Artificial selection of the Green Revolution gene Semidwarf 1 is implicated in upland rice breeding

Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.

Sawah Rice Eco-technology and Actualization of Green Revolution in West Africa: Experience from Nigeria and Ghana

The development and dissemination of sawah rice eco-technology in Nigeria and Ghana as prerequisites for the actualization of green revolution in West Africa were described. It showed that the neglect of the eco-technology and the overemphasis of the biotechnology have rendered the ineffective transferability of the green revolution process from Asia to Africa. The sawah eco-technology increases yield up to 5 t/hm2 through bunding and the use of inlet and outlet connecting irrigation and drainage, which enhances effective water control and management, improves the efficiency of fertilizer, improves nitrogen fixation by soil microbes and algae, increases the use of wetlands, improves soil organic matter accumulation, suppresses weed growth, and enhances immune mechanism of rice through nutrient supply. The current experience has therefore established that the technology overcomes the constraints that have limited the realization of green revolution in West Africa.

Coordinating gibberellin and brassinosteroid signaling beyond Green Revolution

The Green Revolution,which took place in the 1960s,was instrumental in increasing grain yields and mitigating the world’s food crisis.Breeding semi-dwarfing crops was a critical activity that significantly improved lodging resistance,field management,and harvesting convenience.Subsequent molecular genetic studies revealed that the semi-dwarfing genes used in rice and wheat,two major staple crops,are related to the plant hormone gibberellin(GA).In rice,SD1 encodes a defective GA synthetic enzyme GA20ox-2,while in wheat,Rht-1(Rht-B1b or Rht-D1b)encodes the gain-of-function form of the GA signaling inhibitors known as DELLA proteins(Peng et al.,1999;Sasaki et al.,2002).However,defects in either GA synthesis or signaling can decrease nitrogen use efficiency(NUE)and potentially lead to inferior grain development.Ultimately,the success of the Green Revolution relies heavily on the massive input of nitrogen fertilizer,which causes severe environmental issues.

A Strigolactone Biosynthesis Gene Contributed to the Green Revolution in Rice

Plant architecture is a complex agronomic trait and a major factor of crop yield,which is affected by several important hormones.Strigolactones(SLs)are identified as a new class hormoneinhibiting branching in many plant species and have been shown to be involved in various developmental processes.Genetical and chemical modulation of the SL pathway is recognized as a promising approach to modify plant architecture.However,whether and how the genes involved in the SL pathway could be utilized in breeding still remain elusive.Here,we demonstrate that a partial loss-of-function allele of the SL biosynthesis gene,HIGH TILLERING AND DWARF 1/DWARF17(HTD1/D17),which encodes CAROTENOID CLEAVAGE DIOXYGENASE 7(CCD7),increases tiller number and improves grain yield in rice.We found that the HTD1 gene had been widely utilized and co-selected with Semidwarf 1(SD1),both contributing to the improvement of plant architecture in modern rice varieties since the Green Revolution in the 1960s.Understanding how phytohormone pathway genes regulate plant architecture and how they have been utilized and selected in breeding will lay the foundation for developing the rational approaches toward improving crop yield.

Toward a “Green Revolution” for Soybean

Soybean(Glycine max),as an economically important food and oilseedcrop,is a major source of plant proteins and oils.Although considerable progress has been made in increasing the yields of rice,wheat,and maize through the“Green Revolution”,little improvements have been made for soybean.With the increasing demand of soybean production and the rapid development of crop breeding technologies,time has come for this important crop to undergo a Green Revolution.Here,we briefly summarize the history of crop breeding and Green Revolution in other crops.We then discuss the possible directions and potential approaches toward achieving a Green Revolution for soybean.We provide our views and perspectives on how to breed new soybean varieties with improved yield.

N-terminal truncated RHT-1 proteins generated by translational reinitiation cause semi-dwarfing of wheat Green Revolution alleles

The unprecedented wheat yield increases during the Green Revolution were achieved through the introduc-tion of the Reduced height(Rht)-B1b and Rht-D1b semi-dwarfing alleles.These Rht-1 alleles encode growth-repressing DELLA genes containing a stop codon within their open reading frame that confers gibberellin(GA)-insensitive semi-dwarfism.In this study,we successfully took the hurdle of detecting wild-type RHT-1 proteins in different wheat organs and confirmed their degradation in response to GAs.We further demonstrated that Rht-B1b and Rht-D1b produce N-terminal truncated proteins through trans-lational reinitiation.Expression of these N-terminal truncated proteins in transgenic lines and in Rht-D1c,an allele containing multiple Rht-D1b copies,demonstrated their ability to cause strong dwarfism,resulting from their insensitivity to GA-mediated degradation.N-terminal truncated proteins were detected in spikes and nodes,but not in the aleurone layers.Since Rht-B 1b and Rht-D1b alleles cause dwarfism but have wild-type dormancy,this finding suggests that tissue-specific differences in translational reinitiation may explain why the Rht-1 alleles reduce plant height without affecting dormancy.Taken together,our findings not only reveal the molecular mechanism underlying the Green Revolution but also demonstrate that trans-lational reinitiation in the main open reading frame occurs in plants.

Towards Second Green Revolution: Engineering Nitrogen Use Efficiency

Gaseous nitrogen （N2） makes up 78% of the earth＇s at- mosphere; its incorporation into a wide range of biological macromolecules molecules, such as nucleic acids and amino acids, makes it an essential part of all life on earth. However, as nitrogen gas is inert, it remains unavailable to most organisms, including plants. Thus, in order to be useful for fertilizer production, gaseous nitrogen needs first to be converted into bioavailable organic nitrogen in processes which are inefficient and rate-limiting for agricultural pro- duction. It was not until about 100 years ago that BASF were able to produce synthetic ammonia, the main ingredient for fertilizer production, on an industrial scale from pressurized air using the Haber--Bosch process. This chemical process was not only an impressive technical feat that helped Haber （1918） and Bosch （1931） earn Nobel Prizes but also enabled farmers to achieve the high yields that drive modern agriculture.

Green Revolution on the Loess Plateau

THE Workers’ and Peasants’ Red Army, under the leadership of the Communist Party of China(CPC), arrived in northern Shaanxi Province at the end of 1935 following an arduous journey of over 12,500 km. Survivors of the Long March settled in the small bleak and desolate city ofYan’an.

Rational management of the plant microbiome for the Second Green Revolution

The Green Revolution of the mid-20th century transformed agriculture worldwide and has resulted in envi-ronmental challenges.A new approach,the Second Green Revolution,seeks to enhance agricultural pro-ductivity while minimizing negative environmental impacts.Plant microbiomes play critical roles in plant growth and stress responses,and understanding plant–microbiome interactions is essential for developing sustainable agricultural practices that meet food security and safety challenges,which are among the United Nations Sustainable Development Goals.This review provides a comprehensive exploration of key deterministic processes crucial for developing microbiome management strategies,including the host effect,the facilitator effect,and microbe–microbe interactions.A hierarchical framework for plant mi-crobiome modulation is proposed to bridge the gap between basic research and agricultural applications.This framework emphasizes three levels of modulation:single-strain,synthetic community,and in situ mi-crobiome modulation.Overall,rational management of plant microbiomes has wide-ranging applications in agriculture and can potentially be a core technology for the Second Green Revolution.

Global Climate Change and China's Green Development

For China, green industrial revolution induced by global climate change poses not only the greatest challenge, but also the greatest opportunity. In the perspective of China's basic national conditions, and especially its natural conditions, China's green development is the inevitable path of choice for the realization of sustainable development and scientific development. The essence of China's modernization 2050 is green modernization, taking the three-step strategy towards China's own green development and energy conservation and emission reduction. In combination with the 12 th Five Year Plan, its innovative positioning is "green development plan".

Cloning of a new allele of ZmAMP1 and evaluation of its breeding value in hybrid maize

Gene resources associated with plant stature and flowering time are invaluable for maize breeding.In this study,using an F2:3population derived from a natural semi-dwarf mutant grmm and a normal inbred line Si 273,we identified a major pleiotropic QTL on the distal long arm of chromosome 1(qPH1_dla),and found that qPH1_dla controlled plant height,flowering time,ear and yield traits.qPH1_dla was finemapped to a 16 kb interval containing ZmAMP1,which was annotated as a glutamate carboxypeptidase.Allelism tests using two independent allelic mutants confirmed that ZmAMP1 was the causal gene.Realtime quantitative PCR and genomic sequence analysis suggested that a nonsynonymous mutation at the598th base of ZmAMP1 gene was the causal sequence variant for the dwarfism of grmm.This novel ZmAMP1 allele was named ZmAMP1_grmm.RNA sequencing using two pairs of near isogenic lines(NILs)showed that 84 up-regulated and 68 down-regulated genes in dwarf NILs were enriched in 15metabolic pathways.Finally,introgression of ZmAMP1_grmm into Zhengdan 958 and Xianyu 335 generated two improved F1lines.In field tests,they were semi-dwarf,early-flowering,lodging-resistant,and high-yielding under high-density planting conditions,suggesting that ZmAMP1_grmm is a promising Green Revolution gene for maize hybrid breeding.

How United States Agricultural Herbicides Became Military and Environmental Chemical Weapons: Historical and Residual Effects

Discoveries in Charles Darwin’s laboratory led to modern herbicides. Darwin discovered the internal mechanism that directed plants to grow toward sunlight and sources of water. Scientists in Europe and America later called this mechanism a plant’s hormone response system. Administrators and scientists, including Dr. Ezra J. Kraus, the Head of the Botany Department at the University of Chicago and a plant physiologist, suggested on the eve of WWII that weed killers had significant military value as chemical weapons. Dr. Kraus obtained access to a synthetic chemical, 2,4-D, and found that when the chemical was absorbed through the leaves of plants, it destroyed a plant’s hormones. After exposure, the plant experienced rapid and uncontrolled growth, and then the leaves shriveled, died and fell off. Dr. Kraus obtained funding for his Department of Botany research program from Department of Defense (DOD) during World War II (WWII). Camp Detrick (Biological Weapons Laboratory) scientists later obtained samples of newly created 2,4,5-T which contained unknown amounts of the by-product dioxin TCDD. In the 1950s and 1960s, Fort Detrick military scientists formulated the herbicide Agent Orange, which was a 50 - 50 mixture of 2,4-D and 2,4,5-T. These dual purpose herbicides were used by DOD and USDA. American and European farmers in the 1940s used 2,4-D and 2,4,5-T to eliminate weeds from pastureland and cropland. After WWII, synthetic herbicides (and pesticides) development continued in tandem with production of synthetic fertilizers and breeding of high-yield plant varieties. These new agricultural products were then shipped worldwide to increase crop yields, as part of the Green Revolution. This new system of agricultural technologies was intended to eliminate global starvation and increase food security by increasing field and farm crop yields. In contrast, the goal of military use of herbicides, as chemical weapons, was to defoliate jungle forests and destroy food crops as a strategy to win battles and wars. The primary objective of this research study is to describe how agricultural herbicides became tactical chemical weapons. A current assessment will address the environmental impacts of military and environmental chemical weapons on the United States and Vietnam ecosystems and need for additional dioxin TCDD hotspot clean-up efforts.

The Poor Agricultural System in Africa, Who Is to Blame?

Although agriculture is the backbone of the African economy, it has faced considerable challenges in the past sixty years. Africa has moved from being a self-sufficiency continent before the 1960s, to net food importers, with a handful of countries facing severe food shortages from drought, desertification, climate change and wars. In this article, we use the case of Northern Ghana to explore some of the salient dynamics that have resulted in the current crisis in the African agricultural sector over time. Using historical and contemporary evidence gathered from Northern Ghana during several field trips from 2013 to 2015, we argue that practices adopted as a result of colonial influence in combination with socio-economic and biophysical factors and ineffective economic policies have contributed immensely to the poor state of agriculture in Africa. Note should be taken that most of these economic policies have origins from the Structural Adjustment Policies and the Poverty Reduction Strategy Papers. We conclude that our agricultural systems can be improved if policies are inclusive, equitable and sustainable and also if there are synergies between international or government organisations implementing agricultural projects over time and space.

Genetic improvement toward nitrogen-use efficiency in rice: Lessons and perspectives

The indispensable role of nitrogen fertilizer in ensuring world food security together with the severe threats it poses to the ecosystem makes the usage of nitrogen fertilizer a major challenge for sustainable agriculture.Genetic improvement of crops with high nitrogen-use efficiency(NUE)is one of the most feasible solutions for tackling this challenge.In the last two decades,extensive efforts toward dissecting the variation of NUE-related traits and the underlying genetic basis in different germplasms have been made,and a series of achievements have been obtained in crops,especially in rice.Here,we summarize the approaches used for genetic dissection of NUE and the functions of the causal genes in modulating NUE as well as their applications in NUE improvement in rice.Strategies for exploring the variants controlling NUE and breeding future crops with“less-input-more-output”for sustainable agriculture are also proposed.

Improving coordination of plant growth and nitrogen metabolism for sustainable agriculture

The agricultural green revolution of the 1960s boosted cereal crop yield was in part due to cultivation of semi-dwarf green revolution varieties.The semi-dwarf plants resist lodging and require high nitrogen(N)fertilizer inputs to maximize yield.To produce higher grain yield,inorganic fertilizer has been overused by Chinese farmers in intensive crop production.With the ongoing increase in the food demand of global population and the environmental pollution,improving crop productivity with reduced N supply is a pressing challenge.Despite a great deal of research efforts,to date only a few genes that improve N use efficiency(NUE)have been identified.The molecular mechanisms underlying the coordination of plant growth,carbon(C)and N assimilation is still not fully understood,thus preventing significant improvement.Recent advances have shed light on how explore NUE within an overall plant biology system that considered the co-regulation of plant growth,C and N metabolisms as a whole,rather than focusing specifically on N uptake and assimilation.There are several potential approaches to improve NUE discussed in this review.Increasing knowledge of how plants sense and respond to changes in N availability,as well as identifying new targets for breeding strategies to simultaneously improve NUE and grain yield,could usher in a new green revolution.

Sustainable intensification of agriculture in Africa

Sustainable intensification is a key component of agricultural development in Africa,urgently needed to wean the continent off foreign food supply and to limit agricultural farmland expansion.It is expected that a relatively small fraction of farmers will adopt fertilizer technology,as profits in current economic settings are relatively small while risks are considerable with varying prices and uncertain yield responses.Many smallholders depend on off-farm income and local markets for food supply.Structural adjustments are therefore needed to allow management of larger units of land by trained farmers willing to take this opportunity,while recognizing land right sensitivities.There are large opportunities for African commodity crops to improve food security,including cassava and East African highland banana that strongly respond to fertilizer with limited environmental risks under good management.This requires investments in better functioning markets,local fertilizer production facilities that can produce regional crop blends and cost-efficient distribution networks,providing balanced fertilizers for African farmers.