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Meta-QTL and ortho-MQTL analyses identified genomic regions controlling rice yield, yield-related traits and root architecture under water deficit conditions.
Khahani, B, Tavakol, E, Shariati, V, Rossini, L
Scientific reports. 2021;(1):6942
Abstract
Meta-QTL (MQTL) analysis is a robust approach for genetic dissection of complex quantitative traits. Rice varieties adapted to non-flooded cultivation are highly desirable in breeding programs due to the water deficit global problem. In order to identify stable QTLs for major agronomic traits under water deficit conditions, we performed a comprehensive MQTL analysis on 563 QTLs from 67 rice populations published from 2001 to 2019. Yield and yield-related traits including grain weight, heading date, plant height, tiller number as well as root architecture-related traits including root dry weight, root length, root number, root thickness, the ratio of deep rooting and plant water content under water deficit condition were investigated. A total of 61 stable MQTLs over different genetic backgrounds and environments were identified. The average confidence interval of MQTLs was considerably refined compared to the initial QTLs, resulted in the identification of some well-known functionally characterized genes and several putative novel CGs for investigated traits. Ortho-MQTL mining based on genomic collinearity between rice and maize allowed identification of five ortho-MQTLs between these two cereals. The results can help breeders to improve yield under water deficit conditions.
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2.
Root and shoot competition lead to contrasting competitive outcomes under water stress: A systematic review and meta-analysis.
Foxx, AJ, Fort, F
PloS one. 2019;(12):e0220674
Abstract
BACKGROUND Competition is a critical process that shapes plant communities and interacts with environmental constraints. There are surprising knowledge gaps related to mechanisms that belie competitive processes, though important to natural communities and agricultural systems: the contribution of different plant parts on competitive outcomes and the effect of environmental constraints on these outcomes. OBJECTIVE Studies that partition competition into root-only and shoot-only interactions assess whether plant parts impose different competitive intensities using physical partitions and serve as an important way to fill knowledge gaps. Given predicted drought escalation due to climate change, we focused a systematic review-including a meta-analysis on the effects of water supply and competitive outcomes. METHODS We searched ISI Web of Science for peer-reviewed studies and found 2042 results. From which eleven suitable studies, five of which had extractable information of 80 effect sizes on 10 species to test these effects. We used a meta-analysis to compare the log response ratios (lnRR) on biomass for responses to competition between roots, shoots, and full plants at two water levels. RESULTS Water availability treatment and competition treatment (root-only, shoot-only, and full plant competition) significantly interacted to affect plant growth responses (p < 0.0001). Root-only and full plant competition are more intense in low water availability (-1.2 and -0.9 mean lnRR, respectively) conditions than shoot-only competition (-0.2 mean lnRR). However, shoot-only competition in high water availability was the most intense (- 0.78 mean lnRR) compared to root-only and full competition (-0.5 and 0.61 mean lnRR, respectively) showing the opposite pattern to low water availability. These results also show that the intensity of full competition is similar to root-only competition and that low water availability intensifies root competition while weakening shoot competition. CONCLUSIONS The outcome that competition is most intense between roots at low water availability emphasizes the importance of root competition and these patterns of competition may shift in a changing climate, creating further urgency for further studies to fil knowledge gaps addressing issues of drought on plant interactions and communities.
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3.
Effects of inorganic nitrate and beetroot supplementation on endothelial function: a systematic review and meta-analysis.
Lara, J, Ashor, AW, Oggioni, C, Ahluwalia, A, Mathers, JC, Siervo, M
European journal of nutrition. 2016;(2):451-459
Abstract
BACKGROUND Diets rich in inorganic nitrate are associated with lower blood pressure, an effect that may be mediated by an improvement of endothelial function (EF). Therefore, a systematic review and meta-analysis of randomised controlled trials (RCTs) were conducted to examine the effects of inorganic nitrate and beetroot supplementation on measures of EF. METHODS MEDLINE, EMBASE and Scopus databases were searched from inception until November 2014. Specific inclusion criteria were as follows: (1) RCTs; (2) trials comparing inorganic nitrate or beetroot supplementation with placebo control groups; and (3) trials reporting effects of these interventions on outcomes of vascular function. Random-effect models were used to assess the pooled effect sizes showed as standardised mean differences (SMD). RESULTS Nine crossover trials and three parallel trials met our inclusion criteria. The trials were conducted between 2008 and 2014 and included a total of 246 participants with 10-64 participants per study. The duration of each intervention ranged from 1.5 h to 28 days. Inorganic nitrate and beetroot consumption was associated with an improvement in vascular function (SMD 0.36; 95 % CI 0.16, 0.56; P < 0.001). The effect on EF was significantly associated with the dose of inorganic nitrate (β = 0.04, SE = 0.01, P < 0.001), age (β = -0.01, SE = 0.004, P = 0.02), baseline BMI (β = -0.04, SE = 0.02, P = 0.05) and systolic BP (β = -0.01, SE = 0.005, P = 0.02). CONCLUSIONS Inorganic nitrate and beetroot supplementation was associated with beneficial effects on EF. These effects appear to be reduced in older subjects and in subjects with greater cardiometabolic risk.
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4.
Arbuscular mycorrhizal symbiosis alters stomatal conductance of host plants more under drought than under amply watered conditions: a meta-analysis.
Augé, RM, Toler, HD, Saxton, AM
Mycorrhiza. 2015;(1):13-24
Abstract
Stomata regulate rates of carbon assimilation and water loss. Arbuscular mycorrhizal (AM) symbioses often modify stomatal behavior and therefore play pivotal roles in plant productivity. The size of the AM effect on stomatal conductance to water vapor (g s ) has varied widely, has not always been apparent, and is unpredictable. We conducted a meta-analysis of 460 studies to determine the size of the AM effect under ample watering and drought and to examine how experimental conditions have influenced the AM effect. Across all host and symbiont combinations under all soil moisture conditions, AM plants have shown 24 % higher g s than nonmycorrhizal (NM) controls. The promotion of g s has been over twice as great during moderate drought than under amply watered conditions. The AM influence on g s has been even more pronounced under severe drought, with over four times the promotion observed with ample water. Members of the Claroideoglomeraceae, Glomeraceae, and other AM families stimulated g s by about the same average amount. Colonization by native AM fungi has produced the largest promotion. Among single-AM symbionts, Glomus deserticola, Claroideoglomus etunicatum, and Funneliformis mosseae have had the largest average effects on g s across studies. Dicotyledonous hosts, especially legumes, have been slightly more responsive to AM symbiosis than monocotyledonous hosts, and C3 plants have shown over twice the AM-induced promotion of C4 plants. The extent of root colonization is important, with heavily colonized plants showing ×10 the g s promotion of lightly colonized plants. AM promotion of g s has been larger in growth chambers and in the field than in greenhouse studies, almost ×3 as large when plants were grown under high light than low light, and ×2.5 as large in purely mineral soils than in soils having an organic component. When AM plants have been compared with NM controls given NM pot culture, they have shown only half the promotion of g s as NM plants not given anything at inoculation to control for associated soil organisms. The AM effect has been much greater when AM plants were larger or had more phosphorus than NM controls. These findings should assist in further investigations of predictions and mechanisms of the AM influence on host g s .
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5.
Reduction of transpiration and altered nutrient allocation contribute to nutrient decline of crops grown in elevated CO(2) concentrations.
McGrath, JM, Lobell, DB
Plant, cell & environment. 2013;(3):697-705
Abstract
Plants grown in elevated [CO(2) ] have lower protein and mineral concentrations compared with plants grown in ambient [CO(2) ]. Dilution by enhanced production of carbohydrates is a likely cause, but it cannot explain all of the reductions. Two proposed, but untested, hypotheses are that (1) reduced canopy transpiration reduces mass flow of nutrients to the roots thus reducing nutrient uptake and (2) changes in metabolite or enzyme concentrations caused by physiological changes alter requirements for minerals as protein cofactors or in other organic complexes, shifting allocation between tissues and possibly altering uptake. Here, we use the meta-analysis of previous studies in crops to test these hypotheses. Nutrients acquired mostly by mass flow were decreased significantly more by elevated [CO(2) ] than nutrients acquired by diffusion to the roots through the soil, supporting the first hypothesis. Similarly, Mg showed large concentration declines in leaves and wheat stems, but smaller decreases in other tissues. Because chlorophyll requires a large fraction of total plant Mg, and chlorophyll concentration is reduced by growth in elevated [CO(2) ], this supports the second hypothesis. Understanding these mechanisms may guide efforts to improve nutrient content, and allow modeling of nutrient changes and health impacts under future climate change scenarios.