Can intensification be sustainable?

Contemporary interest in agricultural sustainability can be traced to environmental concerns that began to appear in the 1950s and 1960s. However, concepts and practices about sustainability date back at least to the oldest surviving texts from China, India, Greece and Rome. Today the global challenge is great.

In order to provide sufficient food for growing populations and their changing consumption patterns, some indicate that agriculture will have to expand into non-agricultural lands. However, the competition for land from other human activities makes this a costly solution, particularly if protecting biodiversity and the public goods provided by natural ecosystems (e.g. carbon storage in forests) is given priority. Others suggest that yield increases must be achieved through redoubled efforts to repeat the approaches of the green revolution; or that agricultural systems should embrace only biotechnology or become solely organic. What is clear despite these differences is that more will need to be made of existing agricultural land.

Agriculture in Kenya. Photo: Jules Pretty.

Patch intensification in Kenya. Photo: Jules Pretty.

Agriculture will, in short, have to be intensified. Traditionally agricultural intensification has been defined in three ways: i) increasing yields per hectare, ii) increasing cropping intensity (i.e. two or more crops) per unit of land or other inputs (water), or livestock intensity (e.g. faster maturing breeds), and iii) changing land use from low value crops or commodities to those that receive higher market prices or have better nutritional content.

Mucuna, Photo: Jules Pretty

Mucuna bean crops, Central America. Photo: Jules Pretty

The notion of “intensification” remains controversial to some, as recent successes in increasing food production per unit of resource have often also caused environmental harm and disruption to social systems.

The desire for agriculture to produce more food without environmental harm, or even positive contributions to natural and social capital, has been reflected in calls for a wide range of different types of more sustainable agriculture: for a ‘doubly green revolution’, for ‘alternative agriculture’, for an ‘evergreen revolution’, for ‘agroecological intensification’, for ‘green food systems’, for ‘greener revolutions’, and ‘evergreen agriculture’.

Multiple crops. Photo: Jules Pretty.

Multiple crops, Java. Photo: Jules Pretty.

Sustainable intensification (SI) is defined as a process or system where yields are increased without adverse environmental impact and without the cultivation of more land. The concept is thus relatively open, in that it does not articulate or privilege any particular vision of agricultural production. It emphasises ends rather than means, and does not predetermine technologies, species mix, or particular design components.


Pretty J. & Barucha Z.P. (2014). Sustainable intensification in agricultural systems, Annals of Botany, DOI: http://dx.doi.org/10.1093/aob/mcu205

Novel lineage-specific inversion and legume plastome evolution

Novel lineage-specific inversion and legume plastome evolution

Novel lineage-specific inversion and legume plastome evolution

Complete legume chloroplast genomes are only available for one Papilionoid clade, and information from other lineages is thus needed to better understand this family’s atypical evolution. Martin et al. sequence the plastome of Lupinus luteus, representing the Genistoid lineage, and perform comparative analyses at the structural and sequence levels. They discover a 36-kb inversion, embedded within the already known 50-kb inversion in the large single-copy region of the Papilionoideae. This inversion occurs at the base or soon after the Genistoid emergence, and most likely resulted from a flip-flop recombination. Mutational hotspots are also identified and new potentially informative regions for phylogenetic and molecular evolutionary studies in legumes are detected.

Scientists look for a common language in Himalaya ecology

The Himalaya range of mountains is famous all over the world. This is the world’s largest mountain range with fastest uplift rate hosts enormous physical as well as biological resources. The Himalayan region of Pakistan is actually the well known Western Himalayan Province famous for its unique flora and fauna of endemic and threatened nature. The Himalayas of Pakistan not only preserve the precious biodiversity but also provide precious ecosystem services including supporting, providing and cultural services. The Himalayan highlands of Pakistan provide uncountable environmental benefits and socioeconomics standing to the dwellers of the region. The area is blessed with the world’s highest plateaus, glaciers, snow fields, forests, wildlife and immense unexplored genetic resources.

Mountains of Pakistan

Mountains of Pakistan. Photo: Shujaul Mulk Khan.

To explore ecological issues in the Himalaya region, Hazara University, of Pakistan, is holding what is hoped to be just the first of a series of symposia on conservation issues. This symposium will not only gather the experts to discuss the potential and issue from different points of view but will also provide an opportunity to introduce the area internationally in terms of research and the ecotourism industry.

A trans-disciplinary symposium has the ability to draw together multiple researchers in different fields who might be tackling the same problems in isolation from each other. A recent review in Annals of Botany argued that we should be combining Importance Value Indices (IVIs) based on classifications of species assemblages and environmental biodiversity gradients and Use Values (UVs) that use anthropological methods to examine how local communities use different plants. This could be unexpectedly wide, as the difference in altitude over a small distance means one community could access many different ecological niches.

This local experience adds an important dimension to the accepted biodiversity conservation criteria – rarity, threat and endemism. Species can also have historical, traditional and educational values. These are values that are as much under threat as the plants themselves as urbanism encroaches on local communities, and could be a significant loss. For example ethnomedical knowledge can help recognise and preserve important species. If we do not pay attention to the loss this cultural practice, then its loss might also lead to losing the plant itself and any uses it might have.

The event will be held November 27-30, at Hazara University, Mansehra. The aim of this event will be to introduce the potential and problems of biodiversity and ecosystems of this region and to mitigate the issues through proper involvements of the relevant stakeholders.

Complete outcrossing in a monoecious clonal seagrass

Complete outcrossing in a monoecious clonal seagrass

Complete outcrossing in a monoecious clonal seagrass

Seagrasses are marine, flowering plants with a hydrophilous pollination strategy. Sinclair et al. study microsatellite DNA markers in order to understand the interactions between clonal structure, mating system and pollen dispersal in two seagrass meadows of Posidonia australis with contrasting local environmental conditions, one being exposed and the other being sheltered. The results show that in a system that appears to rely on chance pollination, all embryos are the result of outcrossed pollination. Pollen is thus being mixed in the water column, with local conditions having little influence on the success and pattern of pollination. Complete outcrossing suggests that post-pollination mechanisms may also be in place to prevent geitonogamous selfing.

Microgravity and chromosome damage

The Karyological Observations of Krikorian and O’Connor look at plant material from flights STS-2 and STS-3 of the Space Shuttle.

STS-2, among other things, carried a payload of Helianthus annuus, sunflowers. STS-2 was cut short from five days to two when a fuel cell for producing electricity and processing water failed. Despite this the plants had some time to grow, in a couple of cases with roots protruding from the soil. Krikorian and O’Connor say: “The soil environment of the roots in the HEFLEX-type modules was not particularly well suited to recovery of roots tips for karyological examination.” In plain English it sounds like it was extremely difficult, and they go on in the paper to explain some of the problems they had.

The key result was that when they looked at the cells, they found only around 2% were in division. The same plant in a lab would be expected to be ten times more active. They also found some plants had aneuploidy. Usually chromosomes come in pairs, (though polyploidy is common in plants too). In this case one plant was missing a partner for chromosome 6. The same was true in another plant from the sample. Given these results, similar tests followed on the STS-3 material.

Again with the oats, it was found that only a 2% of cells were in division, again about ten times less than anticipated from the lab. There was also chromosome damage. The mung beans too were found to have low counts for division, though less obvious signs of damage to the chromosomes.

It seems something was affecting the plants, but in their conclusions Krikorian and O’Connor were wary of saying exactly what. The obvious suspect is microgravity, but they also left open the possibility that it was the effect of launch and/or re-entry that was the problem. It’s this referring back to the control that marks out the value of the research on STS-3. It wasn’t simply that material was put into orbit, it was also that the same equipment was run on the ground to act as a control. If gravity is the variable you’re changing then it’s essential to get as much of the rest of the control experiment to run as closely to the orbital experiment as possible.

Like some of the other papers in this supplement, Karyological Observations has been cited this year in a paper Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity published October 2014 in Astrobiology. Link et al. also cite Kuang et al from 1996, Musgrave et al from 1998 and Kuang et al from 2000. In some ways it might be surprising that work from thirty years ago is still getting cited, but that’s how science works.

Currently NASA does plant science in orbit on the International Space Station, but this latest platform was built with the shuttle and the aging Russian Soyuz craft. In a similar way current plant research is built on the prior work of earlier scientists. Fortunately you don’t have to wait thirty years to see most research in Annals of Botany. If your library doesn’t have access to the journal, papers become free access a year after paper publication.

Space Shuttle landing

STS-3 lands at White Sands. Photo: NASA.

You can read more posts on papers from our spaceflight supplement by clicking the STS-3 tag.

Today’s Papers

Krikorian A.D. & O’Connor S.A. Karyological Observations, Annals of Botany, 54 (supp3) 49-63. DOI:

KUANG A. (1996). Cytochemical Localization of Reserves during Seed Development inArabidopsis thalianaunder Spaceflight Conditions, Annals of Botany, 78 (3) 343-351. DOI: http://dx.doi.org/10.1006/anbo.1996.0129

Kuang A. (2000). Influence of Microgravity on Ultrastructure and Storage Reserves in Seeds of Brassica rapa L., Annals of Botany, 85 (6) 851-859. DOI: http://dx.doi.org/10.1006/anbo.2000.1153

Link B.M. & Bratislav Stankovic (2014). Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity , Astrobiology, 14 (10) 866-875. DOI: http://dx.doi.org/10.1089/ast.2014.1184

MUSGRAVE M. (1998). Changes inArabidopsisLeaf Ultrastructure, Chlorophyll and Carbohydrate Content During Spaceflight Depend on Ventilation, Annals of Botany, 81 (4) 503-512. DOI: http://dx.doi.org/10.1006/anbo.1998.0585

Polyploidy and long-distance dispersal

Polyploidy and long-distance dispersal

Polyploidy and long-distance dispersal

Most of the numerous and remarkable range disjunctions across the southern oceans are probably the result of occasional long-distance dispersal, rather than of vicariance. Linder and Barker study the grass subfamily Danthonioideae, which probably reached its current global distribution by a number of long-distance dispersal events during the Neogene, and show that such dispersal is much more likely in polyploid than in diploid species. It is possible that polyploidy facilitates post-dispersal establishment, and it is postulated that the frequent occurrence of polyploidy in the grasses may thus have facilitated their long-distance dispersal, and hence contributed to the remarkable success of the family.

Use it or lose it, for a plant’s sense of gravity?

Gravitropism is the ability of a plant to turn in response to gravity. Roots have gravitropism, bending to turn down and stems negative gravitropism to turn up. But what happens if you remove a plant’s ability to sense where down is?

In roots, plants feel where down is in the root cap. If you remove the root cap carefully, and then tip the plant on its side, the root will continue to grow without changing direction until the root cap regenerates. Once the root cap can signal to the root, cells on one side of the root elongate to bend the root downwards.

The flight of STS-3 posed a challenge to the plants on board. Once in orbit they would be in perpetual freefall and there’d be no sense of ‘up’. What effect would this have on the root cap? Slocum, Gaynor and Galston compared the responses of the oat and mung bean seedlings on board in their paper Cytological and Ultrastructural Studies on Root Tissues. Seedlings for both plants germinated either a few hours before launch or in orbit.

The oats were fine. Both the flight and ground-based oat seedlings had normal root structure. The same was almost true for the mung beans too. Most of the roots were normal, except for the root-cap in the flight sample. The root cap cells on the mung beans in space had had a very bad time. Most of the cells were degenerated. If you compare the control sample below (left) with the flight root (right) you can see one of them is not well.

Two roots, the one on the right looking terrible.

Light micrographs of A, ground control and B, flight-grown mung bean roots, seen in near
median longitudinal section x 75.

It seems that the ability of plants to adapt to microgravity varies on the plant, so it’s not enough to extrapolate from one to all.

This is another paper that continues to get cited today. Most recently Simple sequence repeat markers reveal multiple loci governing grain-size variations in a japonica rice (Oryza sativa L.) mutant induced by cosmic radiation during space flight by Wang et al in Euphytica 2014. There’s also research on peas citing it like Ultrastructure and metabolic activity of pea mitochondria under clinorotation in Cytology and Genetics 2012.

If gravity is essential, then it might become something we have to fake in space. The usual idea is to gently rotate a space station to give a sense of centripetal force. Spin faster and it is possible to subject plants to hypergravity, as noted by Nigel Chaffey earlier this year. Perennial favourite Arabidopisis is the subject of a 300g (yes, three hundred times the force of gravity) in this paper from AnnBot. Subjecting humans to this level of gravity would be a Very Bad Idea.

You can read more posts on papers from our spaceflight supplement by clicking the STS-3 tag.

Today’s Papers

Slocum R.D., Gaynor J.J. & Galston A.W. (1984). Cytological and Ultrastructural Studies on Root Tissues, Annals of Botany, 54 (supp3) 65-76.

Brykov V.O. & I. P. Generozova (2012). Ultrastructure and metabolic activity of pea mitochondria under clinorotation, Cytology and Genetics, 46 (3) 144-149. DOI: http://dx.doi.org/10.3103/s0095452712030036

NAKABAYASHI I. (2006). Hypergravity Stimulus Enhances Primary Xylem Development and Decreases Mechanical Properties of Secondary Cell Walls in Inflorescence Stems of Arabidopsis thaliana, Annals of Botany, 97 (6) 1083-1090. DOI: http://dx.doi.org/10.1093/aob/mcl055

Wang J., Tianqing Zheng, Xiuqin Zhao, Jauhar Ali, Jianlong Xu & Zhikang Li (2013). Simple sequence repeat markers reveal multiple loci governing grain-size variations in a japonica rice (Oryza sativa L.) mutant induced by cosmic radiation during space flight, Euphytica, 196 (2) 225-236. DOI: http://dx.doi.org/10.1007/s10681-013-1026-8

Rapid divergence of ecotypes of an invasive plant

14058S1R2Invasive species represent examples of rapid evolutionary change in a relatively short time period. Lantana camara, a well known invasive plant in the tropics and sub-tropics that has expanded its range and successfully established almost throughout India, is a suitable model system to study the mechanisms underlying its rapid spread and evolution. In a new study in AoB PLANTS, Ray and Ray employed population genetics tools and found differential spread of two genetic varieties across the Indian landscape. Varieties also differ in terms of their climatic adaptation and gene flow, indicating possible local adaptation. Together, this may suggest that these varieties are divergent ecotypes at very early stages of differentiation.

Is there a downside for plants when they can’t sense ‘up’?

Looking at a tree, it can be hard to visualise the sheer volume of water being drawn up from the roots to the canopy. That volume of was is massive, and puts cells under a lot of pressure, so lignin, the substance plants use to strengthen cell walls, is an important product. But what happens to lignin if you take gravity away? Growth and Lignification in Seedlings Exposed to Eight Days of Microgravity by Cowles et al. is a study that aims to find out.

The experiment on STS-3 was growing pine seedlings with mung beans and oat seeds. There were a couple of targets. One was to examine how gravity affected the production of lignin. The other was to test the PGU, the plant growth unit, that would be used in following missions.

Plant Growth Unit

From Cowles et al.

To see the effect of gravity a PGU with similar plants was kept on Earth, so the development of the plants could be compared.

Germination of the orbiting plants was much like the 1g plants. However, Cowles et al. point out that the seeds have to be prepared before launch, which gave them twelve hours on Earth to germinate. They found that the flying plants grew less, and in the case of the seeds, roots were growing ‘up’ as well as ‘down’. Some of the plants that grew in orbit also contained less lignin.

There have been plenty of papers that went on to cite this research, most recently Expression of stress-related genes in zebrawood (Astronium fraxinifolium, Anacardiaceae) seedlings following germination in microgravity by Inglis et al. in Genetics and Molecular Biology from this year.

Recently in Annals of Botany there’s been Xylem Development and Cell Wall Changes of Soybean Seedlings Grown in Space and in the opposite directon Hypergravity Stimulus Enhances Primary Xylem Development and Decreases Mechanical Properties of Secondary Cell Walls in Inflorescence Stems of Arabidopsis thaliana by Nakabayashi et al.

This is interesting that it still gets cited because the results weren’t all significant. While the mung beans had less lignin, the oat and pine seedlings didn’t have significantly less and the experiment was relatively small. However, this flight wasn’t just about the results, it also worked to establish a method. By laying out the experimental technique used to analyse the plant Cowles et al laid down a baseline for other researchers to compare and improve their techniques.

The basic question they studied remains important. Understanding the processes that produce lignin could help with technology on Earth. For example, it would be helpful in producing biofuel if there were less lignin in it to start with. Launching plants and growing them in space would be a spectacularly inefficient way to do that. However for small samples, it can be a useful way to isolate one variable and help figure out the mechanics of lignin production.

You can read more posts on papers from our spaceflight supplement by clicking the STS-3 tag.

Today’s Papers

Cowles J.R., Scheld H.W., Lemay R. & Peterson C. (1984). Growth and Lignification in Seedlings Exposed to Eight Days of Microgravity , Annals of Botany, 54 (supp3) 33-48. DOI:

Chapple C. & Rick Meilan (2007). Loosening lignin’s grip on biofuel production, Nature Biotechnology, 25 (7) 746-748. DOI: http://dx.doi.org/10.1038/nbt0707-746

de Micco V., J.-P. Joseleau & K. Ruel (2008). Xylem Development and Cell Wall Changes of Soybean Seedlings Grown in Space, Annals of Botany, 101 (5) 661-669. DOI: http://dx.doi.org/10.1093/aob/mcn001

Inglis P.W., Ciampi A.Y., Salomão A.N., Costa T.D.S.A. & Azevedo V.C.R. (2013). Expression of stress-related genes in zebrawood (Astronium fraxinifolium, Anacardiaceae) seedlings following germination in microgravity., Genetics and molecular biology, PMID: http://www.ncbi.nlm.nih.gov/pubmed/24688295

NAKABAYASHI I. (2006). Hypergravity Stimulus Enhances Primary Xylem Development and Decreases Mechanical Properties of Secondary Cell Walls in Inflorescence Stems of Arabidopsis thaliana, Annals of Botany, 97 (6) 1083-1090. DOI: http://dx.doi.org/10.1093/aob/mcl055

Transgenerational changes in seed longevity in Silene

Transgenerational changes in seed longevity in <i>Silene</i>

Transgenerational changes in seed longevity in Silene

Seed longevity, a fundamental plant trait for ex situ conservation and persistence in the soil of many species, varies across populations and generations that experience different climates. Mondoni et al.  study seeds from alpine and lowland populations of Silene vulgaris and show that seed longevity has a genetic basis but may show strong adaptive responses, which are associated with differential accumulation of mRNA via parental effects. They conclude that adaptive adjustments of seed longevity due to transgenerational plasticity may play a fundamental role for the survival and persistence of the species in the face of future environmental challenges, and that the location of regeneration may have important implications for ex situ conservation in seed banks.