Wild Buckwheat Species in the San Jiang (Three Rivers) Area of Southwestern China

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1 Proceedings ofthe 9th International Symposium on Buckwheat, Prague 2004 Wild Buckwheat Species in the San Jiang (Three Rivers) Area of Southwestern China Ohmi Ohnishi Plant Germ Plasm Institute, Graduate School ofagriculture, Kyoto University Nakajo 1, Mozume-cho, Mukoh Japan ABSTRACT The Three Rivers Area of southwestern China is considered to be the original birthplace of both common and Tartary buckwheat. The search for wild buckwheat species in this area was accomplished by conducting 5 expeditions to this area since Both wild common buckwheat and wild Tartary buckwheat were found to be abundant in this area. In the northernmost area (upper stream area), wild Tartary buckwheat was the only wild Fagopyrum species found. A new species F. jinshaense was found, but only in the valleys of the Jinshajiang and its tributaries, whereas the wild species F. gilesii was found only in the valley of Lanzangjiang itself. The high mountains (Mts. Hengduan) in this area have been a critical barrier for the diffusion offagopyrum species. Two wild species, F cymosum and F gracilipes, appear to have overcome this barrier and have diffused further west to the Himalayan region. Keywords: Fagopyrum gilesii, Fagopyrum jinshaense, San Jiang Area, wild buckwheat, wild Tartary buckwheat INTRODUCTION Three large rivers, the Jinshajiang, Lancanjiang and Nujiang, run parallel to each other and roughly from north to south through the area bordering Yunnan, Sichuan and eastern Tibet. This area is referred to as the San Jiang Area (the Three Rivers Area). This area was probably the original birthplace of both common and Tartary buckwheat. Allozyme analysis ofwild Tartary buckwheat CORNISHI, 2000, 2002), and RAPD and AFLP analyses ofwild and cultivated Tartary buckwheat (TSUJI AND OHNISHI, 2000, 200Ia,b) confirmed that the genotype of wild Tartary buckwheat, having the same genotype as cultivated Tartary buckwheat, first arose in this area. Allozyme and AFLP analyses of natural populations of both wild common buckwheat and cultivated common buckwheat suggested that the natural populations from the Three Rivers Area are the most closely related to present cultivated populations ofcommon buckwheat CORNISHI AND KONISHI, in preparation). Therefore, this area was considered as being extremely important in the search for natural populations of wild ancestors of both common and Tartary buckwheat. However, this region was not originally considered to be the centre of species diversity of Fagopyrum as revealed by OHNISHI (1995). We initiated a project to search for wild buckwheat species in the Three Rivers Area in So far we have visited this area five times and now have surveyed the species, which are growing in this area. A portion ofthe results from these expeditions has already been published (TSUJI ET AL. 1999, OHNISHI AND KONISHI, 2001, OHNISHI, 2002). This report is a summary ofthe five expeditions to the Three Rivers Area. Travelling routes of five expeditions The five expeditions covered almost all the regions bordering the main roads connecting Yunnan and Sichuan to Tibet. These are shown in detail in Fig. 1. Some indications of the geography of the Three Rivers Area are shown in Fig. 2. The three large rivers flow through deep valleys that run almost straight north to south. A major road runs along the Lancanjiang, but no road is available along the Jinshajiang River. Villages are situated on the riverbanks of the main rivers and along the tributary valleys that have sufficient agricultural land, and in some cases on mountain slopes with land that is suitable for cultivation and which are located far above the major riverbeds (Fig. 2). Rice was found to be 226

2 Proceedings o/the 9 h InteT7Ullional Symposium on BuckwheaJ, Prague 2004 the major crop produced by the farmers in the lower wanner areas, wh.ereas maze produc~ion took the place of rice in the higher or cooler areas. Buckwheat and millets are found mal~ly on the mountain slopes (see Fig. 2). The production of common buckwheat was popular (FIg. 2) in this area, but Tartary buckwheat was also found to be cultivated to a lesser extent. In the higher agricultural areas, above 3000m asl, the cultivation ofbarley was dominate. Characteristics ofwild F. tataricum populations Studies on the origin of cultivated Tartary buckwheat were conducted by analysing cultivated and wild Tartary buckwheat populations from different areas using molecular markers, such as RAPD and AFLP (Tsun AND OHNISHl, 2001, 2003) and by utilizing allozyrnes (OHNISHl, 2000, 2002). All ofthese studies suggested that natural populations from central Tibet, the Himalayan hills and northern Pakistan are related the closest to cultivated Tartary buckwheat. However, these studies also demonstrated that the same or closely related genotypes, to those of cultivated Tartary buckwheat, are found in the Three Rivers Area. As the agricultural activity was very poor in ancient times as well as during the present time, in these central Tibetan and high Himalayan mountain regions, it was considered that these regions could not be the original birthplace oftartary buckwheat (TSUJI AND OHNISHI, 2001a, b). Tsun AND OHNISHl (2001a, b) concluded that a search for and genetic analysis of the natural populations of wild Tartary buckwheat in the Three Rivers Area was necessary for a more complete understanding ofthe origin of cultivated Tartary buckwheat. Wild Tartary buckwheat grows in the Deqin and Zhongdian districts of Yunnan province, in the Degu, Batang, Derong districts of Sichuan province and in the Markang, Zuogong, Basu, Chaya, Jiangda and Changdu districts of eastern Tibet in the Three Rivers Area. Along the northern Chuanzhou (Sichuan-Tibet) road connecting Chendu and Lhasa, wild Tartary buckwheat was the only wild Fagopyrum species found to be growing there. It was found growing along the roadsides and in the margins of cultivated fields. We analysed the newly sampled natural populations of both wild and cultivated Tartary buckwheat with respect to allozymes with the results conf1l1lling our original conclusion on the origin of cultivated Tartary buckwheat (OHNISHI in preparation). Distribution of F. esculentum ssp. ancestrale Since OHNISHI (1991) first discovered the wild ancestor of common buckwheat growing in the Yongsheng district of Yunnan province, natural populations of this wild ancestor have also been found in the Muli and Yanyuan districts of Sichuan province and in the Lijiang and Deqin districts ofyunnan province. During the last five years, many more natural populations were found in the Three Rivers Area, mainly in the Markang district ofeastern Tibet (see Fig. 3). Phylogenetic analysis ofthese natural populations and ofthe cultivated populations of common buckwheat in this region, utilizing AFLP markers (KONISHI YASUI AND OHNlSHI in preparation), revealed that the natural populations from the Three Rivers Area are the most closely related to cultivated common buckwheat. This implies that the Three Rivers Area was the original birthplace of cultivated common buckwheat. The same conclusion was achieved by allozyrne analyses ofboth wild and cultivated common buckwheat (OHNISHI unpublished). However, there remains the possibility of gene flow from cultivated common buckwheat to wild common buckwheat or vice versa, which may in turn lead to an erroneous conclusion. We are now attempting to analyse gene flow between wild and cultivated common buckwheat through the use ofmicrosatellite markers. 227

3 Proceedings ofthe 9th International Symposium on Buckwheat, Prague 2004 Distribution of R jinshaense and R gilesii F jinshaense Ohsako et Ohnishi was recently registered as a new species (OHSAKO AND OHNISHI 2002). This species was found to be morphologically similar to F gilesii and F. leptopodum. However, it was shown by molecular phylogenetic analysis that F jinshaense was related to F. gilessi and F. leptopodum in nuclear DNA, but was related to F urophyllum in their chloroplast DNA (NISHIMOTO ET AL. 2003, OHNISHI AND KAWASAKI unpublished). The most remarkable finding with the species F. jinshaense was the sharp geographical differentiation between F. jinshaense and F. gilesii. Fagopyrum jinshaense was found to be distributed only in the Jinshajiang and its tributary valleys, whereas F. gilesii was distributed only in the Lancanjiang valley (Fig. 3). OHNISHI AND KAWASAKI (unpublished) observed upper-lower stream differentiation of chloroplast DNA variations which were found in F. gilesii along the Lancangjiang river. Any similar differentiation was not found in F jinshaense. Distribution of diploid R homotropicum Fagopyrum homotropicum which was found to be distributed in the Three Rivers Area was expected to be tetraploid, judging from the result of OHNISHI AND ASANO (1999). In fact, most of the accessions that were collected in the Three Rivers Area were found to be tetraploid. However, there was a unique sample of F. homotropicum from the village of Changbo in the Batang district of Sichuan province. The F homotropicum population found growing in this village was a mixture of both diploid and tetraploid plants. Among diploid plants there existed plants with nonnal morphology as well as plants with red leaves and red pericarps with enlarged flanges (Fig. 4). These exceptional plants were revealed to be diploid and are quite distinct in allozyme genotypes from those with normal morphology. Studies on the origin or differentiation processes ofthis Changbo population are now in progress. Wide spread of R cymosum and R grqcilipes Two additional wild species were found to be growing in the Three Rivers Area; these being F. gracilipes and F. cymosum. F. gracilipes was commonly found growing in agricultural fields. This species is known to have spread as far as western Bhutan. Local differentiation of this species has not yet been studied in detail. The high mountains (Mts. Hengduan) in the Three Rivers Area appear to have been a critical barrier for the distribution of Fagopyrum species. Only two species, F. gracilipes and F. cymosum, appear to have overcome this barrier. For further details on the difusion and differentiation off. cymosum in southen China and in the Himalyan region, including the Three Rivers Area, please refer to YAMANE ET AL. (2003). 228

4 "J..J v~. Proceedings ofjlre!f'h hr/ema/ional Symposium on Buckwheal, Prague 1004 Fig. I Travelling routes in the Three Rivers Area of southwestern China Fig. 3 Distribution ofwild Fagopyrum species in the Three River Area. 229

5 Proceeding.f of{he 9'h Intern-lliiona! Symposiwn on Buckwheat. Prague 2004 Fig. 2 Pictures showing the geography of the Three Rivers Area. A. The Lanzangjian and cultivated fields on the riverbank. B. Cultivation ofcommon buckwheat at upper Yanjing ofmarkan district ofeastern Tibet. C. Barley fields along the tributary ofthe Nujiang. D. A camping site ofnomadic peoples for Yak. breeding near Bamda, Basu district ofeastern Tibet. Only wild Tartary buckwheat can be found in this kind of sites. 230

6 Proceedings of IIu? 9" Jntemal;unal S.vmposiwn on Buc/.:wheal. Prague 2004 Fig. 4 F. homolropicum plants that have red leaves and red pencarp with enlarged flanges found in Changbo village of Batang district, Sichuan province. ACKNQWLEDGM ENTS I am grateful to Dr. Clayton Campbell, Karle Research Ltd., Manitoba, Canada for reading the manuscript, correcting the English and giving several useful suggestions. REFERENCES NISHIMOTO, Y., O. OHNISHI AND M. HASEGAWA (2003): Topological incongruence between nuclear and chloroplast DNA trees suggesting hybridization in the urophyljum goup of the genus Fagopyrum (Polygonaceae) Genes & Genet. Syst. 78: OHNrSHI, O. (1991); Discovery ofthe wild ancestor ofcommon buckwheat. Fagopyrum II:

7 Proceedings ofthe f)h Imernational Symposium on Buckwheat, Prague 2004 OHNISHI, O. (1995): Discovery of new Fagopyrum species and its implication for the study of evolution of Fagopyrum and of the origin of cultivated buckwheat. Proc. 6 th Intl. Symp. Buckwheat at Ina: OHNISHJ, O. (2000): Geographical distribution of auozymes in natural populations of wild Tartary buckwheat. Fagopyrurn 17: OHNJSHI, O. (2002):. Wild buckwheat species in the border area of Sichuan, Yunnan and Tibet and allozyrne diversity ofwild Tartary buckwheat in this area. Fagopyrum 19: 3-9. OHNISH1, O. AND N. ASANO (1999):. Genetic diversity of Fagopyrum homotropicum, a wild species related to common buckwheat. Genet. Res. Crop Evo!. 46: OHNISHI, O. AND T. KONISHI (2001): Cultivated and wild buckwheat species in eastern Tibet. Fagopyrum 18: 3-8. OHSAKO, T., K. YAMANE AND O. OHNISHI (2002): Two new Fagopyrum (Polygonaceae) species, F. gracilipedoides and F. jinshaense from Yunnan, China. Genes & Genet. Syst. 77: TSUJI, K. AND O. OHNISHJ (2000): Origin of cultivated Tartary buckwheat (Fagopyrum tataricum Gaert.) revealed by RAPD analyses. Genet. Res. Crop Evo!. 47: TSUJI, K. AND O. OHNISHf (2001 a): Phylogenetic position of east Tibetan natural poulations in Tartary buckwheat (Fagopyrum tataricum Gaert.) revealed by RAPD analyses. Genet. Res. Crop Evo!. 48: TSUJI, K. AND O. OHNISHI (200lb): Phylogenetic relationships among wild and cultivated Tartary buckwheat (Fagopyrum tataricum Gaert.) populations revealed by AFLP analyses. Genes & Genet. Syst. 76: TSUJI, K., Y. YASUI AND O. OHNJSHJ (1999): Search for Fagopyrum species in eastern Tibet. Fagopyrum 16: