Deciphering the Molecular Mechanism of the Intermediate Secondary Growth and Internode Elongation of the Castor Bean (Ricinus communis L.) by the Combined Analysis of the Transcriptome and Metabolome.

The length of internodes plays a crucial role in determining the height of the castor plant (Ricinus communis L.). However, the specific mechanisms underlying internode elongation, particularly in the main stem of the castor plant, remain uncertain. To further investigate this, we conducted a study focusing on the internode tissue of the dwarf castor variety 071113, comparing it with the control high-stalk Zhuansihao. Our study included a cytological observation, physiological measurement, transcriptome sequencing, and metabolic determination. Our integrated findings reveal that the dwarf variety 071113 undergoes an earlier lignification development in the main stem and has a more active lignin synthesis pathway during internode intermediate development. In addition, the dwarf variety exhibited lower levels of the plant hormone indole-3-acetic acid (IAA), which had an impact on the development process. Furthermore, we identified specific enzymes and regulators that were enriched in the pathways of the cell cycle, auxin signal transduction, and secondary cell wall synthesis. Using these findings, we developed a model that explained the intermediate secondary growth observed in castor internode elongation and enhanced our comprehension of the dwarfing mechanism of the 071113 variety. This research provides a theoretical groundwork for the future breeding of dwarf castor varieties.

Evaluation of phosphate rock as the only source of phosphorus for the growth of tall and semi-dwarf durum wheat and rye plants using digital phenotyping.

Background: Phosphorus nutrition is important for obtaining high yields of crop plants. However, wheat plants are known to be almost incapable of taking up phosphorus from insoluble phosphate sources, and reduced height genes are supposed to decrease this ability further. Methods: We performed a pot experiment using Triticum durum Desf. tall spring variety LD222, its near-isogenic semidwarf line carrying Rht17 (Reduced height 17) gene, and winter rye (Secale cereale L.) variety Chulpan. The individual plants were grown in quartz sand. The phosphorus was provided either as phosphate rock powder mixed with sand, or as monopotassium phosphate solution (normal nutrition control) or was not supplemented at all (no-phosphorus control). Other nutrients were provided in soluble form. During experiment the plants were assessed using the TraitFinder (Phenospex Ltd., Heerlen, Netherlands) digital phenotyping system for a standard set of parameters. Double scan with 90 degrees turns of pots around vertical axis vs. single scan were compared for accuracy of phenotyping. Results: The phenotyping showed that at least 20 days of growth after seedling emergence were necessary to get stable differences between genotypes. After this initial period, phenotyping confirmed poor ability of wheat to grow on substrate with phosphate rock as the only source of phosphorus compared to rye; however, Rht17 did not cause an additional reduction in growth parameters other than plant height under this variant of substrate. The agreement between digital phenotyping and conventionally measured traits was at previously reported level for grasses (R2 = 0.85 and 0.88 for digital biomass and 3D leaf area vs. conventionally measured biomass and leaf area, single scan). Among vegetation indices, only the normalized differential vegetation index (NDVI) and the green leaf index (GLI) showed significant correlations with manually measured traits, including the percentage of dead leaves area. The double scan improved phenotyping accuracy, but not substantially.

Insights into the Genetic Determination of the Autotetraploid Potato Plant Height.

Plant height is an important characteristic, the modification of which can improve the ability of stress adaptation as well as the yield. In this study, genome-wide association analysis was performed for plant height traits in 370 potato cultivars using the tetraploid potato genome as a reference. A total of 92 significant single nucleotide polymorphism (SNP) loci for plant height were obtained, which were particularly significant in haplotypes A3 and A4 on chromosome 1 and A1, A2, and A4 on chromosome 5. Thirty-five candidate genes were identified that were mainly involved in the gibberellin and brassinolide signal transduction pathways, including the FAR1 gene, methyltransferase, ethylene response factor, and ubiquitin protein ligase. Among them, PIF3 and GID1a were only present on chromosome 1, with PIF3 in all four haplotypes and GID1a in haplotype A3. This could lead to more effective genetic loci for molecular marker-assisted selection breeding as well as more precise localization and cloning of genes for plant height traits in potatoes.

Genome-wide association study dissects the genetic control of plant height and branch number in response to low-phosphorus stress in Brassica napus.

BACKGROUND AND AIMS: Oilseed rape (Brassica napus) is one of the most important oil crops worldwide. Phosphorus (P) deficiency severely decreases the plant height and branch number of B. napus. However, the genetic bases controlling plant height and branch number in B. napus under P deficiency remain largely unknown. This study aims to mine candidate genes for plant height and branch number by genome-wide association study (GWAS) and determine low-P-tolerance haplotypes. METHODS: An association panel of B. napus was grown in the field with a low P supply (P, 0 kg ha-1) and a sufficient P supply (P, 40 kg ha-1) across 2 years and plant height and branch number were investigated. More than five million single-nucleotide polymorphisms (SNPs) were used to conduct GWAS of plant height and branch number at two contrasting P supplies. KEY RESULTS: A total of 2127 SNPs were strongly associated (P < 6·25 × 10-07) with plant height and branch number at two P supplies. There was significant correlation between phenotypic variation and the number of favourable alleles of associated loci on chromosomes A10 (chrA10_821671) and C08 (chrC08_27999846), which will contribute to breeding improvement by aggregating these SNPs. BnaA10g09290D and BnaC08g26640D were identified to be associated with chrA10_821671 and chrC08_27999846, respectively. Candidate gene association analysis and haplotype analysis showed that the inbred lines carrying ATT at BnaA10g09290Hap1 and AAT at BnaC08g26640Hap1 had greater plant height than lines carrying other haplotype alleles at low P supply. CONCLUSION: Our results demonstrate the power of GWAS in identifying genes of interest in B. napus and provided insights into the genetic basis of plant height and branch number at low P supply in B. napus. Candidate genes and favourable haplotypes may facilitate marker-based breeding efforts aimed at improving P use efficiency in B. napus.

Transcriptome dynamic landscape underlying the improvement of maize lodging resistance under coronatine treatment.

BACKGROUND: Lodging is one of the important factors causing maize yield. Plant height is an important factor in determining plant architecture in maize (Zea mays L.), which is closely related to lodging resistance under high planting density. Coronatine (COR), which is a phytotoxin and produced by the pathogen Pseudomonas syringae, is a functional and structural analogue of jasmonic acid (JA). RESULTS: In this study, we found COR, as a new plant growth regulator, could effectively reduce plant height and ear height of both hybrids (ZD958 and XY335) and inbred (B73) maize by inhibiting internode growth during elongation, thus improve maize lodging resistance. To study gene expression changes in internode after COR treatment, we collected spatio-temporal transcriptome of inbred B73 internode under normal condition and COR treatment, including the three different regions of internode (fixed, meristem and elongation regions) at three different developmental stages. The gene expression levels of the three regions at normal condition were described and then compared with that upon COR treatment. In total, 8605 COR-responsive genes (COR-RGs) were found, consist of 802 genes specifically expressed in internode. For these COR-RGs, 614, 870, 2123 of which showed expression changes in only fixed, meristem and elongation region, respectively. Both the number and function were significantly changed for COR-RGs identified in different regions, indicating genes with different functions were regulated at the three regions. Besides, we found more than 80% genes of gibberellin and jasmonic acid were changed under COR treatment. CONCLUSIONS: These data provide a gene expression profiling in different regions of internode development and molecular mechanism of COR affecting internode elongation. A putative schematic of the internode response to COR treatment is proposed which shows the basic process of COR affecting internode elongation. This research provides a useful resource for studying maize internode development and improves our understanding of the COR regulation mechanism based on plant height.

A GPAT1 Mutation in Arabidopsis Enhances Plant Height but Impairs Seed Oil Biosynthesis.

Glycerol-3-phosphate acyltransferases (GPATs) play an important role in glycerolipid biosynthesis, and are mainly involved in oil production, flower development, and stress response. However, their roles in regulating plant height remain unreported. Here, we report that Arabidopsis GPAT1 is involved in the regulation of plant height. GUS assay and qRT-PCR analysis in Arabidopsis showed that GPAT1 is highly expressed in flowers, siliques, and seeds. A loss of function mutation in GPAT1 was shown to decrease seed yield but increase plant height through enhanced cell length. Transcriptomic and qRT-PCR data revealed that the expression levels of genes related to gibberellin (GA) biosynthesis and signaling, as well as those of cell wall organization and biogenesis, were significantly upregulated. These led to cell length elongation, and thus, an increase in plant height. Together, our data suggest that knockout of GPAT1 impairs glycerolipid metabolism in Arabidopsis, leading to reduced seed yield, but promotes the biosynthesis of GA, which ultimately enhances plant height. This study provides new evidence on the interplay between lipid and hormone metabolism in the regulation of plant height.

Evaluation of Growth Performances of Some Locally Farmed Maize (Zea mays L.) in Cross River State, Nigeria under Different Concentrations of Silicon.

OBJECTIVE: Growth performances of four maize varieties (91 SUWANI, TZL COMP 4, DT STR Y SYN 2 and IWO SYN C2) were investigated at four levels of silicon concentration (0, 2500, 5000 and 7500 mg, with 0 mg as control). METHODOLOGY: Viable seeds were planted in polythene bags (64 bags) containing soil in a randomized complete block design (a 4×4 factorial experiment) with four replications. Plant height, stem girth, leaf area and leaf number were evaluated at 4, 6, 8 and 10 weeks after planting. RESULTS: There was significant difference (p≤0.05) for all growth parameters and across varieties. Highest mean plant height (144.58 cm) and mean number of leaves (12.23) were recorded at 5000 mg silicon concentration in all varieties, while stem girth and stem biomass were highest in TZL COMP4 (3.42 cm, 38.44 dry weight g-1). CONCLUSION: Based on these results, 5000 mg silicon concentration is recommended as nutrient supplement to enhance maize production.

Ecotype variability in growth and secondary metabolite profile in Moringa oleifera: impact of sulfur and water availability.

Moringa oleifera is widely cultivated in plantations in the tropics and subtropics. Previous cultivation studies with M. oleifera focused primarily only on leaf yield. In the present study, the content of potentially health-promoting secondary metabolites (glucosinolates, phenolic acids, and flavonoids) were also investigated. Six different ecotypes were grown under similar environmental conditions to identify phenotypic differences that can be traced back to the genotype. The ecotypes TOT4880 (origin USA) and TOT7267 (origin India) were identified as having the best growth performance and highest secondary metabolite production, making them an ideal health-promoting food crop. Furthermore, optimal cultivation conditions-exemplarily on sulfur fertilization and water availability-for achieving high leaf and secondary metabolite yields were investigated for M. oleifera. In general, plant biomass and height decreased under water deficiency compared to normal cultivation conditions, whereas the glucosinolate content increased. The effects depended to a great extent on the ecotype.

Stem extension and mechanical stability of Xanthium canadense grown in an open or in a dense stand.

BACKGROUND AND AIMS: Plants in open, uncrowded habitats typically have relatively short stems with many branches, whereas plants in crowded habitats grow taller and more slender at the expense of mechanical stability. There seems to be a trade-off between height growth and mechanical stability, and this study addresses how stand density influences stem extension and consequently plant safety margins against mechanical failure. METHODS: Xanthium canadense plants were grown either solitarily (S-plants) or in a dense stand (D-plants) until flowering. Internode dimensions and mechanical properties were measured at the metamer level, and the critical buckling height beyond which the plant elastically buckles under its own weight and the maximum lateral wind force the plant can withstand were calculated. KEY RESULTS: Internodes were longer in D- than S-plants, but basal diameter did not differ significantly. Relative growth rates of internode length and diameter were negatively correlated to the volumetric solid fraction of the internode. Internode dry mass density was higher in S- than D-plants. Young's modulus of elasticity and the breaking stress were higher in lower metamers, and in D- than in S-plants. Within a stand, however, both moduli were positively related to dry mass density. The buckling safety factor, a ratio of critical buckling height to actual height, was higher in S- than in D-plants. D-plants were found to be approaching the limiting value 1. Lateral wind force resistance was higher in S- than in D-plants, and increased with growth in S-plants. CONCLUSIONS: Critical buckling height increased with height growth due mainly to an increase in stem stiffness and diameter and a reduction in crown/stem mass ratio. Lateral wind force resistance was enhanced due to increased tissue strength and diameter. The increase in tissue stiffness and strength with height growth plays a crucial role in maintaining a safety margin against mechanical failure in herbaceous species that lack the capacity for secondary growth.

Plant growth regulator losses in cotton as affected by adjuvants and rain / Perdas de reguladores de crescimento do algodoeiro em função de adjuvante e de chuva simulada

Most of Brazilian cotton is produced in regions where annual rainfall exceeds 1,500mm, hence plant growth regulators (PGR) may be washed from the leaves before being absorbed. The objective of this research was to evaluate mepiquat chloride and chlormequat chloride washing from cotton leaves by rains occurring at different moments post spraying. The experiment was conducted in a greenhouse. Both PGR were sprayed to cotton at pin-head square at 15g ha-1 a.i. with and without a silicon-based adjuvant, and simulated rains were applied at 0, 0.75, 1.5, 3.0, 6.0, 12.0 and 24 hours after spraying, plus a control without rainfall. Addition of silicon adjuvant increased PGR uptake. Rainfall occurring up to 24 hours after spraying resulted in some PGR loss from cotton leaves, mainly in the absence of the adjuvant. The decreased uptake implies that in order to achieve the desired level of growth reduction, at least a fraction of the original PGR rate should be reapplied.

Nas maiores regiões algodoeiras no Brasil, chove mais de 1.500mm anuais, existindo risco de ocorrer lavagem de reguladores de crescimento aplicados às folhas do algodoeiro, antes que sejam absorvidos. O objetivo deste trabalho foi avaliar a lavagem dos reguladores de crescimento cloreto de mepiquat e cloreto de chlormequat de folhas de algodoeiro por chuva, ocorrendo em diferentes momentos após a aplicação. O trabalho foi realizado em casa de vegetação. Ambos os reguladores foram aplicados no aparecimento do primeiro botão floral, na dose de 15g ha-1 de i.a. com e sem adjuvante siliconado, e chuva simulada foi aplicada aos 0, 0,75; 1,5; 3,0; 6,0; 12,0 e 24 horas após a aplicação dos reguladores, mais um tratamento sem chuva. A adição de adjuvante siliconado melhorou a absorção dos produtos. A ocorrência de chuva até mesmo 24 horas após a aplicação dos reguladores pode lavar parte dos produtos das plantas de algodoeiro, com maior intensidade para o tratamento sem adjuvante. A redução da absorção do produto leva à necessidade de reaplicá-lo para que possa haver a sua ação, sem comprometer sua função.

Aplicação foliar de manganês em soja transgênica tolerante ao glyphosate / Foliar application of manganese in transgenic soybean tolerant to glyphosate

O amarelecimento da soja Roundup Ready após aplicação do glyphosate pode estar associado à deficiência momentânea de manganês. Por isso, com a hipótese de que soja tolerante ao glyphosate necessitaria de uma adição suplementar de manganês, o objetivo deste trabalho foi avaliar diferentes manejos na aplicação foliar de manganês sobre alguns parâmetros da soja. Foram desenvolvidos dois experimentos, um no município de Taquaruçú do Sul e outro em Boa Vista das Missões, RS, no ano agrícola 2009/2010. Foram testados os seguintes tratamentos: 1) sem aplicação de glyphosate, com controle manual das plantas daninhas e sem aplicação foliar de manganês (testemunha); 2) sem aplicação de glyphosate, com controle manual das plantas daninhas e uma aplicação foliar de manganês sete dias após esse controle manual das plantas daninhas; 3) com aplicação de glyphosate e sem aplicação foliar de manganês; 4) aplicação de glyphosate em mistura com manganês; 5) aplicação de glyphosate mais uma aplicação foliar de manganês sete dias após aplicação do glyphosate; 6) aplicação de glyphosate mais aplicação foliar de manganês parcelada em duas épocas, aos 7 e 14 dias após aplicação do glyphosate; 7) aplicação de glyphosate e uma aplicação foliar de manganês aos 14 dias após aplicação de glyphosate. A aplicação de glyphosate foi realizada no estádio V5 da soja, na dose de 720g L-1 e.a, enquanto a dose de Mn utilizada foi 2,0L ha-1 de uma formulação contendo 14 por cento (m/v) de manganês solúvel. Não houve diferença significativa entre os tratamentos para as variáveis estatura de plantas e altura de inserção da primeira vagem. A aplicação de glyphosate não afetou a absorção e o teor foliar de manganês e nitrogênio na cultura da soja. Mesmo com aumento no teor foliar de manganês com a suplementação de manganês, não houve incremento na produtividade da soja. Isso mostra que em solos com teores de Mn acima do suficiente a aplicação do herbicida glifosato não requer a suplementação foliar de manganês em soja geneticamente modificada tolerante a esse herbicida.

The yellowing of Roundup Ready soybean after glyphosate application, can be associated to a momentary manganese deficiency. Because of that, with the hypothesis that glyphosate tolerant soybean would need supplementary addition of manganese, the objective of this research was to evaluate different managements in the foliar application of manganese in some soybean parameters. It was developed two experiments, one at Taquaruçú do Sul and other at Boa Vista das Missões, RS in the year of 2009/2010. It was tested the following treatments: 1) without glyphosate application with manual weed control and without manganese foliar application (untreated check); 2) without glyphosate application with manual weed control and one manganese foliar application at 7 days after this manual weed control; 3) with glyphosate application and without manganese foliar application; 4) glyphosate application in mixture with manganese; 5) glyphosate application added of one manganese foliar application at 7 days after glyphosate application; 6) glyphosate application added of manganese foliar application split in two times, at 7 and 14 days after glyphosate application; 7) glyphosate application and one of manganese foliar application at 14 days after glyphosate application. The glyphosate application was realized in the V5 soybean stage, using 720g L-1 i.e, while the used dose of Mn was 2.0L ha-1 of a formulation with 14 percent (m/v) of Mn. There were no significant difference among the treatments to plant height and height insertion of the first legume. The glyphosate application did not affect the absorption and the foliar amount of manganese and nitrogen in soybean crop. Even with the increase in foliar manganese amount, there was no increasing in soybean productivity. This shows that in soils with Mn levels above of the sufficient, it is not necessary foliar manganese addition in genetically modified soybean tolerant to glyphosate.