeted at both sites. The presence of point mutations at both sites was correlated with the guide RNA efficiency. In summary, genomic deletions through dual-targeting by the paired-guide RNAs were generally observed in callus, while de novo point mutations at one or both sites occurred at high rates in transgenic plants and their progeny, generating a variety of insertion–deletions or single-nucleotide variations. In this study, point mutations were exceedingly favored over genomic deletions; therefore, for the recovery of plant lines harboring targeted deletions, identifying early transformed clones harboring the deletions, and isolating them for plant regeneration is recommended. 

SUMMARY Grain chalkiness is a major concern in rice production because it impacts milling yield and cooking quality, eventually reducing market value of the rice. A gene encoding vacuolar H⁺translocating pyrophosphatase (V‐PPase) is a major quantitative trait locus inindicarice, controlling grain chalkiness. Higher transcriptional activity of this gene is associated with increased chalk content. However, whether the suppression ofV‐PPasecould reduce chalkiness is not clear. Furthermore, natural variation in the chalkiness ofjaponicarice has not been linked withV‐PPase. Here, we describe promoter targeting of thejaponica V‐PPaseallele that led to reduced grain chalkiness and the development of more translucent grains. Disruption of a putative GATA element by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR‐associated protein 9 suppressedV‐PPaseactivity, reduced grain chalkiness and impacted post‐germination growth that could be rescued by the exogenous supply of sucrose. The mature grains of the targeted lines showed a much lower percentage of large or medium chalk. Interestingly, the targeted lines developed a significantly lower chalk under heat stress, a major inducer of grain chalk. Metabolomic analysis showed that pathways related to starch and sugar metabolism were affected in the developing grains of the targeted lines that correlated with higher inorganic pyrophosphate and starch contents and upregulation of starch biosynthesis genes. In summary, we show a biotechnology approach of reducing grain chalkiness in rice by downregulating the transcriptional activity ofV‐PPasethat presumably leads to altered metabolic rates, including starch biosynthesis, resulting in more compact packing of starch granules and formation of translucent rice grains.