Isozyme variation in Helianthus petiolaris and sunflower,H. annuus

Summary Helianthus petiolaris is a wild species used in genetic improvement of sunflower, as a donor of cytoplasmic male sterility and of genetic resistance to diseases. Isozyme variation for ADH, ACP, EST, GDH, LAP, PGI, PGD and SKDH in this species was studied using starch gel electrophoresis. The patterns thus obtained were compared with zymograms of inbred lines, hybrids and open pollinated varieties of H. annuus. The same alleles for EST and SKDH isozymes were found in both species, while ACP showed an allele that has not been found in sunflower. The rest of the isozyme systems showed both common alleles and characteristic ones for each species. ACP, GDH and PGD were monomorphic in H. petiolaris, while ADH and LAP were monomorphic in H. annuus. The isozyme markers obtained here could be useful in breeding programs involving interspecific crosses, and studies on introgression and on genetic variation in other populations of this wild species.     

Plant Regeneration Through Anther Culture of Three Wild Species of Hordeum (H. murinum, H. marinum and H. bulbosum)

Plant regeneration was achieved through anther culture of three wild species of Hordeum (H. murinum, H. marinum and H, bulbosum). Calli or embryoids were formed from microspores in anthers cultured on a medium containing 6-benzylammopurine (BAP) and ficoll. These calli or embryoids regenerated green or albino shoots and roots after transfer to regeneration media. Green plantlets which developed on regeneration media were transferred to soil where they showed further growth.     

中国主要粮食作物野生种质资源地理分布

根据至1996年底国家种质资源数据库保存的资料讨论中国主要粮食作物野生种质资源的地理分布特点以及野生稻、半野生大麦和野生大豆种质资源地理分布及其区域分布。阐述了地理分布原因。讨论了保护作物野生种的迫切性。     

The Giemsa C-Banded Karyotype of Canada Wildrye (Elymus canadensis)

Karyotype of Canada wildrye (Elymus canadenisis L.) was described using giemsa C-banding techniques. Most of the chromosomes showed dome banding pattern polymorphism. Small to large terminal and centormere bands were observed in most of the chromosomes. A faint satellite was observed in one chromosome. Tow chromosomes had a large interstitial band near the centromeres in the long arms. The Giemsa C-banding pattern of E. Canadensis is compared to that of Pseudoroegneria spicata and Critesion boddanii to illustrate species relationship.     

Species affinities between Cajanus cajan and some Atylosia species based on esterase isoenzymes

Summary Esterase isozymes were studied in seed extracts of Cajanus cajan and six Atylosia species by polyacrylamide gel electrophoresis and isoelectrofocusing. The isozyme patterns were stable and accession specific. Within the accessions of the Atylosia species, A. albicans and A. scarabaeoides showed three common bands indicating that they are more closely related to each other than to the other species. Of the accessions of Atylosia only A. cajanifolia shares the esterase isozyme of C. cajan and hence seems to be the closest wild relative of C. cajan.     

Effects of gamma irradiation on in vitro pollen germination of different Cucumis species

Summary Pollen grains of 14 Cucumis accessions were irradiated with 0, 1, 2, 3 or 4 kGy acute gamma rays and germinated in vitro directly afterwards. Pollen germination was significantly reduced by increasing irradiation dose for all species, except C. melo var. agrestis. Pollen tube growth was generally reduced likewise. Pollen of two C. anguria subspecies was most sensitive to irradiation. Sensitivity of the pollen with respect to pollen tube growth in relation to irradiation dose was inversely related to total DNA amount per nucleus. In vitro germination was not related to DNA amount per nucleus. Results show that the examined Cucumis species, especially C. melo var. agrestis, are sufficiently resistant to irradiation to be used as donor species for in vivo egg cell transformation of the cucumber.     

Commercialization decisions and the economics of introduction

Summary A commercial horticultural industry that establishes plant-breeding nurseries for an exotic species throughout a regional economy will expand until the marginal profit of the last nursery established is zero. However, a regional government concerned with social welfare will take into account not only the profits of the horticultural industry but also any expected costs of an accidental invasion. The latter costs will consist of the discounted expected social damages due to an increase in the rate of invasion over time and the increase in expected damage cost per hectare caused by an additional nursery. A government can employ an “introducers' pay” tax equal to the latter social costs to ensure that the plant breeding industry establishes the optimal number of nurseries. We illustrate this outcome with the example of purple loosestrife (Lythrum salicaria) in North America. In the absence of any tax, the horticultural industry will establish n = 3528 nursery operations, and the expected damages from invasion are US$ 28.2 million per year. With the tax, only n = 300 nurseries are established but the expected damages from invasion are reduced to US$ 1.3 million per year. Although profits for the horticultural industry are lower from the tax, the net gains in overall social welfare more than offset the losses. Although these results are illustrative only, they show that the problem of plant invasives initiated by commercial operations is amenable to standard economic analysis and solutions, such as implementation of an “introducers' pay tax”.     

内蒙古巴盟小麦根病种类、数量及分布

1997～ 1999年 ,通过巴盟 5个旗 (县 )、2 0个乡、社的调查和 160 1份采集标样的室内病原菌分离、鉴定 ,结果表明 :巴盟地区小麦根病的主要病原菌为全蚀病菌 ,其分离频率最高为59 4 % ;次要病原菌有黄色镰刀菌 ,禾谷镰刀菌 ,麦根腐德氏霉 ,丝核菌 ,交链孢菌等 7种病原菌。全蚀病在 5个旗 (县 )均有不同程度的分布、发生数量约占根病的 80 %～ 90 %。     

Evaluation of resistance to sharka (Plum pox virus) of several Prunus rootstocks

Sharka (Plum pox virus, PPV) severely affects the production of most Prunus species in the areas affected by the disease. In this study, the resistance of 15 Prunus rootstocks to a Dideron type isolate of PPV was evaluated under controlled conditions in an insect‐proof greenhouse. After four cycles of study,‘GF677’ almond x peach hybrid,‘Myrobolan 29C plum and ‘L2’ cherry did not show any symptoms and were ELISA‐DASI and RT‐PCR negative. These were considered resistant to PPV. The rest of the rootstocks assayed showed symptoms of sharka (confirmed by ELISA‐DASI or RT‐PCR), although the level of susceptibility was different for each rootstock.‘GF305’ peach, ‘Puebla de Soto’ plum and ‘Real Fino’ apricot, were highly susceptible to PPV, showing strong sharka symptoms and being ELISA and RT‐PCR positive. ‘Marianna 2624’ plum,‘AC 9921‐07’ hybrid and ‘CP‐2’ plum showed susceptibility to PPV confirmed by ELISA‐DASI and RT‐PCR positives.‘Nemaguard’ and ‘Nemared’ hybrids, ‘Torinel’ plum and ‘STN2’ hybrid showed an intermediate susceptibility to PPV with slight sharka symptoms and were ELISA‐DASI and RT‐PCR positive. Whereas, ‘Montclar’ peach and ‘Evrica’ hybrid showed moderate resistance to PPV with slight sharka symptoms and were ELISA positive but RT‐PCR negative. The results open new possibilities in the search for different sources of resistance to PPV within Prunus.     

Development of B-Genome Chromosome Addition Lines of B. napus Using Different Interspecific Brassica Hybrids

By interspecific hybridization within the genus Brassica, trigenomic haploids were produced and back-crossed four times with B. napus, variety ‘Andor’. From this material, monosomic B-genome chromosome addition lines were selected with the extra chromosome derived from three different B-genome sources, i.e., B. nigra (BB), B. carinata (BBCC), and B. juncea (AABB). After selfing and/or microspore culture, disomic addition lines were obtained. Meiotic behavior was studied of the trigenomic hybrids, the pentaploid BC₁ plants, and the monosomic addition lines. The addition lines were shown to possess cytological stability and good fertility.