Plant Direct最新文献

Because of the detrimental effects of terrestrial invasive plant species (TIPS) on native species, ecosystems, public health, and the economy, many countries have been actively looking for strategies to prevent the introduction and minimize the spread of TIPS. Fast and accurate detection of TIPS is essential to achieving these goals. Conventionally, invasive species monitoring has relied on morphological attributes. Recently, DNA-based species identification (i.e., DNA barcoding) has become more attractive. To investigate whether DNA barcoding can aid in the detection and management of TIPS, we visited multiple nature areas in Southwest Michigan and collected a small piece of leaf tissue from 91 representative terrestrial plant species, most of which are invasive. We extracted DNA from the leaf samples, amplified four genomic loci (ITS, rbcL, matK, and trnH-psbA) with PCR, and then purified and sequenced the PCR products. After careful examination of the sequencing data, we were able to identify reliable DNA barcode regions for most species and had an average PCR-and-sequencing success rate of 87.9%. We found that the species discrimination rate of a DNA barcode region is inversely related to the ease of PCR amplification and sequencing. Compared with rbcL and matK, ITS and trnH-psbA have better species discrimination rates (80.6% and 63.2%, respectively). When ITS and trnH-psbA are simultaneously used, the species discrimination rate increases to 97.1%. The high species/genus/family discrimination rates of DNA barcoding indicate that DNA barcoding can be successfully employed in TIPS identification. Further increases in the number of DNA barcode regions show little or no additional increases in the species discrimination rate, suggesting that dual-barcode approaches (e.g., ITS + trnH-psbA) might be the efficient and cost-effective method in DNA-based TIPS identification. Close inspection of nucleotide sequences at the four DNA barcode regions among related species demonstrates that DNA barcoding is especially useful in identifying TIPS that are morphologically similar to other species.

Rice genetic diversity is regulated by multiple genes and is largely dependent on various environmental factors. Uncovering the genetic variations associated with the diversity in rice populations is the key to breed stable and high yielding rice varieties. We performed genome wide association studies (GWASs) on seven rice yielding traits (grain length, grain width, grain weight, panicle length, leaf length, leaf width, and leaf angle) based on a population of 183 rice landraces of Bangladesh. Our GWASs reveal various chromosomal regions and candidate genes that are associated with different traits in Bangladeshi rice varieties. Noteworthy was the recurrent implication of chromosome 10 in all three grain-shape-related traits (grain length, grain width, and grain weight), indicating its pivotal role in shaping rice grain morphology. Our study also underscores the involvement of transposon gene families across these three traits. For leaf related traits, chromosome 10 was found to harbor regions that are significantly associated with leaf length and leaf width. The results of these association studies support previous findings as well as provide additional insights into the genetic diversity of rice. This is the first known GWAS study on various yield-related traits in the varieties of Oryza sativa available in Bangladesh-the fourth largest rice-producing country. We believe this study will accelerate rice genetics research and breeding stable high-yielding rice in Bangladesh.

Eukaryotic cells are highly compartmentalized, requiring elaborate transport mechanisms to facilitate the movement of proteins between membrane-bound compartments. Most proteins synthesized in the endoplasmic reticulum (ER) are transported to the Golgi apparatus through COPII-mediated vesicular trafficking. Sar1, a small GTPase that facilitates the formation of COPII vesicles, plays a critical role in the early steps of this protein secretory pathway. Sar1 was characterized in yeast, animals and plants, but no Sar1 homolog has been identified and functionally analyzed in algae. Here we identified a putative Sar1 homolog (CrSar1) in the model green alga Chlamydomonas reinhardtii through amino acid sequence similarity. We employed site-directed mutagenesis to generate a dominant-negative mutant of CrSar1 (CrSar1DN). Using protein secretion assays, we demonstrate the inhibitory effect of CrSar1DN on protein secretion. However, different from previously studied organisms, ectopic expression of CrSar1DN did not result in collapse of the ER-Golgi interface in Chlamydomonas. Nonetheless, our data suggest a largely conserved role of CrSar1 in the ER-to-Golgi protein secretory pathway in green algae.

Exocytosis plays an essential role in delivering proteins, lipids, and cell wall polysaccharides to the plasma membrane and extracellular spaces. Accurate secretion through exocytosis is key to normal plant development as well as responses to biotic and abiotic stresses. During exocytosis, an octameric protein complex named the exocyst facilitates the tethering of secretory vesicles to the plasma membrane. Despite some understanding of molecular and cellular aspects of exocyst function obtained through reverse genetics and direct interaction assays, knowledge about upstream modulators and genetic interactors remains limited. Traditional genetic screens encounter practical issues in exocyst subunit mutant backgrounds, such as lethality of certain knockout mutants and/or potential redundancy of EXO70 homologs. To address these challenges, this study leverages the tunable and reversible nature of chemical genetics, employing Endosidin2 (ES2)-a synthetic inhibitor of EXO70-for a large-scale chemical genetic mutant screen in Arabidopsis. This approach led to the identification of 70 ES2-hypersensitive mutants, named es2s. Through a whole-genome sequencing-based mapping strategy, 14 nonallelic es2s mutants were mapped and the candidate mutations reported here. In addition, T-DNA insertion lines were tested as alternative alleles to identify causal mutations. We found that T-DNA insertion alleles for DCP5, VAS1/ISS1, ArgJ, and MEF11 were hypersensitive to ES2 for root growth inhibition. This research not only offers new genetic resources for systematically identifying molecular players interacting with the exocyst in Arabidopsis but also enhances understanding of the regulation of exocytosis.

Comparative measurements of four Vitis vinifera cultivars were undertaken to assess assimilation tolerance to the high growth temperatures currently pervading Australian and other wine growing regions. The cultivars, cvs. Chardonnay, Merlot, Semillon, and Shiraz, were all grown in common growth conditions, and an hypothesis promulgated genotypic variation in assimilation and in the leaf temperature dependency. Assimilation responses to varying light intensity and to varying chloroplast CO₂ at a range of leaf temperatures (15-45°C) were measured in leaves of each cultivar in mid-summer. Light response curves revealed marked genotype differences in maximum assimilation, but temperature effects also varied. Semillon leaves were most sensitive to temperature, with marked and steep differences in assimilation at different temperatures while Chardonnay and Merlot were least sensitive, with relatively flat responses. There were also marked cultivar differences in response to CO₂ and significant effects of leaf temperature. CO₂-saturated assimilation varied markedly, with Semillon and Merlot leaves most responsive to temperature, although there were differences in optimum temperatures and maximum rates. Chardonnay leaves remained least tolerant, with lowest rates of assimilation across most temperatures. Assimilation at 45°C also separated the cultivars and two cultivars had higher rates than at 15°C while Chardonnay and Merlot leaves had higher rates at 15°C. There were no cultivar differences in the temperature dependency of Ribulose 1,5-bisphosphate (RuBP) carboxylation, but Semillon had a much steeper temperature dependency on RuBP regeneration than the other cultivars. All these responses confirmed the hypothesis and concluded the high-temperature tolerance of Semillon and Shiraz and the poor adaptability of Chardonnay and possibly Merlot to perform in the current high-temperature growth conditions.

Agrobacterium-mediated transient expression methods are widely used to study gene function in both model and non-model plants. Using a dual-luciferase assay, we quantified the effect of Agrobacterium-infiltration parameters on the transient transformation efficiency of Catharanthus roseus seedlings. We showed that transformation efficiency is highly sensitive to seedling developmental state and a pre- and post-infiltration dark incubation and is less sensitive to the Agrobacterium growth stage. For example, 5 versus 6 days of germination in the dark increased seedling transformation efficiency by seven- to eight-fold while a dark incubation pre- and post-infiltration increased transformation efficiency by five- to 13-fold. Agrobacterium in exponential compared with stationary phase increased transformation efficiency by two-fold. Finally, we quantified the variation in our Agrobacterium-infiltration method in replicate infiltrations and experiments. Within a given experiment, significant differences of up to 2.6-fold in raw firefly luciferase (FLUC) and raw Renilla luciferase (RLUC) luminescence occurred in replicate infiltrations. These differences were significantly reduced when FLUC was normalized to RLUC values, highlighting the utility of including a reference reporter to minimize false positives. Including a second experimental replicate further reduced the potential for false positives. This optimization and quantitative validation of Agrobacterium infiltration in C. roseus seedlings will facilitate the study of this important medicinal plant and will expand the application of Agrobacterium-mediated transformation methods in other plant species.

To investigate the molecular mechanism of the defense response of "Cabernet Sauvignon" grapes to feeding by Apolygus lucorum, high-throughput sequencing technology was used to analyze the transcriptome of grape leaves under three different treatments: feeding by A. lucorum, puncture injury, and an untreated control. The research findings indicated that the differentially expressed genes were primarily enriched in three aspects: cellular composition, molecular function, and biological process. These genes were found to be involved in 42 metabolic pathways, particularly in plant hormone signaling metabolism, plant-pathogen interaction, MAPK signaling pathway, and other metabolic pathways associated with plant-induced insect resistance. Feeding by A. lucorum stimulated and upregulated a significant number of genes related to jasmonic acid and calcium ion pathways, suggesting their crucial role in the defense molecular mechanism of "Cabernet Sauvignon" grapes. The consistency between the gene expression and transcriptome sequencing results further supports these findings. This study provides a reference for the further exploration of the defense response in "Cabernet Sauvignon" grapes by elucidating the expression of relevant genes during feeding by A. lucorum.