Etiology of wilt and basal rot of Jatropha curcas in Arriaga, Chiapas, Mexico. Salazar-Pinacho 1. Rosales-Esquinca 1. In the municipality of Arriaga, Chiapas, the death of physic nut Jatropha curcas L. The objective of this study was to determine the causal agent of the physic nut death. The isolates obtained were purified and subjected to biochemical and hypersensitivity tests on tobacco Nicotiana tabacum cv.
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Jatropha curcas L. Jatropha , a shrub species of the family Euphorbiaceae, has been recognized as a promising biofuel plant for reducing greenhouse gas emissions. However, recent attempts at commercial cultivation in Africa and Asia have failed because of low productivity. It is important to elucidate genetic diversity and relationship in worldwide Jatropha genetic resources for breeding of better commercial cultivars.
Here, genetic diversity was analyzed by using accessions from Mesoamerica, Africa and Asia, based on 59 simple sequence repeat markers and eight retrotransposon-based insertion polymorphism markers. We found that central Chiapas of Mexico possesses the most diverse genetic resources, and the Chiapas Central Depression could be the center of origin. We identified three genetic groups in Mesoamerica, whose distribution revealed a distinct geographic cline.
One of them consists mainly of accessions from central Chiapas. This suggests that it represents the original genetic group. We found two Veracruz accessions in another group, whose ancestors might be shipped from Port of Veracruz to the Old World, to be the source of all African and Asian Jatropha.
Our results suggest the human selection that caused low productivity in Africa and Asia, and also breeding strategies to improve African and Asian Jatropha. Cultivars improved in the productivity will contribute to expand mass commercial cultivation of Jatropha in Africa and Asia to increase biofuel production, and finally will support in the battle against the climate change.
Jatropha is a shrub that produces non-edible seed oil suitable for biodiesel fuel. Jatropha has a potential to reduce the consumption of fossil fuel and carbon dioxide emissions Bailis and Baka, ; Bahadur et al. Jatropha is drought tolerant, thereby its biofuel production could avoid competition with food crops Fairless, ; Bahadur et al. Saving of carbon emissions depends on how biofuels are produced.
Large Jatropha plantations have been planned worldwide, particularly in the semiarid and arid areas of African and Asian countries by using seeds derived from local plants Fairless, ; Von Maltitz and Setzkorn, Many commercial plantations, however, have not resulted in as high yields as were anticipated because of the limited productivity Sanderson, ; Singh et al.
Breeding high-yielding Jatropha varieties is in its infancy so far Divakara et al. The low genetic diversity of African and Asian accessions has limited the potential for successful breeding by using local resources.
The challenge now is to develop well-adapted, high-yielding varieties that are suitable for a wide range of climate conditions in African and Asian countries, since only wide plantation with high oil-production can guarantee a good supply for biofuel.
Characterization and preservation of a diverse collection of Jatropha accessions, including those from Mesoamerica, is the key step to develop them. Mesoamerica, especially Mexico, has been shown to possess high genetic variations of Jatropha and was assumed to be its place of origin Makkar and Becker, ; Dias et al.
Mexico has not only toxic Jatropha varieties, but also non-toxic ones, suggesting that Mexico might be also the domestication center of Jatropha Dias et al. Recent studies described that Chiapas, the southernmost state of Mexico bordering Guatemala, might be the center of Jatropha biodiversity Ovando Medina et al. However, a comprehensive study is required to obtain more evidences for this conclusion.
It has been widely approved that Jatropha was brought by Portuguese from Mesoamerica to Cape Verde Islands, and then brought to Africa and Asia Heller, , while the transmission route in Mesoamerica is unknown and the genetic background of African and Asian Jatropha in the world population remains unclear. To improve the traits in the breeding goal of Jatropha in Asia and Africa, it is of great significance not only to identify diverse genetic resources but also to unveil the ancestral genotype of African and Asian Jatropha when shipped from Mesoamerica.
We also evaluated the genetic variability of accessions from each of nine regions in Chiapas, to identify the center of origin. We further identified the voyage from Chiapas to the Old World by tracing the progenies in Mesoamerica sharing the same ancestors with nowadays African and Asian accessions.
Human selection causing a low genetic basis in Africa and Asia is discussed. Finally, we propose strategies to improve African and Asian Jatropha, in order to increase the phenotypic performance including productivity, which will lead us to relieve from the climate change by mass production of the biofuel.
A worldwide collection of Jatropha accessions in this study consisted of accessions from Mesoamerica from Mexico and nine from Guatemala , seven from Africa, and 32 from Asia Supplementary Table 1; see Figure 3 for the locations of Mexican states and regions in the state of Chiapas.
Twenty-one Vietnamese accessions were obtained from plants grown in Quang Tri Province. Sudanese and Egyptian accessions were obtained from the University of Khartoum and University of Sadat City, respectively.
Other accessions were the same as those used in our previous study Sato et al. Jatropha sampling and transferring to Japan were performed in compliance with the Nagoya agreement. Over SSR markers were developed by designing primer pairs surrounding SSR sequences identified by the genomic database of Asian accessions based on our whole genome sequencing project Sato et al.
Effective markers were selected from them based on clear polymorphisms and low number of null alleles. Eight RBIP markers employed in this study were developed from members of the copia-type families identified in the genomic database Alipour et al. All of them were expected to have retrotransposed more recently than other members. Retrotransposon insertion at each locus was shown by combining primers designed from the FLK sequences at both sides and primers designed from LTR sequences.
The DNA samples were diluted to a final concentration of 0. Amplified bands were stained with ethidium bromide. For markers that showed ambiguous bands, experiments were repeated until clear bands were observed by increasing annealing temperatures.
All data analyses were performed based on the genotype data matrix. Expected heterozygosity H E and observed heterozygosity H O show the portion of heterozygotes in populations. They are measures of the extent of genetic variation in a population. H O is heterozygosity at the observed level. Differences between H E and H O are caused by inbreeding often as results of selection or the small population size. Inbreeding coefficient F IS is the value to estimate the level of inbreeding of the population.
The larger F IS shows the larger extent of inbreeding in a population. Comparisons of the significances of H E and H O among populations were performed using Kruskal—Wallis one-way analysis of variance. The final results were shown as a three-dimensional plot X, Y, and Z represent the three principal coordinates of all the accessions. The tree was drawn with Treeview 1. Page, and Figtree 1. Rambaut and Drummond, Presence of each of the eight retrotransposons was judged by presence of the amplified band using a FLK primer and a LTR primer, and in the case of full-length members, also by absence of the band using FLK primers at both sides of the retrotransposon.
According to the results, number of retrotransposons present in each accession was counted. To characterize the Mesoamerican ancestral genetic group of African and Asian accessions, we assumed that African and Asian Jatropha originated from different Mesoamerican genetic groups and then constructed scenarios. Number of inflorescences per plant, number of female flowers per plant, ratio of female to male flowers and seed yield g per plant of representative accessions from seven Mexican states [Chiapas 57 , Guerrero 4 , Michoacan 4 , Morelos 3 , Oaxaca 7 , Veracruz 20 , and Yucatan 5 ] were measured individually at the Rosario Izapa Experimental Farm, INIFAP Chiapas, Mexico.
Chiapas accessions were further sub-classified into those from six regions [Centro 14 , Frailesca 8 , Fronteriza 3 , Sierra 4 , Selva 2 , and Soconusco 26 ]. To compare the variation among accessions from central Chiapas Centro, Fronteriza, Frailesca, and Sierra , peripheral areas of Chiapas Selva and Soconusco , and other Mexican states, the mean value and standard deviation SD of each area were calculated. To survey the worldwide genetic variation of Jatropha, 59 effective SSR markers that showed the intraspecific polymorphism were selected from more than Jatropha SSRs.
The mean percentage of the missing data of SSR markers was 0. All of the eight RBIP markers showed the intraspecific polymorphism. The mean percentage of the missing data of RBIP markers was 1. There were no or low linkage between all the markers data not shown. The SSR markers yielded polymorphic bands ranging from two to seven with an average of 3. Among them, alleles were specific to Mesoamerica, whereas no allele was specific to Africa or Asia Supplementary Table 1.
The state of Chiapas had 47 specific alleles, which was the highest number among Mexican states and Guatemala. Remarkably, 39 Asian and African accessions were almost monomorphic and homozygote in both kinds of markers, except for five Vietnamese accessions, each of which was heterozygote in a single marker.
Genetic divergence of Jatropha in Mesoamerica. In Mesoamerica, the highest genetic variation was found in Chiapas, with a clear decreasing cline of H E from Chiapas and its bordering states to non-bordering states Figure 1B. These results showed that the highest genetic diversity of Jatropha exists in Chiapas. To further narrow down the center of genetic variation, H E was examined among the regions within Chiapas.
Slight differences between expected and observed heterozygosity H E versus H O were observed among the accessions from central Chiapas, whereas large differences between these statistics were detected among the accessions from the peripheral areas of Chiapas, other Mexican states, and Guatemala Figures 1B,C.
These resulted in lower inbreeding coefficients F IS in central Chiapas than in most of the peripheral areas of Chiapas, other Mexican states, and Guatemala Supplementary Table 1. Interestingly, in Soconusco, the southernmost peripheral region of Chiapas, F IS was the lowest, and in Sierra, one of the central regions, locating near to Soconusco, F IS was the second lowest. It is likely that effect of the human selection was little in these regions, but further research would be required to prove it.
The phenotypic variation of four yield-related traits was evaluated for Mexican accessions. The mean values and SDs of the accessions from central Chiapas were higher than those from the peripheral areas of Chiapas and other Mexican states Supplementary Table 4.
These suggest that Jatropha population in central Chiapas has the highest phenotypic variation in Mexico. The genetic constitutions of all the Mesoamerican accessions were examined by structure analysis. This indicates that the optical group number of all Mesoamerican accessions is 3, and then accessions from each region were classified into three clear genetic groups: A, B and C, by the model-based clustering analysis Figure 2. The numbers and ratios of accessions assigned to each group in each Chiapas region, other Mexican states and Guatemala are presented in Figure 3.
The distribution of the groups revealed a distinct geographic cline. Accessions from central Chiapas were mostly in Group A orange. Accessions in Group B purple were mainly distributed in the peripheral areas of Chiapas and in neighboring states and countries, whereas accessions in Group C blue were mainly distributed in states distant from Chiapas Guerrero, Michoacan, and Morelos. This geographical distribution of Jatropha genetic groups in Mesoamerica has not been reported before.
The distribution of Group B is especially interesting, because it seems to surround the area of Group A. Three genetic populations, Groups A, B and C, are indicated in orange, purple, and blue, respectively. Mesoamerican group of each accession is indicated with different group color. The origin of each accession is shown above see Supplementary Table 1 for origins. Eight accessions that classified into the African and Asian group Supplementary Figure 2.
Accessions carrying all the eight retrotransposons. Sizes of the circles correspond to the sample sizes. Mexican states were colored green. Central Chiapas is colored blue and peripheral areas of Chiapas is colored brown.
Production of cytotoxic compounds in dedifferentiated cells of Jatropha curcas L. (Euphorbiaceae).
Jatropha curcas L. Jatropha , a shrub species of the family Euphorbiaceae, has been recognized as a promising biofuel plant for reducing greenhouse gas emissions. However, recent attempts at commercial cultivation in Africa and Asia have failed because of low productivity. It is important to elucidate genetic diversity and relationship in worldwide Jatropha genetic resources for breeding of better commercial cultivars. Here, genetic diversity was analyzed by using accessions from Mesoamerica, Africa and Asia, based on 59 simple sequence repeat markers and eight retrotransposon-based insertion polymorphism markers. We found that central Chiapas of Mexico possesses the most diverse genetic resources, and the Chiapas Central Depression could be the center of origin.
Jatropha curcas L. Jatropha , a shrub species of the family Euphorbiaceae, has been recognized as a promising biofuel plant for reducing greenhouse gas emissions. However, recent attempts at commercial cultivation in Africa and Asia have failed because of low productivity. It is important to elucidate genetic diversity and relationship in worldwide Jatropha genetic resources for breeding of better commercial cultivars. Here, genetic diversity was analyzed by using accessions from Mesoamerica, Africa and Asia, based on 59 simple sequence repeat markers and eight retrotransposon-based insertion polymorphism markers.