Gene pyramiding improved cell membrane stability under heat stress in cotton (Gossypium hirsutum L.).

Climate change has been drastically affecting cotton not only in Pakistan but also all over the world. Normally cotton is known as heat tolerant when compared with other crops, but if the high temperature occurs during flowering period the yield decreases significantly. Marker assisted gene pyramiding provides a sustainable solution to improve heat tolerance. A total of seven genotypes were developed by a series of crossing seven tolerant genotypes over the period of three years. Tolerant genotypes were selected by screening for important transcription factors (GHSP26, HSP3, HSFA2, DREB1A, HSP101, DREB2A, GhNAC2, HSPCB, GhWRKY41, TPS, GbMYB5, ANNAT8, GhMPK17, GhMKK1, GhMKK3, GhMPK2, HSC70, APX1 and GhPP2A1). The seven genotypes were evaluated under normal and heat stress in a multi-year trial. The traits related to heat tolerance, such as cell membrane stability, relative water content, excised leaf water loss, plant height, number of nodes, internodal length, number of buds, number of bolls and leaf area was observed under normal and heat stress conditions. The developed genotypes showed improvement in cell membrane stability and relative water content under heat stress. The genotypes [(VH-305×MNH-886)×MNH-1035)×NIAB-78)], [(MNH-1035×MNH-886)×MNH-886)×SM-431] and [(MNH-1035×MNH-886)×MNH-886)×SS-32] depicted heat tolerance and could be used as heat tolerant material for variety development in breeding programs.

Sustaining rice productivity through weather-resilient agricultural practices.

BACKGROUND: Enhancing productivity and profitability and reducing climatic risk are the major challenges for sustaining rice production. Extreme weather can have significant and varied effects on crops, influencing agricultural productivity, crop yields and food security. RESULTS: In this study, a comparative evaluation of two crop management systems was performed involving farmers adopting a weather forecast-based advisory service (WFBAS) and usual farmers' practice (FP). WFBAS crop management followed the generated weather forecast-based advice whereas the control farmers (FP) did not receive any weather forecast-based advice, rather following their usual rice cultivation practices. The results of the experiments revealed that WFBAS farmers had a significant yield advantage over FP farmers. With the WFBAS technology, the farmers used inputs judiciously, utilized the benefit of favorable weather and minimized the risk resulting from extreme weather events. As a result, besides the yield enhancement, WFBAS provided a scope to protect the environment with the minimum residual effect of fertilizer and pesticides. It also reduced the pressure on groundwater by ensuring efficient water management. Finally, the farmers benefited from higher income through yield enhancement, reduction of the costs of production and reduction of risk. CONCLUSION: A successful and extensive implementation of WFBAS in the rice production system would assist Bangladesh in achieving Sustainable Development Goal 2.4, which focuses on rice productivity and profitability of farmers as well as long-term food security of the country. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

50 years of rice breeding in Bangladesh: genetic yield trends.

To assess the efficiency of genetic improvement programs, it is essential to assess the genetic trend in long-term data. The present study estimates the genetic trends for grain yield of rice varieties released between 1970 and 2020 by the Bangladesh Rice Research Institute. The yield of the varieties was assessed from 2001-2002 to 2020-2021 in multi-locations trials. In such a series of trials, yield may increase over time due to (i) genetic improvement (genetic trend) and (ii) improved management or favorable climate change (agronomic/non-genetic trend). In both the winter and monsoon seasons, we observed positive genetic and non-genetic trends. The annual genetic trend for grain yield in both winter and monsoon rice varieties was 0.01 t ha-1, while the non-genetic trend for both seasons was 0.02 t ha-1, corresponding to yearly genetic gains of 0.28% and 0.18% in winter and monsoon seasons, respectively. The overall percentage yield change from 1970 until 2020 for winter rice was 40.96%, of which 13.91% was genetic trend and 27.05% was non-genetic. For the monsoon season, the overall percentage change from 1973 until 2020 was 38.39%, of which genetic and non-genetic increases were 8.36% and 30.03%, respectively. Overall, the contribution of non-genetic trend is larger than genetic trend both for winter and monsoon seasons. These results suggest that limited progress has been made in improving yield in Bangladeshi rice breeding programs over the last 50 years. Breeding programs need to be modernized to deliver sufficient genetic gains in the future to sustain Bangladeshi food security.

Increasing floral visitation and hybrid seed production mediated by beauty mark in Gossypium hirsutum.

Hybrid crop varieties have been repeatedly demonstrated to produce significantly higher yields than their parental lines; however, the low efficiency and high cost of hybrid seed production has limited the broad exploitation of heterosis for cotton production. One option for increasing the yield of hybrid seed is to improve pollination efficiency by insect pollinators. Here, we report the molecular cloning and characterization of a semidominant gene, Beauty Mark (BM), which controls purple spot formation at the base of flower petals in the cultivated tetraploid cotton species Gossypium barbadense. BM encodes an R2R3 MYB113 transcription factor, and we demonstrate that GbBM directly targets the promoter of four flavonoid biosynthesis genes to positively regulate petal spot development. Introgression of a GbBM allele into G. hirsutum by marker-assisted selection restored petal spot formation, which significantly increased the frequency of honeybee visits in G. hirsutum. Moreover, field tests confirmed that cotton seed yield was significantly improved in a three-line hybrid production system that incorporated the GbBM allele. Our study thus provides a basis for the potentially broad application of this gene in improving the long-standing problem of low seed production in elite cotton hybrid lines.

Assessing the between-country genetic correlation in maize yield using German and Polish official variety trials.

KEY MESSAGE: We assess the genetic gain and genetic correlation in maize yield using German and Polish official variety trials. The random coefficient models were fitted to assess the genetic correlation. Official variety testing is performed in many countries by statutory agencies in order to identify the best candidates and make decisions on the addition to the national list. Neighbouring countries can have similarities in agroecological conditions, so it is worthwhile to consider a joint analysis of data from national list trials to assess the similarity in performance of those varieties tested in both countries. Here, maize yield data from official German and Poland variety trials for cultivation and use (VCU) were analysed for the period from 1987 to 2017. Several statistical models that incorporate environmental covariates were fitted. The best fitting model was used to compute estimates of genotype main effects for each country. It is demonstrated that a model with random genotype-by-country effects can be used to borrow strength across countries. The genetic correlation between cultivars from the two countries equalled 0.89. The analysis based on agroecological zones showed high correlation between zones in the two countries. The results also showed that 22 agroecological zones in Germany can be merged into five zones, whereas the six zones in Poland had very high correlation and can be considered as a single zone for maize. The 43 common varieties which were tested in both countries performed equally in both countries. The mean performances of these common varieties in both countries were highly correlated.

Comparative genetic, biochemical and physiological analysis of sodium and chlorine in wheat.

Plant with a great diversity shows several responses towards the biotic and abiotic stresses. Among these abiotic stresses, salinity is the main damaging factor as it reduces the yield of wheat plant with moderate salt tolerance. For its survival, plant undergoes through some genetic, biochemical and physiological changes to tackle the stress. This review mainly describes the conditions where various ions present in the soil, especially sodium and chlorine, enter into the plant and the genes or proteins involved with survival mechanism against the damage in plants. Salt stress causes alteration in enzymatic activity and Photosynthesis, oxidative stress, damage of cellular structure and components and ionic imbalance. Ion toxicity stress occur due to accumulation of excessive sodium ion and chloride ion. Transcriptional factors TaPIMP, TaSRG and TaMYBsdu 1 play key role in gene expression mechanism to overcome the stress. High affinity potassium transporter gene family is responsible for salt tolerance in wheat plant. HKT1;4 and HKT1;5 genes are responsible for Na exclusion in Triticum monococcum. Forty QTLs were found with the marker assisted selection in bread wheat for salinity tolerance and some morphological traits, 5 QTLs were related to sodium ion exclusion. In bread wheat, salt stress tolerance mechanism is mainly an exclusion of Na+ ions but also include K+ ion concentration. The salinity tolerant germplasm MW#293 provides an opportunity for the development of future salinity tolerant bread wheat.

Impact of heat stress responsive factors on growth and physiology of cotton (Gossypium hirsutum L.).

Pakistan ranked highest with reference to average temperatures in cotton growing areas of the world. The heat waves are becoming more intense and unpredictable due to climate change. Identification of heat tolerant genotypes requires comprehensive screening using molecular, physiological and morphological analysis. Heat shock proteins play an important role in tolerance against heat stress. In the current study, eight heat stress responsive factors, proteins and genes (HSFA2, GHSP26, GHPP2A, HSP101, HSC70-1, HSP3, APX1 and ANNAT8) were evaluated morphologically and physiologically for their role in heat stress tolerance. For this purpose, cotton crop was grown at two temperature conditions i.e. normal weather and heat stress at 45 °C. For molecular analysis, genotypes were screened for the presence or absence of heat shock protein genes. Physiological analysis of genotypes was conducted to assess net photosynthesis, stomatal conductance, transpiration rate, leaf-air temperature and cell membrane stability under control as well as high temperature. The traits photosynthesis, cell membrane stability, leaf-air temperature and number of heat stress responsive factors in each genotypes showed a strong correlation with boll retention percentage under heat stress. The genotypes with maximum heat shock protein genes such as Cyto-177, MNH-886, VH-305 and Cyto-515 showed increased photosynthesis, stomatal conductance, negative leaf-air temperature and high boll retention percentage under heat stress condition. These varieties may be used as heat tolerant breeding material.

Improved reconstruction and comparative analysis of chromosome 12 to rectify Mis-assemblies in Gossypium arboreum.

BACKGROUND: Genome sequencing technologies have been improved at an exponential pace but precise chromosome-scale genome assembly still remains a great challenge. The draft genome of cultivated G. arboreum was sequenced and assembled with shotgun sequencing approach, however, it contains several misassemblies. To address this issue, we generated an improved reassembly of G. arboreum chromosome 12 using genetic mapping and reference-assisted approaches and evaluated this reconstruction by comparing with homologous chromosomes of G. raimondii and G. hirsutum. RESULTS: In this study, we generated a high quality assembly of the 94.64 Mb length of G. arboreum chromosome 12 (A_A12) which comprised of 144 scaffolds and contained 3361 protein coding genes. Evaluation of results using syntenic and collinear analysis of reconstructed G. arboreum chromosome A_A12 with its homologous chromosomes of G. raimondii (D_D08) and G. hirsutum (AD_A12 and AD_D12) confirmed the significant improved quality of current reassembly as compared to previous one. We found major misassemblies in previously assembled chromosome 12 (A_Ca9) of G. arboreum particularly in anchoring and orienting of scaffolds into a pseudo-chromosome. Further, homologous chromosomes 12 of G. raimondii (D_D08) and G. arboreum (A_A12) contained almost equal number of transcription factor (TF) related genes, and showed good collinear relationship with each other. As well, a higher rate of gene loss was found in corresponding homologous chromosomes of tetraploid (AD_A12 and AD_D12) than diploid (A_A12 and D_D08) cotton, signifying that gene loss is likely a continuing process in chromosomal evolution of tetraploid cotton. CONCLUSION: This study offers a more accurate strategy to correct misassemblies in sequenced draft genomes of cotton which will provide further insights towards its genome organization.

Construction of Gossypium barbadense Mutant Library Provides Genetic Resources for Cotton Germplasm Improvement.

Allotetraploid cotton (Gossypium hirsutum and Gossypium barbadense) are cultivated worldwide for its white fiber. For centuries, conventional breeding approaches increase cotton yield at the cost of extensive erosion of natural genetic variability. Sea Island cotton (G. barbadense) is known for its superior fiber quality, but show poor adaptability as compared to Upland cotton. Here, in this study, we use ethylmethanesulfonate (EMS) as a mutagenic agent to induce genome-wide point mutations to improve the current germplasm resources of Sea Island cotton and develop diverse breeding lines with improved adaptability and excellent economic traits. We determined the optimal EMS experimental procedure suitable for construction of cotton mutant library. At M6 generation, mutant library comprised of lines with distinguished phenotypes of the plant architecture, leaf, flower, boll, and fiber. Genome-wide analysis of SNP distribution and density in yellow leaf mutant reflected the better quality of mutant library. Reduced photosynthetic efficiency and transmission electron microscopy of yellow leaf mutants revealed the effect of induced mutations at physiological and cellular level. Our mutant collection will serve as the valuable resource for basic research on cotton functional genomics, as well as cotton breeding.

Testing multiplicative terms in AMMI and GGE models for multienvironment trials with replicates.

KEY MESSAGE: For analysing multienvironment trials with replicates, a resampling-based method is proposed for testing significance of multiplicative interaction terms in AMMI and GGE models, which is superior compared to contending methods in robustness to heterogeneity of variance. The additive main effects and multiplicative interaction model and genotype main effects and genotype-by-environment interaction model are commonly used for the analysis of multienvironment trial data. Agronomists and plant breeders are frequently using these models for cultivar trials repeated across different environments and/or years. In these models, it is crucial to decide how many significant multiplicative interaction terms to retain. Several tests have been proposed for this purpose when replicate data are available; however, all of them assume that errors are normally distributed with a homogeneous variance. Here, we propose resampling-based methods for multienvironment trial data with replicates, which are free from these distributional assumptions. The methods are compared with competing parametric tests. In an extensive simulation study based on two multienvironment trials, it was found that the proposed methods performed well in terms of Type-I error rates regardless of the distribution of errors. The proposed method even outperforms the robust [Formula: see text] test when the assumptions of normality and homogeneity of variance are violated.

Recent insights into cotton functional genomics: progress and future perspectives.

Functional genomics has transformed from futuristic concept to well-established scientific discipline during the last decade. Cotton functional genomics promise to enhance the understanding of fundamental plant biology to systematically exploit genetic resources for the improvement of cotton fibre quality and yield, as well as utilization of genetic information for germplasm improvement. However, determining the cotton gene functions is a much more challenging task, which has not progressed at a rapid pace. This article presents a comprehensive overview of the recent tools and resources available with the major advances in cotton functional genomics to develop elite cotton genotypes. This effort ultimately helps to filter a subset of genes that can be used to assemble a final list of candidate genes that could be employed in future novel cotton breeding programme. We argue that next stage of cotton functional genomics requires the draft genomes refinement, re-sequencing broad diversity panels with the development of high-throughput functional genomics tools and integrating multidisciplinary approaches in upcoming cotton improvement programmes.

Stability of Single-Parent Gene Expression Complementation in Maize Hybrids upon Water Deficit Stress.

Heterosis is the superior performance of F1 hybrids compared with their homozygous, genetically distinct parents. In this study, we monitored the transcriptomic divergence of the maize (Zea mays) inbred lines B73 and Mo17 and their reciprocal F1 hybrid progeny in primary roots under control and water deficit conditions simulated by polyethylene glycol treatment. Single-parent expression (SPE) of genes is an extreme instance of gene expression complementation, in which genes are active in only one of two parents but are expressed in both reciprocal hybrids. In this study, 1,997 genes only expressed in B73 and 2,024 genes only expressed in Mo17 displayed SPE complementation under control and water deficit conditions. As a consequence, the number of active genes in hybrids exceeded the number of active genes in the parental inbred lines significantly independent of treatment. SPE patterns were substantially more stable to expression changes by water deficit treatment than other genotype-specific expression profiles. While, on average, 75% of all SPE patterns were not altered in response to polyethylene glycol treatment, only 17% of the remaining genotype-specific expression patterns were not changed by water deficit. Nonsyntenic genes that lack syntenic orthologs in other grass species, and thus evolved late in the grass lineage, were significantly overrepresented among SPE genes. Hence, the significant overrepresentation of nonsyntenic genes among SPE patterns and their stability under water limitation might suggest a function of these genes during the early developmental manifestation of heterosis under fluctuating environmental conditions in hybrid progeny of the inbred lines B73 and Mo17.

Co-expression of GR79 EPSPS and GAT yields herbicide-resistant cotton with low glyphosate residues.

Glyphosate-resistant (GR) crops have been adopted on a massive scale by North and South American farmers. Currently, about 80% of the 120 million hectares of the global genetically modified (GM) crops are GR crop varieties. However, the adoption of GR plants in China has not occurred at the same pace, owing to several factors including, among other things, labour markets and the residual effects of glyphosate in transgenic plants. Here, we report the co-expression of codon-optimized forms of GR79 EPSPS and N-acetyltransferase (GAT) genes in cotton. We found five times more resistance to glyphosate with 10-fold reduction in glyphosate residues in two pGR79 EPSPS-pGAT co-expression cotton lines, GGCO2 and GGCO5. The GGCO2 line was used in a hybridization programme to develop new GR cottons. Field trials at five locations during three growing seasons showed that pGR79-pGAT transgenic cotton lines have the same agronomic performance as conventional varieties, but were USD 390-495 cheaper to produce per hectare because of the high cost of conventional weed management practices. Our strategy to pyramid these genes clearly worked and thus offers attractive promise for the engineering and breeding of highly resistant low-glyphosate-residue cotton varieties.

A high-resolution tissue-specific proteome and phosphoproteome atlas of maize primary roots reveals functional gradients along the root axes.

A high-resolution proteome and phosphoproteome atlas of four maize (Zea mays) primary root tissues, the cortex, stele, meristematic zone, and elongation zone, was generated. High-performance liquid chromatography coupled with tandem mass spectrometry identified 11,552 distinct nonmodified and 2,852 phosphorylated proteins across the four root tissues. Two gradients reflecting the abundance of functional protein classes along the longitudinal root axis were observed. While the classes RNA, DNA, and protein peaked in the meristematic zone, cell wall, lipid metabolism, stress, transport, and secondary metabolism culminated in the differentiation zone. Functional specialization of tissues is underscored by six of 10 cortex-specific proteins involved in flavonoid biosynthesis. Comparison of this data set with high-resolution seed and leaf proteome studies revealed 13% (1,504/11,552) root-specific proteins. While only 23% of the 1,504 root-specific proteins accumulated in all four root tissues, 61% of all 11,552 identified proteins accumulated in all four root tissues. This suggests a much higher degree of tissue-specific functionalization of root-specific proteins. In summary, these data illustrate the remarkable plasticity of the proteomic landscape of maize primary roots and thus provide a starting point for gaining a better understanding of their tissue-specific functions.

Extensive tissue-specific transcriptomic plasticity in maize primary roots upon water deficit.

Water deficit is the most important environmental constraint severely limiting global crop growth and productivity. This study investigated early transcriptome changes in maize (Zea mays L.) primary root tissues in response to moderate water deficit conditions by RNA-Sequencing. Differential gene expression analyses revealed a high degree of plasticity of the water deficit response. The activity status of genes (active/inactive) was determined by a Bayesian hierarchical model. In total, 70% of expressed genes were constitutively active in all tissues. In contrast, <3% (50 genes) of water deficit-responsive genes (1915) were consistently regulated in all tissues, while >75% (1501 genes) were specifically regulated in a single root tissue. Water deficit-responsive genes were most numerous in the cortex of the mature root zone and in the elongation zone. The most prominent functional categories among differentially expressed genes in all tissues were 'transcriptional regulation' and 'hormone metabolism', indicating global reprogramming of cellular metabolism as an adaptation to water deficit. Additionally, the most significant transcriptomic changes in the root tip were associated with cell wall reorganization, leading to continued root growth despite water deficit conditions. This study provides insight into tissue-specific water deficit responses and will be a resource for future genetic analyses and breeding strategies to develop more drought-tolerant maize cultivars.

Transcriptomic complexity in young maize primary roots in response to low water potentials.

BACKGROUND: Widespread and more frequently occurring drought conditions are a consequence of global warming and increase the demand for tolerant crop varieties to feed the growing world population. A better understanding of the molecular mechanisms underlying the water deficit response of crops will enable targeted breeding strategies to develop robust cultivars. RESULTS: In the present study, the transcriptional response of maize (Zea mays L.) primary roots to low water potentials was monitored by RNA sequencing (RNA-Seq) experiments. After 6 h and 24 h of mild (-0.2 MPa) and severe (-0.8 MPa) water deficit conditions, the primary root transcriptomes of seedlings grown under water deficit and control conditions were compared. The number of responsive genes was dependent on and increased with intensification of water deficit treatment. After short-term mild and severe water deficit 249 and 3,000 genes were differentially expressed, respectively. After a 24 h treatment the number of affected genes increased to 7,267 and 12,838 for mild and severe water deficit, respectively, including more than 80% of the short-term responsive genes. About half of the differentially expressed genes were up-regulated and maximal fold-changes increased with treatment intensity to more than 300-fold. A consensus set of 53 genes was differentially regulated independently of the nature of deficit treatment. Characterization revealed an overrepresentation of the Gene Ontology (GO) categories "oxidoreductase activity" and "heme binding" among regulated genes connecting the water deficit response to ROS metabolism. CONCLUSION: This study gives a comprehensive insight in water deficit responsive genes in young maize primary roots and provides a set of candidate genes that merit further genetic analyses in the future.

Comparative transcriptome profiling of maize coleoptilar nodes during shoot-borne root initiation.

Maize (Zea mays) develops an extensive shoot-borne root system to secure water and nutrient uptake and to provide anchorage in the soil. In this study, early coleoptilar node (first shoot node) development was subjected to a detailed morphological and histological analysis. Subsequently, microarray profiling via hybridization of oligonucleotide microarrays representing transcripts of 31,355 unique maize genes at three early stages of coleoptilar node development was performed. These pairwise comparisons of wild-type versus mutant rootless concerning crown and seminal roots (rtcs) coleoptilar nodes that do not initiate shoot-borne roots revealed 828 unique transcripts that displayed RTCS-dependent expression. A stage-specific functional analysis revealed overrepresentation of "cell wall," "stress," and "development"-related transcripts among the differentially expressed genes. Differential expression of a subset of 15 of 828 genes identified by these microarray experiments was independently confirmed by quantitative real-time-polymerase chain reaction. In silico promoter analyses revealed that 100 differentially expressed genes contained at least one LATERAL ORGAN BOUNDARIES domain (LBD) motif within 1 kb upstream of the ATG start codon. Electrophoretic mobility shift assay experiments demonstrated RTCS binding for four of these promoter sequences, supporting the notion that differentially accumulated genes containing LBD motifs are likely direct downstream targets of RTCS.

Molecular markers and cotton genetic improvement: current status and future prospects.

Narrow genetic base and complex allotetraploid genome of cotton (Gossypium hirsutum L.) is stimulating efforts to avail required polymorphism for marker based breeding. The availability of draft genome sequence of G. raimondii and G. arboreum and next generation sequencing (NGS) technologies facilitated the development of high-throughput marker technologies in cotton. The concepts of genetic diversity, QTL mapping, and marker assisted selection (MAS) are evolving into more efficient concepts of linkage disequilibrium, association mapping, and genomic selection, respectively. The objective of the current review is to analyze the pace of evolution in the molecular marker technologies in cotton during the last ten years into the following four areas: (i) comparative analysis of low- and high-throughput marker technologies available in cotton, (ii) genetic diversity in the available wild and improved gene pools of cotton, (iii) identification of the genomic regions within cotton genome underlying economic traits, and (iv) marker based selection methodologies. Moreover, the applications of marker technologies to enhance the breeding efficiency in cotton are also summarized. Aforementioned genomic technologies and the integration of several other omics resources are expected to enhance the cotton productivity and meet the global fiber quantity and quality demands.

A REML method for the evidence-splitting model in network meta-analysis.

Checking for possible inconsistency between direct and indirect evidence is an important task in network meta-analysis. Recently, an evidence-splitting (ES) model has been proposed, that allows separating direct and indirect evidence in a network and hence assessing inconsistency. A salient feature of this model is that the variance for heterogeneity appears in both the mean and the variance structure. Thus, full maximum likelihood (ML) has been proposed for estimating the parameters of this model. Maximum likelihood is known to yield biased variance component estimates in linear mixed models, and this problem is expected to also affect the ES model. The purpose of the present paper, therefore, is to propose a method based on residual (or restricted) maximum likelihood (REML). Our simulation shows that this new method is quite competitive to methods based on full ML in terms of bias and mean squared error. In addition, some limitations of the ES model are discussed. While this model splits direct and indirect evidence, it is not a plausible model for the cause of inconsistency.

Co-hydrothermal carbonization with process water recirculation as a valuable strategy to enhance hydrochar recovery with high energy efficiency.

This study aims at valorizing the residual aqueous phase from hydrothermal carbonization (HTC) of Sicilian agro-wastes in order to enhance the hydrochar recovery, positively affecting the process energy balance. Process waters (PW) obtained from HTC and co-HTC using orange peel waste and fennel plant residues were used as recycled solvent in experiments carried out at the temperatures of 180 and 230 °C. The results showed that an additional hydrochar formation was promoted during recirculation of solvent, leading to average increments of solid mass yield of 10.5 wt% for tests conducted at 180 °C and 3.9 wt% for 230 °C. After five consecutive recirculation phases in co-HTC runs, the hydrochar yield increased up to 18.2 wt%. The low H/C and O/C atomic ratios values, found after recirculation, indicate that organic acids, accumulated in the PW, may catalyze the process and promote the biomass deoxygenation by boosting dehydration and decarboxylation. The recovered PWs from conversion steps with deionized water were also carbonized in absence of the solid feedstock in order to quantify their contribution in hydrochar formation during recirculation and thus the synergistic interactions. After recirculation, energy recovery averagely augmented by more than threefold, showing that the proposed strategy could significantly improve the sustainability of HTC.