Santos M R, Dias J S, Silva M J, Ferreira-Pinto M M
ECO-BIO, Instituto de Investigação Científica Tropical, Tapada da Ajuda, Apartado 3014, PT-1301-901 Lisboa, Portugal.
Commun Agric Appl Biol Sci. 2006;71(3 Pt B):963-71.
The biothrofic pathogen Albugo candida (Pers.) attacks all the cultivated Brassica species and several wild crucifers causing the disease known as white rust. The symptoms consist on the initial appearance of more or less conspicuous white sori on the plant leaves and stems, followed by severe distortions of the affected organs, especially flowers and siliqua. On delicate vegetable types of Brassica rapa L., like pak choi (B. rapa var. chinensis L.) and chinese cabbages (B. rapa var. pekinensis L.) even a slight white rust infection can render all the production unmarketable. Development of resistant cultivars is the best way to control the disease and to insure low pesticide spraying and residues in vegetables. The objective of this work were: i) the screening of a collection of B. rapa accessions from several seed banks for sources of resistance to white rust; and ii) the study of the inheritance of resistance in the most resistant accessions. Forty three accessions of B. rapa chinensis and 19 accessions of B. rapapekinensis were screened at the cotyledon stage following the methods of Santos and Dias (2004) with a Portuguese A. candida isolate Ac506 (Br) collected from turnip leaves. Four accessions of B. rapa chinensis presented more than 50% of resistant plants: the pak choi (BRA 117) was the most resistant accession with 85% of resistant plants, followed by pak choi (BRA227) with 73%, pai tsai 'Ex China 1' (B00083) with 60% and pak choi 'Ai Jiao Huang' (BRA 225) with 53%. On the opposite, B. rapa pekinensis accessions were all consider as susceptible presenting only 0-11% of resistant plants. The inheritance of resistance was studied in two crosses between pak choi BRA 117 and the rapid cycling B. rapa plant line CrGC 1.19. Selfed parents and F1 and F2 generations were produced, and screened at the cotyledon stage as previously described. Analysis of the results suggests that inheritance of resistance to Ac506 in pak choi BRA 117 is controlled by two nuclear genes with dominant recessive interaction.
生物营养病原菌白锈菌（Albugo candida (Pers.)）侵袭所有栽培的芸苔属物种以及几种野生十字花科植物，引发被称为白锈病的病害。症状表现为在植物叶片和茎上最初出现或多或少明显的白色病斑，随后受影响的器官，尤其是花朵和角果会严重变形。对于像小白菜（B. rapa var. chinensis L.）和大白菜（B. rapa var. pekinensis L.）这类娇嫩的芸苔属蔬菜品种，即使是轻微的白锈病感染也会使所有产量无法上市销售。培育抗病品种是控制该病害以及确保蔬菜中低农药喷洒量和残留量的最佳方法。这项工作的目标是：i）从几个种子库中筛选一批芜菁的种质资源，寻找对白锈病的抗性来源；ii）研究最抗病种质资源中抗性的遗传特性。按照Santos和Dias（2004年）的方法，在子叶期对43份小白菜种质和19份大白菜种质进行了筛选，使用从芜菁叶片上采集的葡萄牙白锈菌分离株Ac506 (Br)。4份小白菜种质表现出超过50%的抗病植株：小白菜（BRA 117）是最抗病的种质，抗病植株比例为85%，其次是小白菜（BRA227），抗病植株比例为73%，白菜‘Ex China 1’（B00083）抗病植株比例为60%，小白菜‘矮脚黄’（BRA 225）抗病植株比例为53%。相反，大白菜种质均被视为易感品种，抗病植株比例仅为0 - 11%。在小白菜BRA 117与快速循环的芜菁品系CrGC 1.19之间的两个杂交组合中研究了抗性的遗传特性。产生了自交亲本以及F1和F2代，并按照之前描述的方法在子叶期进行筛选。结果分析表明，小白菜BRA 117对Ac506的抗性遗传由两个具有显性 - 隐性相互作用的核基因控制。
