Boosting crop yields with plant steroids

Plant sterols and steroid hormones, the brassinosteroids (BRs), are compounds that exert a wide range of biological activities. They are essential for plant growth, reproduction, and responses to various abiotic and biotic stresses. Given the importance of sterols and BRs in these processes, engineering their biosynthetic and signaling pathways offers exciting potentials for enhancing crop yield. In this review, we focus on how alterations in components of sterol and BR metabolism and signaling or application of exogenous steroids and steroid inhibitors affect traits of agronomic importance. We also discuss areas for future research and identify the fine-tuning modulation of endogenous BR content as a promising strategy for crop improvement

Stress-induced chromatin changes in plants: of memories, metabolites and crop improvement

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From squalene to brassinolide : the steroid metabolic and signaling pathways across the plant kingdom

The plant steroid hormones, brassinosteroids, and their precursors, phytosterols, are essential for plant growth, reproduction, and response to various abiotic and biotic stresses. We review their biological activities and discuss recent advances in elucidating their metabolism, transport, and signaling pathways.The plant steroid hormones, brassinosteroids (BRs), and their precursors, phytosterols, play major roles in plant growth, development, and stress tolerance. Here, we review the impressive progress made during recent years in elucidating the components of the sterol and BR metabolic and signaling pathways, and in understanding their mechanism of action in both model plants and crops, such as Arabidopsis and rice. We also discuss emerging insights into the regulations of these pathways, their interactions with other hormonal pathways and multiple environmental signals, and the putative nature of sterols as signaling molecules

Evolutionary trails of plant steroid genes

Plant steroids - brassinosteroids (BRs) and their precursors, phytosterols-play a major role in plant growth, development, stress tolerance, and have high potential for agricultural applications. Currently, this prospect is limited by a lack of information about their evolution and expression dynamics (spatial and temporal) across plant species. The increasing number of sequenced genomes offers an opportunity for evolutionary studies that might help to prioritize functional analyses with the aim to improve crop yield and stress tolerance. In this review we provide a glimpse of the origin, evolution, and functional conservation of phytosterol and BR genes in the green plant lineage using comparative sequence and expression analyses of publicly available datasets

Root Starch Reserves Are Necessary for Vigorous Re-Growth following Cutting Back in <i>Lotus japonicus</i>

<div><p>Perenniality and vegetative re-growth vigour represent key agronomic traits in forage legume (Fabaceae) species. The known determinants of perenniality include the conservation of the vegetative meristem during and after the flowering phase, and the separation of flowering from senescence. The ability of the plants to store nutrient resources in perennial organs and remobilize them may also play an important role in the perennial growth habit, and in determining the capacity of the plant to re-grow following grazing or from one season to the next. To examine the importance of stored starch, we examined the vegetative re-growth vigour following cutting back of a unique collection of <i>Lotus japonicus</i> mutants impaired in their ability to synthesize or degrade starch. Our results establish that starch stored in the roots is important for re-growth vigour in <i>Lotus japonicus.</i> We extended this analysis to a collection of <i>Lotus</i> (trefoil) species and two ecotypes of <i>Lotus japonicus</i> displaying a large variation in their carbohydrate resource allocation. There was a positive correlation between root starch content and re-growth vigour in these natural variants, and a good general correlation between high re-growth vigour and the perennial life-form. We discuss the relationship between perenniality and the availability of root carbohydrates for re-growth.</p></div

Transcriptional regulation of plant sugar transporter genes by beneficial rhizobacteria

In their natural environment, plants live in close interaction with complex populations of microorganisms, including rhizobacteria species commonly referred to as ‘Plant Growth Promoting Rhizobacteria’ (PGPR). A growing body of evidence demonstrates the importance of sugar transport in plant pathogen resistance and in plant-microorganism mutualistic symbioses. Using an in vitro experimental system, including the model plant species Arabidopsis thaliana, two PGPR strains (Pseudomonas simiae PICF7 and Burkholderia phytofirmans PsJN) and a non-PGPR strain (Escherichia coli), we conducted a comprehensive set of phenotypic and gene expression analyses to explore the role and regulation of sugar transporter genes in plant-PGPR interactions. In physical contact with the seedling roots, or solely via the emission of bacterial volatile compounds, the two PGPR strains tested improved the growth and development of the Arabidopsis seedlings and altered the expression of several plant sugar transporter genes. Our results also revealed both conserved and strain-specific transcriptional regulation mechanisms.This work was funded by the French Ministry of Higher Education, Research and Innovation (“Ministère de l’Enseignement supérieur, de la Recherche et de l’Innovation”) (AD, PhD grant), the 2015-2020 State Region Planning Contracts (CPER), the European Regional Development Fund (FEDER), and intramural funds from the French National Centre for Scientific Research (“Centre National de la Recherche Scientifique”) and the University of Poitiers

Re-growth after cutting back of a collection of <i>Lotus</i> species.

<p>Plants were grown in the glasshouse and analyses performed on four to five month old plants, as for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087333#pone-0087333-g002" target="_blank">Figure 2</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087333#pone-0087333-g003" target="_blank">Figure 3</a>. Plants in the first batch were grown in a glasshouse supplemented with artificial light (photoperiod of 16 h). Plants in the second were grown in a glasshouse under natural long days. Values are means ± SE of measurements on the number of plants indicated (n), 15 days after cutting back. n.d. – not determined; FW – fresh weight. Sources for the “USDA/GRIN and published life forms” are as follows: Germplasm Resource Information Network (GRIN, <a href="http://www.ars-grin.gov/" target="_blank">http://www.ars-grin.gov/</a>) database; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087333#pone.0087333-Handberg1" target="_blank">[9]</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087333#pone.0087333-Kawaguchi1" target="_blank">[10]</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087333#pone.0087333-SzBoros1" target="_blank">[11]</a>.</p

Effect of cutting back on growth of <i>L. japonicus</i> starch mutants.

<p>Plants of <i>pgm1-1</i>, <i>pgm1-4</i>, <i>pgm1-5</i>, <i>apl1-1, aps1-1</i>, <i>gwd1-1</i>, and <i>gwd1-3</i> and their wild-type (WT) segregants were grown in a glasshouse, supplemented with artificial light to provide long days. Plants of <i>pgi1-1, apl1-1</i> and their wild-types were grown in a glasshouse under natural long days. All mutants were cut back when four- to five-months old, except for <i>apl1-1</i> and its WT segregants which were 10 months old. (A) Shoot fresh weight six weeks after cutting, as a percentage of shoot fresh weight at the time of cutting. Each mutant (white bar) is compared with co-segregating wild-type plants from the same population (black bar), except for <i>aps1-1</i> which is compared with the parental wild-type lines Gifu and MG-20 as no segregants were available. Values are means from the number of biological replicates indicated on each bar, ± SE. Values differed significantly between mutant and wild-type plants (Student’s t test, p<0.05) for <i>pgm1-4</i>, <i>pgm1-5</i>, and <i>aps1-1</i> mutants but not for other mutants. (B) Appearance of <i>pgm1-4</i> and wild-type plants after re-growth. (C) Appearance of root systems of representative mutant plants and a representative wild-type plant (PGM1-4 segregant) following decolourisation and iodine staining (samples representative of at least three biological replicates). Note the lack of iodine staining in <i>pgm1-4</i> and <i>aps1-1</i> root systems.</p