PATTERNS OF KARYOTYPE DIFFERENTIATION OF SOME GEOGRAPHICAL RACES OF CUNNINGHAMIA LANCEOLATA

Cunninghamia lanceolata (Lamb.) Hook., one of the most important timber trees of China, is nowadays extensively cultivated in the subtropical regi on of this country. Materials collected from populations of five artificial orests of different geographical locations, namely, Jinzhai of Anhui Province, Huitong of Hunan Province, Rongshui of Guangxi Zhuang Autonomous Region, Jianou of Fujian Province, and Xinyi of Guangdong Province, have been investigated karyologically (karyotype analyses and DNA contents).The karyotypes of Cunninghamia lanceolata of samples of the above mentioned localities exhibit a minor yet notable difference, and could therefore be divided into two types: (1) Type A: K(2n)=22=L₆^m+S₁₄^m+S₂^m, and(2) Type B: K(2n)=22=L₈^m+S₁₄^m. Both of these types possess a pair of satellite chromosomes, though the positions of the satellites are various. The occurrence of B-chromosomes is relatively rare, only confined to the races of the two inland localities—Huitong and Rongshui. It is worthy of note that the ratios of the two types of karyotype vary in the samples we examined, i. e., the lower the latitude of the location of geographical races, the higher the frequency of occurrence of Type A (Table 3).The relative DNA contents (Table 5) of Jinzhai, Huitong and Xinyi plants increase with ascending latitudes and display more or less a clinal variation pattern. The nature of this phenomenon, which is probably directly adaptive to temperature and other environmental conditions, is discussed.