Genetic diversity and biochemical analysis of Capsicum annuum (Bell pepper) in response to root and basal rot disease, Phytophthora capsici.

This study analyzed the genetic variability and biochemical characteristics of edible and ornamental accessions of pepper, Capsicum annuum, in response to root and basal rot disease (RCR), caused by Phytophthora capsici, using resistance screening and genetic variability via Inter Simple Sequence Repeat marker (ISSR), bio-mass parameters, and enzymatic activity of Peroxidase or peroxide reductases (POX), Superoxide dismutase (SOD), Polyphenol oxidase (PPOs), Catalase (CAT), Phenylalanine ammonia-lyase (PAL), ß-1,3-glucanase and phenolic content. The resistance in C. annuum '37ChilPPaleo', '19OrnP-PBI' and '23CherryPOrsh' and susceptibility in '2BP-PBI', '24BP-301' and '26BPRStarlet' accessions were confirmed. Nineteen out of 21 ISSR primers generated 185 polymorphic bands with a mean percentage band of 98.5 %, and an average number of bands of 9.9 per primer. Biomass parameters were significantly higher in resistant genotypes than the susceptible ones and non-inoculated controls. All the seven candidate enzymes were highly up-regulated in the resistant C. annuum accessions '19OrnP-PBI', '37ChillP-Paleo' and '23CherryP-Orsh' inoculated with P. capsici The mean level of enzyme activity varied from 1.5 to 5.6-fold higher in the resistant C. annuum, of which SOD was increased by 5.6 fold, followed by PAL 4.40 and PPO 3.75 fold in comparison to susceptible and non-inoculated controls. Overall, there was no significant correlation between resistance and genetic variability, and also between genetic variability and enzyme activity levels. However, there was a highly significant correlation between the resistance, bio-mass parameters and enzyme activity levels.

Analysis of candidate genes expression associated with defense responses to root and collar rot disease caused by Phytophthora capsici in peppers Capsicum annuum.

Root and collar rot disease caused by Phytophthora capsici (Leonian) is one of the most serious diseases in pepper, Capsicum annuum L. Knowledge about resistant genes is limited in pepper accessions to P. capsici. In this study, a diverse collection of 37 commercial edible and ornamental genotypes, and implication of seven novel candidate DEGs genes (XLOC_ 021757, XLOC_021821, XLOC_012788, XLOC_011295, XLOC_021928, XLOC_015473 and XLOC_000341) were up-regulated on resistant and susceptible pepper cultivars, through real-time polymerase chain reaction (qPCR) at transplanting and maturing stages. All seven related defense-gene candidates were up-regulated in all inoculated accessions to P. capsici, but these genes were highly expressed in resistant ones, 19OrnP-PBI, 37ChillP-Paleo, and 23CherryP-Orsh. The transcriptional levels of the seven related candidate DEGs were 5.90, 5.64, 5.62, 5.18, 3.94, 3.69, 3.16 folds higher in the resistant pepper genotypes, than the control ones, non-inoculated genotypes respectively. The candidate genes expressed herein, will provide a basis for further gene cloning and functional verification studies, and also will aid in an understanding of the regulatory mechanism of pepper resistance to P. capsici.

Cefotaxime and Benzyladenine Improve Melon Regeneration.

BACKGROUND: Worldwidely cultivated, melon is commercially an important fruit crop, as it is in Iran. OBJECTIVES: Establishment of an efficient in vitro plant regeneration system plays a pivotal role in the plant transformation, hence, the importance of regeneration protocol for Iranian melon (Cucumis melo L. var. Gorgab) has encouraged us to work on in vitro melon regeneration. MATERIAL AND METHODS: The effect of selective media, including various concentrations of the 6-benzyladenine (BA), cefotaxime, as well as indole-3-acetic acid (IAA) on regeneration of the cotyledonary petioles derived from a 6-day-old in vitro grown seedlings were assessed. RESULTS: The highest frequency of regeneration rate was recorded at 1.5 mg.L-1 of the BA plus 250 mg.L-1 cefotaxime in addition to 1 mg.L-1 BA plus 1000 mg.L-1 cefotaxime. The highest percentage of the shoot formation (100%) was recorded at 1 mg.L-1 BA plus 1000 mg.L-1 cefotaxime, while, it was relatively lower (75%) on than the medium containing 1.5 mg.L-1 BA in combination with 250 mg.L-1 cefotaxime. The highest root induction was observed in the medium containing 500 mg.L-1 cefotaxime + 0.1 mg.L-1 IAA. A significant positive influence on roots and leaves formation, as well as their number, in addition to regeneration of shoots was observed as well. CONCLUSIONS: This is the first work reporting an appropriate regeneration procedure for the melon, an Iranian native crop.