Development and characterization of Brassica juncea fruticulosa introgression lines exhibiting resistance to mustard aphid

摘要

Background: Mustard aphid is a major pest of Brassica oilseeds. No source foraphid resistance is presently available in Brassica juncea . A wild crucifer,Brassica fruticulosa is known to be resistant to mustard aphid. An artificiallysynthesized amphiploid, AD-4 (B. fruticulosa x B. rapa var. brown sarson) wasdeveloped for use as a bridge species to transfer fruticulosa resistance to B.juncea. Using the selfed backcross we could select a large number of lines withresistance to mustard aphid. This paper reports cytogenetic stability ofintrogression lines, molecular evidence for alien introgression and theirreaction to mustard aphid infestation. Results: Majority of introgression lineshad expected euploid chromosome number(2n= 36), showed normal meiosis and highpollen grain fertility. Well-distributed and transferable simple-sequencerepeats (SSR) markers for all the 18 B. juncea chromosomes helped tocharacterize introgression events. Average proportions of recipient and donorgenome in the substitution lines were 49.72 and 35.06%, respectively. Minimumalien parent genome presence (27.29%) was observed in the introgression line,Ad3K-280 . Introgressed genotypes also varied for their resistance responses tomustard aphid infestations under artificial release conditions for twocontinuous seasons. Some of the test genotypes showed consistent resistantreaction. Conclusions: B.juncea-fruticulosa introgression set may prove to be avery powerful breeding tool for aphid resistance related QTL/gene discovery andfine mapping of the desired genes/QTLs to facilitate marker assisted transferof identified gene(s) for mustard aphid resistance in the background ofcommercial mustard genotypes.