THE STUDIES OF THE PLANT COLD－RESISTER AND ITS APPLICATION IN RECE SEEDLING RAISING

ＴＨＥＳＴＵＤＩＥＳＯＦＴＨＥＰＬＡＮＴＣＯＬＤ－ＲＥＳＩＳＴＥＲＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＩＮＲＥＣＥＳＥＥＤＬＩＮＧＲＡＩＳＩＮＧＪｉａｎＬｉｎｇ－ｃｈｅｎｇ;ＳｕｎＬｏｎｇ一ｈｕａ;ａｎｄＷｅｉＸｉａｎｇ－ｙｕｎ（ｉｎｓｔｉｔｕｔｅｏｆ...     

THE POTENTIAL FOR PALAEOBOTANY IN THE EXPLANATION OF CHINA''''S PLANT GEOGRAPHY

The distributions of many plant taxa in China at the present day indicate centres of floristic importance which may be ancient,and have evolutionary significance,or which may be only their latest locations in a Cenozoic history of migrations.This paper summarizes the present and Cenozoic distributions in China of the following taxa:Nitraria,Ephedra,Carya,Liquidamber,Pterocarya,Betulaceae.It is concluded that the centres of importance of the named genera are different now from what they were at some time in the Cenozoic past;each has accomplished major migrations and suffered significant extinctions during that period.The history of the Betulaceae is less clear but in principle soluble.     

THE HIMALAYA AS A CENTRE OF CONCENTRATION FOR THE SOUTH-EASTERN ASIATIC POLYPODIACEOUS FERNS

Before summing up the essential points brought forward in the present paper,it seems desirable at the outset to circumscribe briefly the geographical boundary of the Himalaya.We all know that the Himalaya is an extraordinarily gigantic upheaval of the landmass in the world,yet,up to the present,geologists and geographers are still divided in the concept of its geographical boundary.It has so far unequivocally been recognized that the mountain range west of the great bend of the famous Tsangpo Gorge in southeastern Tibet running     

DO RECENT FINDINGS IN PLANT MITOCHONDRIAL MOLECULAR AND POPULATION GENETICS HAVE IMPLICATIONS FOR THE STUDY OF GYNODIOECY AND CYTONUCLEAR CONFLICT?

The coexistence of females and hermaphrodites in plant populations, or gynodioecy, is a puzzle recognized by Darwin. Correns identified cytoplasmic inheritance of one component of sex expression, now known as cytoplasmic male sterility (CMS). Lewis established cytonuclear inheritance of gynodioecy as an example of genetic conflict. Although biologists have since developed an understanding of the mechanisms allowing the joint maintenance of CMS and nuclear male fertility restorer genes, puzzles remain concerning the inheritance of sex expression and mechanisms governing the origination of CMS. Much of the theory of gynodioecy rests on the assumption of maternal inheritance of the mitochondrial genome. Here we review recent studies of the genetics of plant mitochondria, and their implications for the evolution and transmission of CMS. New studies of intragenomic recombination provide a plausible origin for the chimeric ORFs that characterize CMS. Moreover, evidence suggests that nonmaternal inheritance of mitochondria may be more common than once believed. These findings may have consequences for the maintenance of cytonuclear polymorphism, mitochondrial recombination, generation of gynomonoecious phenotypes, and interpretation of experimental crosses. Finally we point out that CMS can alter the nature of the cytonuclear conflict that may have originally selected for uniparental inheritance.