Identifying genetic diversity for improved nitrogen-use efficiency and associated physiological traits in wheat (Triticum aestivum L.) and wheat amphidiploids

Wheat is one of the most widely consumed staple crops in the world including India and its demand is increasing with increasing population. Increased grain yield (GY) has been associated with increased use of nitrogen (N) fertilizers which represent a significant environmental and production cost. Developing cultivars which have higher grain yield but use N efficiently may allow reduced fertilizer N inputs. The objectives of this study were to: (i) quantify the genetic variability in N use-efficiency (grain dry matter (DM) yield per unit N available from soil and fertilizer, NUE) in a panel of modern Indian wheat cultivars and find new genetic variation in a panel of amphidiploids produced by crossing hexaploid bread wheat with wild wheat relatives and (ii) identify traits and understand physiological mechanisms determining improved NUE to exploit for development of new N efficient cultivars. Thirty Indian elite bread wheat cultivars and 18 amphidiploid lines along with their five respective bread wheat parents were tested under high N (HN) and low N (LN) conditions in two years in field experiments at Agharkar Research Institute, Pune, India (2013 and 2014) and in glasshouse experiments at Nottingham University, UK, (2015 and 2016), respectively. Detailed growth analysis was conducted including GY, above-ground dry matter (AGDM), DM and N partitioning at anthesis and at harvest along with N remobilization efficiency (NRE) in the field experiment. Senescence kinetics of the flag-leaf were assessed from a visual score weekly from anthesis to complete canopy senescence in both sets of experiments. Physiological traits were assessed including flag-leaf light-saturated photosynthetic rate (Amax) under HN conditions in the field experiment and under both HN and LN conditions in glasshouse experiment. Flag-leaf relative chlorophyll content (SPAD) under HN and LN conditions was measured in both experiments; and Normalized Difference Vegetative Index (NDVI) under HN and LN conditions in field experiment. 2D seedling root phenotyping was carried out on subset of 12 genotypes selected based on contrasting performance under LN conditions from both the field and glasshouse experiments. In field experiments, GY was reduced under low N (LN) conditions on average by 1.46 t ha−1 (28%). Crop above-ground N-uptake at harvest on average was reduced from 16.2 kg N ha−1 under HN to 8.5 kg N ha−1 under LN conditions while N-utilization efficiency (grain DM yield per unit above-ground N uptake at harvest; NUtE) increased from 32.7 to 44.6 g DM g−1 N. Significant N × genotype level interaction was observed for GY, N uptake at harvest and NUtE. Overall genetic variability in GY and NUE (which ranged from 15.6 - 23.7 g DM g−1 N under LN; P<0.001) related mainly to differences in N uptake rather than NUtE. Overall, cultivars ranged significantly at anthesis in N accumulation in the flag-leaf N (1.1 -2.2 g N m−2 at HN and 0.5-1.0 g N m−2 at LN), the stem and remaining leaf with sheath (5.78-11.97 at HN and 3.61- 6.33 g N m−2 at LN) (P=0.01), and the ear (2.91-6.13 at HN and 2.06-4.23 g N m−2 at LN) (P<0.001). Cultivars ranged in N partitioning index (proportion of above-ground N in the crop component, NPI) at anthesis for the flag-leaf from 0.08 to 0.16 at HN and 0.07 to 0.13 at LN (P< 0.001); and for the stem-and remaining leaf with sheath from 0.54 to 0.68 at HN and from 0.52 to 0.65 at LN (P<0.001) and for ear from 0.21 to 0.34 at HN and from 0.28 to 0.41 at LN (P<0.001). The post-anthesis NRE was positively associated with the duration of flag-leaf senescence amongst cultivars under LN. Genetic variation in grain yield and grain N% (through N dilution effects) appeared to be mainly influenced by pre-anthesis N accumulation rather than post-anthesis N remobilization under LN conditions. Under N stress conditions, there was evidence that NRE was a determinant of genetic variation in grain N%. Flag-leaf Amax was positively associated with AGDM (P=0.02), GY (P=0.14), and specific leaf N at anthesis (P=0.046). Flag-leaf onset (VS.OnsetRP) and end (VS.EndRP) of senescence was positively associated with GY, AGDM and NRE in both N treatments. In the glasshouse experiments, out of 18 amphidiploid lines, two lines under HN and three lines under LN conditions showed transgressive segregation (TS) above the bread wheat parent for pre-anthesis Amax and 12 lines under HN and 7 lines under LN conditions showed TS for post-anthesis Amax. In addition, higher expression than the bread wheat parent was observed for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94 under HN conditions for GY and for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94 under HN conditions for AGDM showing potential to exploit these genotypes for wide crossing for NUE wheat breeding. Seedling root architectural traits including seminal root number per plant showed association with field and glasshouse GY and NUE related traits in HN and LN conditions. Overall amphidiploids showed evidence for increased root depth than bread wheat cultivars in the hydroponics seedling platform under both HN and LN conditions. In summary: • N-use efficiency in thirty Indian wheat cultivars in the field was correlated with onset of flag-leaf senescence under high N and low N conditions and senescence timing was correlated with N accumulation at anthesis. • Yield response to N limitation of 30 wheat cultivars was associated with responses in N uptake at anthesis under both N conditions. • The grain yield in N stressed crops for the 30 cultivars was limited by post-anthesis source capacity. • Three amphidiploids lines (Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94) in glasshouse conditions showed higher flag-leaf photosynthesis rate and prolonged flag leaf green area than their recurrent parents. • The 2D seedling RSAT study showed seminal root number was correlated amongst 12 Indian wheat cultivars and amphidiploids with grain yield per shoot under high and low N conditions

Genotype and environment interaction study shows fungal diseases and heat stress are detrimental to spring wheat production in Sweden

Spring wheat is an economically important crop for Scandinavia and its cultivation is likely to be affected by climate change. The current study focused on wheat yield in recent years, during which climate change-related yield fluctuations have been more pronounced than previously observed. Here, effects of the environment, together with the genotype and fungicide treatment was evaluated. Spring wheat multi-location trials conducted at five locations between 2016 and 2020 were used to understand effects of the climate and fungicides on wheat yield. The results showed that the environment has a strong effect on grain yield, followed by the genotype effect. Moreover, temperature has a stronger (negative) impact than rainfall on grain yield and crop growing duration. Despite a low rainfall in the South compared to the North, the southern production region (PR) 2 had the highest yield performance, indicating the optimal environment for spring wheat production. The fungicide treatment effect was significant in 2016, 2017 and 2020. Overall, yield reduction due to fungal diseases ranged from 0.98 (2018) to 13.3% (2017) and this reduction was higher with a higher yield. Overall yield reduction due to fungal diseases was greater in the South (8.9%) than the North zone (5.3%). The genotypes with higher tolerance to diseases included G4 (KWS Alderon), G14 (WPB 09SW025-11), and G23 (SW 11360) in 2016; G24 (SW 11360), G25 (Millie), and G19 (SEC 526-07-2) in 2017; and G19 (WPB 13SW976-01), G12 (Levels), and G18 (SW 141011) in 2020. The combined best performing genotypes for disease tolerance and stable and higher yield in different locations were KWS Alderon, SEC 526-07-2, and WPB 13SW976-01 with fungicide treatment and WPB Avonmore, SEC 526-07-2, SW 131323 without fungicide treatment. We conclude that the best performing genotypes could be recommended for Scandinavian climatic conditions with or without fungicide application and that developing heat-tolerant varieties for Scandinavian countries should be prioritized

Functional phenomics for improved climate resilience in Nordic agriculture

The five Nordic countries span the most northern region for field cultivation in the world. This presents challenges per se with short growing seasons, long days and a need for frost tolerance. Climate change has additionally increased risks for micro-droughts and water logging as well as pathogens and pests expanding northwards. Thus, Nordic agriculture demands crops that are adapted to the special Nordic growth conditions and future climate scenarios. A focus on crop varieties and traits important to Nordic agriculture, including the unique resource of nutritious wild crops, can meet these needs. In fact, with a future longer growing season due to climate change the region could contribute proportionally more to the global agricultural production. This also applies to other northern regions, including the Arctic. To address current growth conditions, mitigate impacts of climate change and meet market demands, the adaptive capacity of crops that both perform well in northern latitudes and are more climate resilient has to be increased, and better crop management systems be built. This requires functional phenomics approaches that integrate versatile high-throughput phenotyping, physiology and bioinformatics. This review stresses key target traits, the opportunities of latitudinal studies and infrastructure needs for phenotyping to support Nordic agriculture.Peer reviewe

Functional phenomics for improved climate resilience in Nordic agriculture

The five Nordic countries span the most northern region for field cultivation in the world. This presents challenges per se with short growing seasons, long days and a need for frost tolerance. Climate change has additionally increased risks for micro-droughts and water logging as well as pathogens and pests expanding northwards. Thus, Nordic agriculture demands crops that are adapted to the special Nordic growth conditions and future climate scenarios. A focus on crop varieties and traits important to Nordic agriculture, including the unique resource of nutritious wild crops, can meet these needs. In fact, with a future longer growing season due to climate change the region could contribute proportionally more to the global agricultural production. This also applies to other northern regions, including the Arctic. To address current growth conditions, mitigate impacts of climate change and meet market demands, the adaptive capacity of crops that both perform well in northern latitudes and are more climate resilient has to be increased, and better crop management systems be built. This requires functional phenomics approaches that integrate versatile high-throughput phenotyping, physiology and bioinformatics. This review stresses key target traits, the opportunities of latitudinal studies and infrastructure needs for phenotyping to support Nordic agriculture.Peer reviewe

Identifying variation for N-use efficiency and associated traits in amphidiploids derived from hybrids of bread wheat and the genera Aegilops, Secale, Thinopyrum and Triticum

Future genetic progress in wheat grain yield will depend on increasing biomass and this must be achieved without commensurate increases in nitrogen (N) fertilizer inputs to minimize environmental impacts. In recent decades there has been a loss of genetic diversity in wheat through plant breeding. However, new genetic diversity can be created by incorporating genes into bread wheat from wild wheat relatives. Our objectives were to investigate amphidiploids derived from hybrids of bread wheat (Triticum aestivum L.) and related species from the genera Aegilops, Secale, Thinopyrum and Triticum for expression of higher biomass, N-use efficiency (NUE) and leaf photosynthesis rate compared to their bread wheat parents under high and low N conditions. Eighteen amphidiploid lines and their bread wheat parents were examined in high N (HN) and low N (LN) treatments under glasshouse conditions in two years. Averaged across years, grain yield reduced by 38% under LN compared to HN conditions (P = 0.004). Three amphidiploid lines showed positive transgressive segregation compared to their bread wheat parent for biomass per plant under HN conditions. Positive transgressive segregation was also identified for flag-leaf photosynthesis both pre-anthesis and post-anthesis under HN and LN conditions. For N uptake per plant at maturity positive transgressive segregation was identified for one amphidiploid line under LN conditions. Our results indicated that introgressing traits from wild relatives into modern bread wheat germplasm offers scope to raise biomass and N-use effciency in both optimal and low N availability environments

Yield and Quality in Purple-Grained Wheat Isogenic Lines

Breeding programs for purple wheat are underway in many countries but there is a lack of information on the effects of Pp (purple pericarp) genes on agronomic and quality traits in variable environments and along the product chain (grain-flour-bread). This study was based on unique material: two pairs of isogenic lines in a spring wheat cv. Saratovskaya-29 (S29) background differing only in Pp genes and grain color. In 2017, seven experiments were conducted in Kazakhstan, Russia, and Turkey with a focus on genotype and environment interaction and, in 2018, one experiment in Turkey with a focus on grain, flour, and bread quality. The eect of environment was greater compared to genotype for the productivity and quality traits studied. Nevertheless, several important traits, such as grain color and anthocyanin content, are closely controlled by genotype, offering the opportunity for selection. Phenolic content in purple-grained lines was not significantly higher in whole wheat flour than in red-colored lines. However, this trait was significantly higher in bread. For antioxidant activities, no differences between the genotypes were detected in both experiments. Comparison of two sources of Pp genes demonstrated that the lines originating from cv. Purple Feed had substantially improved productivity and quality traits compared to those from cv. Purple

Identifying genetic diversity for improved nitrogen-use efficiency and associated physiological traits in wheat (Triticum aestivum L.) and wheat amphidiploids

Wheat is one of the most widely consumed staple crops in the world including India and its demand is increasing with increasing population. Increased grain yield (GY) has been associated with increased use of nitrogen (N) fertilizers which represent a significant environmental and production cost. Developing cultivars which have higher grain yield but use N efficiently may allow reduced fertilizer N inputs. The objectives of this study were to: (i) quantify the genetic variability in N use-efficiency (grain dry matter (DM) yield per unit N available from soil and fertilizer, NUE) in a panel of modern Indian wheat cultivars and find new genetic variation in a panel of amphidiploids produced by crossing hexaploid bread wheat with wild wheat relatives and (ii) identify traits and understand physiological mechanisms determining improved NUE to exploit for development of new N efficient cultivars. Thirty Indian elite bread wheat cultivars and 18 amphidiploid lines along with their five respective bread wheat parents were tested under high N (HN) and low N (LN) conditions in two years in field experiments at Agharkar Research Institute, Pune, India (2013 and 2014) and in glasshouse experiments at Nottingham University, UK, (2015 and 2016), respectively. Detailed growth analysis was conducted including GY, above-ground dry matter (AGDM), DM and N partitioning at anthesis and at harvest along with N remobilization efficiency (NRE) in the field experiment. Senescence kinetics of the flag-leaf were assessed from a visual score weekly from anthesis to complete canopy senescence in both sets of experiments. Physiological traits were assessed including flag-leaf light-saturated photosynthetic rate (Amax) under HN conditions in the field experiment and under both HN and LN conditions in glasshouse experiment. Flag-leaf relative chlorophyll content (SPAD) under HN and LN conditions was measured in both experiments; and Normalized Difference Vegetative Index (NDVI) under HN and LN conditions in field experiment. 2D seedling root phenotyping was carried out on subset of 12 genotypes selected based on contrasting performance under LN conditions from both the field and glasshouse experiments. In field experiments, GY was reduced under low N (LN) conditions on average by 1.46 t ha−1 (28%). Crop above-ground N-uptake at harvest on average was reduced from 16.2 kg N ha−1 under HN to 8.5 kg N ha−1 under LN conditions while N-utilization efficiency (grain DM yield per unit above-ground N uptake at harvest; NUtE) increased from 32.7 to 44.6 g DM g−1 N. Significant N × genotype level interaction was observed for GY, N uptake at harvest and NUtE. Overall genetic variability in GY and NUE (which ranged from 15.6 - 23.7 g DM g−1 N under LN; P<0.001) related mainly to differences in N uptake rather than NUtE. Overall, cultivars ranged significantly at anthesis in N accumulation in the flag-leaf N (1.1 -2.2 g N m−2 at HN and 0.5-1.0 g N m−2 at LN), the stem and remaining leaf with sheath (5.78-11.97 at HN and 3.61- 6.33 g N m−2 at LN) (P=0.01), and the ear (2.91-6.13 at HN and 2.06-4.23 g N m−2 at LN) (P<0.001). Cultivars ranged in N partitioning index (proportion of above-ground N in the crop component, NPI) at anthesis for the flag-leaf from 0.08 to 0.16 at HN and 0.07 to 0.13 at LN (P< 0.001); and for the stem-and remaining leaf with sheath from 0.54 to 0.68 at HN and from 0.52 to 0.65 at LN (P<0.001) and for ear from 0.21 to 0.34 at HN and from 0.28 to 0.41 at LN (P<0.001). The post-anthesis NRE was positively associated with the duration of flag-leaf senescence amongst cultivars under LN. Genetic variation in grain yield and grain N% (through N dilution effects) appeared to be mainly influenced by pre-anthesis N accumulation rather than post-anthesis N remobilization under LN conditions. Under N stress conditions, there was evidence that NRE was a determinant of genetic variation in grain N%. Flag-leaf Amax was positively associated with AGDM (P=0.02), GY (P=0.14), and specific leaf N at anthesis (P=0.046). Flag-leaf onset (VS.OnsetRP) and end (VS.EndRP) of senescence was positively associated with GY, AGDM and NRE in both N treatments. In the glasshouse experiments, out of 18 amphidiploid lines, two lines under HN and three lines under LN conditions showed transgressive segregation (TS) above the bread wheat parent for pre-anthesis Amax and 12 lines under HN and 7 lines under LN conditions showed TS for post-anthesis Amax. In addition, higher expression than the bread wheat parent was observed for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94 under HN conditions for GY and for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94 under HN conditions for AGDM showing potential to exploit these genotypes for wide crossing for NUE wheat breeding. Seedling root architectural traits including seminal root number per plant showed association with field and glasshouse GY and NUE related traits in HN and LN conditions. Overall amphidiploids showed evidence for increased root depth than bread wheat cultivars in the hydroponics seedling platform under both HN and LN conditions. In summary: • N-use efficiency in thirty Indian wheat cultivars in the field was correlated with onset of flag-leaf senescence under high N and low N conditions and senescence timing was correlated with N accumulation at anthesis. • Yield response to N limitation of 30 wheat cultivars was associated with responses in N uptake at anthesis under both N conditions. • The grain yield in N stressed crops for the 30 cultivars was limited by post-anthesis source capacity. • Three amphidiploids lines (Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94) in glasshouse conditions showed higher flag-leaf photosynthesis rate and prolonged flag leaf green area than their recurrent parents. • The 2D seedling RSAT study showed seminal root number was correlated amongst 12 Indian wheat cultivars and amphidiploids with grain yield per shoot under high and low N conditions

Microvine: an ecophysiological model for grapevine: La micro-vigne : un modèle écophysiologique pour la vigne

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Microvine: A New Model to Study Grapevine Growth and Developmental Patterns and their Responses to Elevated Temperature

Growing standardized plant material in controlled environment can facilitate the disentangling of the many impacts of climate change on grapevine production and quality. Microvine is a natural gibberellic acid insensitive mutant showing dwarfism, early and continuous flowering along the vegetative axes. It was initially proposed as a model for genetics. In this study, we questioned its suitability to facilitate and hasten the characterization of grapevine vegetative and reproductive growth and development patterns as wells as their responses to temperature elevation. A series of experiments were performed in the greenhouse and in growth chambers under either ‘standard’ (25/15°C days/night) or contrasted (from 22/12°C up to 30/25°C) thermal treatments for several weeks. Under ‘standard’ thermal condition, measured temporal patterns of leaf and berry growth were similar among several phytomers along the main axis allowing us to estimate temporal growth patterns from spatial distribution of organ size. These patterns were stable between independent experiments under similar thermal and irradiance conditions. When plants were exposed to contrasted thermal treatments, leaf emergence rate was found linearly related to average daily temperature allowing us to derive a thermal time based model of development. Under cool thermal conditions (22/12°C), the temporal evolution of biochemical parameters was similar to that classically found for grapevine. However, exposing plants to a + 8°C thermal treatment for 450 °Cd revealed strong alterations of the thermal time based developmental program with either acceleration (leaf and internode growth) or delay (flowering, sugar accumulation in berries), as well as major uncoupling between growth and storage in internodes. These results reveal the potential of Microvine to study grapevine responses to the many facets of climate change.Bases développementales, moléculaires et génétiques de l'adaptation de la vigne à la contrainte thermique

Diversity and Adaptation of Currently Grown Wheat Landraces and Modern Germplasm in Afghanistan, Iran, and Turkey

Collection of wheat landraces (WLR) was conducted in Afghanistan, Iran, and Turkey in 2010–2014. A representative subset of this collection was used in the current study and included 45 bread wheat landraces from Turkey, 19 from Iran, and 20 from Afghanistan. This material was supplemented by 73 modern cultivars and breeding lines adapted to semiarid conditions and irrigated conditions. Overall, 157 genotypes were tested in Turkey in 2018 and 2019 and in Afghanistan and Iran in 2019 under rainfed conditions to compare performance of WLR and modern material. The germplasm was genotyped using a high density Illumina Infinium 25K wheat SNP array and KASP markers for agronomic traits. The average grain yield ranged between 2.2 and 4.0 t/ha depending on the site and year. Three groups of landraces demonstrated similar average grain yield, though Afghanistan material was slightly higher yielding not only in Afghanistan but also in Turkey. Modern material outyielded the landraces in two environments out of four. The highest yielding landraces were competitive with the best modern germplasm. Frequency of gene Sus2-2B affecting 1000 kernel weight was 64% in WLR and only 3% in modern material. Presence of positive allele of Sus2-2B increased 1000 kernel weight by nearly 4%. Breeding strategy to improved landraces and modern cultivars is discussed