Identification of molecular markers associated with resistance to squash silverleaf disorder in summer squash (Cucurbita pepo)

Abstract

Squash silverleaf (SSL), caused by the silverleaf whitefly [Bemisia argentifolii (formerly known as Bemisia tabaci Gennadius, B strain)], is an important physiological disorder that affects squash (Cucurbita spp.) by reducing yield potential. Breeding squash with resistance to SSL disorder can be facilitated by using marker-assisted selection (MAS). Resistance to SSL disorder, in Cucurbita pepo, is conferred by a single recessive gene (sl). The objective of this study was to identify molecular markers associated with resistance. A zucchini squash, SSL disorder resistant breeding line, 'Zuc76' (sl/sl) and a SSL disorder susceptible zucchini cultivar 'Black Beauty' (Sl/Sl) were screened with 1,152 randomly amplified polymorphic DNA (RAPD) primers and 432 simple sequence repeat (SSR) markers to identify polymorphisms. Using F 2 and BC 1 progeny segregating for SSL disorder resistance, three RAPD (OPC07, OPL07 and OPBC16) primers and one SSR (M121) marker were found associated with sl. Fragments amplified by RAPD primer OPC07 was linked in coupling phase to sl, whereas RAPD primer OPL07 was linked in repulsion phase. RAPD primer OPBC16 and SSR marker M121 were co-dominant. The allelic order of these loci was found to be M121-sl-OPC07-OPL07-OPBC16. The closest marker to sl is M121 with an estimated genetic distance of 3.3 cM. The markers identified in this study will be useful for breeding summer squash (C. pepo) for SSL disorder resistance derived from zucchini squash breeding line 'Zuc76'.

A high-density linkage map and QTL mapping of fruit-related traits in pumpkin (Cucurbita moschata Duch.)

“…The developed SNP markers linked to fruit-related traits in the loci facilitates molecular breeding of new varieties through marker-assisted selection (MAS). It has been proved effective for improving quantitative and qualitative traits in cucumber 53 – 56 , melon 57 , 58 , watermelon 59 , 60 even Cucurbita species, C. pepo 61 . However, it was still in its infancy for application in C. moschata .…”

Efficiency of RAPD in assessing genetic variation in commercially viable local varieties of blueberry (<i>Vaccinium</i>)

“…However, these morphological characteristics are late in their expression, making it impossible to recognize the clones in the early stage of their development. A more efficient tool to be able to recognize different clones is the use of molecular markers [6,11], examples of which are those based on isoenzymes and DNA. Of the techniques based on DNA, the most notable are AFLP (amplified fragment length polymorphism) [12,13] RFLP (restriction fragment length polymorphism), SSRs (simple sequence repeats) [14], microsatellites and RAPD (randomly amplified polymorphic DNA) [13,15].…”