COMPARATIVE ANALYSES OF RFLP DIVERSITY IN LANDRACES OF TRITICUM-AESTIVUM AND COLLECTIONS OF T-TAUSCHII FROM CHINA AND SOUTHWEST ASIA

Chinese accessions of Triticum tauschii and T. aestivum L. from the Si chuan white (SW), Yunnan hulled (YH), Tibetan weedrace (TW), and Xinji ang rice (XR) wheat groups were subjected to RFLP analysis. T. tauschi i and landraces of T. aestivum from countries in Southwest Asia were a lso evaluated. For T. tauschii, a west to east gradient was apparent w here the Chinese accessions exhibited less diversity than those from S outhwest Asia. Compared to the Southwest Asian gene pool, the Chinese T. tauschii was highly homogeneous giving a low frequency of polymorph ic bands (16%) and banding patterns (1.33 per probe) with 75 RFLP prob e-HindIII combinations. Accessions of T. tauschii from Afghanistan and Pakistan were genetically more similar to the Chinese T. tauschii tha n those from Iran. Of 368 bands found for 39 Chinese hexaploid wheat a ccessions with 63 RFLP probe-HindIII combinations, 28.3% were polymorp hic with an average of 2.6 banding patterns per probe and 5.0 bands pe r genotype. The individual Chinese landrace wheat groups revealed less variation than those from Afghanistan, Iran, and Turkey. When classif ied into country based groups, however, the diversity level over all C hinese landraces was greater than that of some Southwest Asian landrac es, especially those from Afghanistan and Iran. The XR wheat group was genetically distinct from the other three Chinese landrace groups and was more related to the Southwest Asian landraces. The TW group was g enetically similar to, but more diverse than, the SW and YI-I groups. The Chinese landraces had a higher degree of genetic relatedness to th e Southwest Asian T. tauschii, particularly to accessions from Iran, r ather than to the Chinese T. tauschii. 'Chinese Spring' was most relat ed to 'Chengdu-guang-tou', a cultivar from the SW wheat group.