经济作物无性繁殖讲座(一) 无性繁殖的遗传稳定性和变异性

无性繁殖就 是不通过性细胞 而用植物的营养 器官进行的繁殖。很多植物其营养器官具有再生能力,例如扦插枝条能生根、插很能长枝、叶子能再生新根新茎;将一种植物和另一种植物嫁接起来形成新的植株,也是一种无性繁殖;分株、分根都是营养器宫的繁殖。一般来说,无性繁殖是自然界存在的一种特性,但是,通过人工的手段可以发挥和利用这种特性,作为一种繁殖的方法,形成生产上需要的无性系。

宜宾早茶有了本土新品种

四川早白尖茶业有限公司选育的茶树新品种“乌蒙早”正式通过了四川省农作物品种审定委员会审定，命名为“乌蒙早”。“乌蒙早”是产自高县罗场镇金塘村的一个原生品种，其母树当地俗称“大树茶”，相传有千年历史，经早白尖科研人员挖掘、开发，进行无性繁植，30年来已培育出200多亩茶园。“大树茶”属乔木型山茶科植物，其生物性状和经济性状均非常优秀，它发芽早、产量高、抗逆性强、

AGE STRUCTURES OF MODULES OF CLONAL PEATLAND SEDGE Carex middendorffii

Age structure of a plant population carries important information on population dynamics. The traditional age classification of individuals by development phases could not explain the generation relationship neither between individuals nor between modules, and it could not accurately predict the future of population or the tendency of peatland evolution. In a peatland of the Xiao Hinggan Mountains, China, at the middle of the growth season, the age structures of 3 modules, ramets, active buds and rhizomes of a Carex middendorffii clonal population were investigated, with the method of classifying age classes of ramets and active buds by counting generation quantity of tiller nodes, and classifying age classes of rhizomes by their real survival time. The quantity of vegetative ramets was dominant. Tiller nodes of ramets can propagate vegetatively for a maximum of 3 generations. The population of ramets consisted of 3 age classes of ramets at the middle of the growth season, and showed a stable age structure. In the two sampling events, there was no significant difference between quantities and age structure of the population. The maximum age of an excavated rhizome was 12 years old. Rhizomes were classified in 8 age classes, and age classes 4-6 contributed most to the total biomass. There was no significant difference in total length and total biomass per unit area, or in biomass per unit length in rhizomes between the two samplings. Four age classes of active buds were recognized, and their number increased from July to August. The Carex middendorffii clonal population achieved regeneration by budding from the tiller nodes of ramets. The age structures of the 3 modules suggested that the Carex middendorffii clonal population could persist in the early development phase of the oligotrophic peatland in the Xiao Hinggan Mountains, but it could not be dominant. It also faces the risk to disappear from the community as the peatland develops further.

Cloning and characterization of a FLORICAULA/LEAFY ortholog, PFL, in polygamous papaya

The homologous genes FLORICAULA (FLO) in Antirrhinum and LEAFY (LFY) in Arabidopsis are known to regu- late the initiation of flowering in these two distantly related plant species. These genes are necessary also for the expression of downstream genes that control floral organ identity. We used Arabidopsis LFY cDNA as a probe to clone and sequence a papaya ortholog of LFY, PFL. It encodes a protein that shares 61% identity with the Arabidopsis LFY gene and 71% identity with the LFY homologs of the two woody tree species: California sycamore (Platanus racemosa) and black cottonwood (Populus trichocarpa). Despite the high sequence similarity within two conserved regions, the N-terminal proline-rich motif in papaya PFL differs from other members in the family. This difference may not affect the gene function of papaya PFL, since an equally divergent but a functional LFY ortholog NEEDLY of Pinus radiata has been reported. Genomic and BAC Southern analyses indicated that there is only one copy of PFL in the papaya genome. In situ hybridization experiments demonstrated that PFL is expressed at a relatively low level in leaf primordia, but it is expressed at a high level in the floral meristem. Quantitative PCR analyses revealed that PFL was expressed in flower buds of all three sex types - male, female, and hermaphrodite with marginal difference between hermaphrodite and unisexual flowers. These data suggest that PFL may play a similar role as LFY in flower development and has limited effect on sex differentiation in papaya.

Plant Growth Regulators, Light and Temperature Influenced Micropropagation and Successful Field Establishment of Vernonia amygdalina Del.

Vernonia amygdalina Del. is a tropical species susceptible to frost which is an annual phenomenon of the winter season of the Eastern Cape. Limited populations of the species arc in the province dieback during the winter period, thereby making large scale cultivation through conventional vegetative propagation impossible. In our effort to increasing the population of the species within the province, a micropropagation approach through tissue culture teehnology was employed. Two growth regulators （BAP ＆ NAA） were tested at four levels of concentration under continuous light and dark conditions. Plantlets were subsequently transferred to the field after acclimatization at different temperature conditions. The result of the study showed that BAP generally performs better than NAA for callus induction under continuous darkness, while direct micropropagation of shoot under continuous light condition at I mg L^-1BAP showed the best result. To achieve greater success for the rapid multiplication of the species, this study further demonstrates that the optimum temperature range for acclimatizing the species prior to the transfer of the plantlet to the field is between 23 ±3 ℃.