Contribution of NFP LysM Domains to the Recognition of Nod Factors during the Medicago truncatula/Sinorhizobium meliloti Symbiosis

The root nodule nitrogen fixing symbiosis between legume plants and soil bacteria called rhizobia is of great agronomical and ecological interest since it provides the plant with fixed atmospheric nitrogen. The establishment of this symbiosis is mediated by the recognition by the host plant of lipo-chitooligosaccharides called Nod Factors (NFs), produced by the rhizobia. This recognition is highly specific, as precise NF structures are required depending on the host plant. Here, we study the importance of different LysM domains of a LysM-Receptor Like Kinase (LysM-RLK) from Medicago truncatula called Nod factor perception (NFP) in the recognition of different substitutions of NFs produced by its symbiont Sinorhizobium meliloti. These substitutions are a sulphate group at the reducing end, which is essential for host specificity, and a specific acyl chain at the non-reducing end, that is critical for the infection process. The NFP extracellular domain (ECD) contains 3 LysM domains that are predicted to bind NFs. By swapping the whole ECD or individual LysM domains of NFP for those of its orthologous gene from pea, SYM10 (a legume plant that interacts with another strain of rhizobium producing NFs with different substitutions), we showed that NFP is not directly responsible for specific recognition of the sulphate substitution of S. meliloti NFs, but probably interacts with the acyl substitution. Moreover, we have demonstrated the importance of the NFP LysM2 domain for rhizobial infection and we have pinpointed the importance of a single leucine residue of LysM2 in that step of the symbiosis. Together, our data put into new perspective the recognition of NFs in the different steps of symbiosis in M. truncatula, emphasising the probable existence of a missing component for early NF recognition and reinforcing the important role of NFP for NF recognition during rhizobial infection

Toward sustainable coffee production in Vietnam: more coffee with less water

Inefficient use of irrigation water threatens coffee production in Vietnam, the second largest producer worldwide after Brazil. This paper examines the irrigation issues that constrain sustainable coffee production in Vietnam. The period from January to April is a crucial time in the growth of the coffee crop. It requires irrigation, because rainfall only provides 25% of the potential crop evapotranspiration demand. According to crop phenology, this period also requires induced water stress, because it coincides with breaking the dormancy of flower buds and initiation of cherry development, which is crucial for achieving high yield. This paper proposes an irrigation supply of 120 or 150 mm between January and April in a year preceded by good or average rainfall respectively, in November and December. This is equivalent to 364 or 456 liters/plant/round in 3 rounds/year, which is only 70% of the locally recommended level by the Ministry of Agriculture and Rural Development. Synchronizing this irrigation supply with the management of other inputs could increase average yield up to 4000 kg/ha, from the present level of 2400 kg/ ha making coffee production both sustainable and economically viable. In order to achieve this, building capacity of farmers to follow the irrigation and input application schedules is crucial

Towards sustainable coffee production in Vietnam: addressing irrigation issues. Vietnam Project

Inefficient use of groundwater perils Vietnamﾒs coffee production, the second largest of the world after Brazil. Unsustainable coffee production in Vietnam has both national and global ramifications. Nationally, it is so crucial that coffee is the second largest export-earning crop after rice, and the production supports livelihoods of significant rural agricultural population with small land holdings. Internationally, Vietnamﾒs coffee exports meet the rapidly growing demand, and account 19% of worldﾒs coffee exports in 2010, up from only 2% in 1990. This paper examines groundwater irrigation issues that constraint sustainable coffee production in Vietnam. January to April is a crucial period of coffee crop growth: it requires irrigation, because rainfall meets only 25% of the potential crop-evapotranspiration demand. According to crop phenology, this period also requires induced water stress, because it coincides with breaking the dormancy of coffee buds and initiation of cherry development, which is crucial for higher yield. The paper recommends irrigation supply of 120 to 150 mm/ha between January and April in a year preceded by good or average rainfall respectively in November and December. This is equivalent to 456 liters/plant/round in 3 rounds/year, which is a significant reduction from the recommend level of 650 liters/plant/round. Synchronizing this irrigation supply with other inputs could increase average yield up to 4,000 kg/ha, from the present level of 2,400 kg/ha. These require experimental studies to understand the timings of irrigation rounds and other inputs, capacity building of farmers to follow the irrigation and input application schedules, and public awareness campaigns to raise the importance of improved irrigation management methods

Biosynthesis of Azorhizobium caulinodans Nod factors. Study of the activity of the NodABSC proteins by expression of the genes in Escherichia coli

International audienc

Environmental consequences of the demise in swidden cultivation in montane mainland southeast asia: Hydrology and geomorphology

10.1007/s10745-009-9258-xHuman Ecology373361-37