Regulation of related genes promoting resistant in Iris against root rot disease, Fusarium oxysporum f. sp. gladioli

Transcriptome-based analysis of candidate gene markers associated with resistance mechanism to Phytophthora melonis that causes root and crown rot in pumpkin

Root and crown rot incited by an oomycete, Phytophthora melonis , causes significant yield losses in commercial pumpkin (Cucurbita pepo ) production worldwide. Currently, resistant cultivars and knowledge of molecular mechanism of C. pepo against P. melonis are scarce. Here, we analysed the quantitative gene expression changes of 10 candidate gene markers (bHLH87, ERF014, HSF, MYB, PR-1, WRKY21, CPI, POD, PSK, SGT ) in pumpkin roots and leaves at three time points (h post-inoculation, hpi) following inoculation with P. melonis in two resistant (Ghelyani and Tanbal), and two susceptible (Marmari and Khoreshti) varieties of pumpkin. Gene expression using quantitative real time PCR along a time course revealed the strongest transcriptomic response at 48 and 72hpi in resistant genotypes, 1.1-2.7-fold in roots and leaves, respectively, with a high significant correlation (r =0.857**-0.974**). We also found that CPI , PSK, SGT1 and POD act as a dual regulator that similarly modulate immunity not only against P. melonis , but also against other diseases such as early blight (Alternaria cucumerina) , powdery mildew (Podosphaera xanthii ), downy mildews (Pseudoperonospora cubensis ), and pathogenic plant nematodes (Meloidogyne javanica ). Furthermore, significantly higher activities of the ROS scavenging defence enzymes, catalase (1.6-fold increase) and peroxidase (6-fold increase) were observed in the roots of resistant cultivars at different hpi compared with non-inoculated controls. In addition, the biomass growth parameters including leaf and root length, stem and root diameter, root fresh weight and volume were significantly different among studied genotypes. Cumulatively, the transcriptome data provide novel insights into the response of pumpkins for improving pumpkin breeding to P. melonis .

Co-inoculation of Mycorrhiza and methyl jasmonate regulates morpho-physiological and antioxidant responses of Crocus sativus (Saffron) under salinity stress conditions

Salinity stress is the second most devastating abiotic factor limiting plant growth and yields. Climate changes have significantly increased salinity levels of soil. Besides improving the physiological responses under stress conditions, jasmonates modulate Mycorrhiza-Plant relationships. The present study aimed to evaluate the effects of methyl jasmonate (MeJ) and Funneliformis mosseae (Arbuscular mycorrhizal (AM) on morphology and improving antioxidant mechanisms in Crocus sativus L. under salinity stress. After inoculation with AM, pre-treated C. sativus corms with MeJ were grown under low, moderate, and severe salinity stress. Intense salinity levels damaged the corm, root, total leaf dry weight, and area. Salinities up to 50 mM increased Proline content and Polyphenol oxidase (PPO) activity, but MeJ increased this trend in proline. Generally, MeJ increased anthocyanins, total soluble sugars, and PPO. Total chlorophyll and superoxide dismutase (SOD) activity increased by salinity. The maximum catalase and SOD activities in + MeJ + AM were 50 and 125 mM, respectively, and the maximum total chlorophyll in -MeJ + AM treatment was 75 mM. Although 20 and 50 mM increased plant growth, using mycorrhiza and jasmonate enhanced this trend. Moreover, these treatments reduced the damage of 75 and 100 mM salinity stress. Using MeJ and AM can improve the growth of saffron under various ranges of salinity stress levels; however, in severe levels like 120 mM, this phytohormone and F. mosseae effects on saffron could be adverse.

Transcriptome-based analysis of resistance mechanisms to Bipolaris sorokiniana, a common wheat root-rot disease

In common root and crown rot (CRR), Bipolaris sorokiniana (Sace.) is one of the important in wheat, causing considerable yield losses globally. Sources of resistance can provide a feasible and effective method of control for plant disease management. However, knowledge on mechanisms of resistance is scarce. We screened 33 wheat genotypes against B. sorokiniana under greenhouse and field conditions. In addition, real-time quantitative PCR (qPCR) analysis using ten novel candidate gene markers, Cre3, EDS1, LTP5, PGIP, PR-1, PIEP1, TLP, UGT, Stb6 and PFT, was conducted on leaves and roots, along with changes in activity of antioxidant enzymes, peroxidase, catalase, β-1,3-glucanase, and phenolic content for their involvement in disease impact mechanisms. Lowest disease severity was in 'Alvand', followed by 'Baharan' and 'Bam' as resistant genotypes. Quantitative gene expression showed that, although the candidate defence genes were upregulated 1.24- to 3.5-fold in wheat roots and leaves inoculated with B. sorokiniana, they were highly regulated in resistant varieties 'Alvand', 'Mehregan' and 'Bam'. Cre3, a resistance gene to cereal cyst nematode Heterodera filipjevi, was regulated in cultivars resistant to B. sorokiniana. Similar results were obtained for Stb6, a gene resistant to Septoria tritici blotch, EDS1 resistant to powdery mildew, Blumeria graminis, and the genes PR-1 and UGT resistant to leaf rust, Puccinia triticina. Antioxidant enzyme activity also showed the highest increases in resistant genotypes. In conclusion, the T. aestivum-B. sorokiniana interaction in resistant wheat cultivars uses defence-related genes and enzymes that protect wheat towards sustainable development. Further such studies will shed light on simultaneous resistance to other diseases in wheat cultivars.

Biochemical defense mechanism associated with host-specific disease resistance pathways against Rhizoctonia solani AG3-PT potatoes canker disease

Screening for resistance in 40 potato genotypes to Rhizoctonia solani AG-3PT-stem-canker, antioxidant enzymes activity as well as total phenol compounds were documented. Rhizoctonia solani AG-3PT-stem-canker is one of the most devastating diseases that leads to severe economic losses in potatoes, Solanum tuberosum globally. Crop management and eugenic practices, especially the use of resistance can be effective in reducing the disease incidence. However, the information about potato-R. Solani interaction is still limited. This study explored screening for resistance in forty potato genotypes to R. solani, analyzing biomass growth parameters (BGPs), as well as antioxidant enzymes activity of which peroxidase/peroxide-reductases (POXs), superoxide dismutase (SOD), polyphenol oxidase (PPO), catalase (CAT), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU) and total phenol compounds (TPCs) were taken into account. In addition, we analyzed up-regulation of two gene markers (PR-1 and Osmotin), using reverse transcription quantitative PCR (RT-qPCR). For which, the resistant 'Savalan', partially resistant 'Agria', partially susceptible 'Sagita' and susceptible 'Pashandi' were selected to explore the trails in their roots and leaves over the time courses of 1, 2 and 3-weeks post inoculation (wpi) following inoculation. Cluster analysis divided potatoes into four distinct groups, based on disease severity scales (0-100%) significance. The BGPs, shoot and root length, fresh and dry weight, and root volume were also significantly higher in infected potatoes compared to non-inoculated controls. Antioxidant enzymes activity also indicated the highest increased levels for POX (fourfold at 3wpi), CAT (1.5-fold at 3wpi), SOD (6.8-fold at 1wpi), and PAL (2.7-fold at 3wpi) in the resistant genotype, 'Savalan', whereas the highest activity was recorded in TPC (twofold at 1 wpi), PPO (threefold at 3wpi), and GLU (2.3-fold at 1wpi) in partially resistant genotypes. Although the defense-related enzymatic activities were sharply elevated in the resistant and partially resistant genotypes following inoculation, no significant correlations were between the activity trends of the related enzymes. The two related gene markers also showed comprehensive transcriptional responses up to 3.4-fold, predominantly in resistant genotypes. Surprisingly, the PR-1 gene marker, basically resistant to Wilting agent Verticillium dahlia was overexpressed in resistant 'Savalan' and 'Agria' against R. solani AG3-PT. Similar results were obtained on Osmotin gene marker resistant to late-blight P. infestans, and early-blight Alternaria solani that similarly modulates immunity against R. solani. Furthermore, there was a significant correlation between resistance, enzyme activity, and gene expression in the aforesaid cultivars. Studying the physiological metabolic pathways of antioxidant enzymes activity appears to be an important direction in research to elucidate resistance to R. solani in potatoes.

Identification of novel associations of candidate genes with resistance to Rhizoctonia solani AG-3PT in Solanum tuberosum stem canker

To develop an understanding mechanism to define responding of potatoes to R. solani, we analyzed the expression of ten novel candidate gene-markers using reverse-transcription-quantitative PCR (RT-qPCR) in resistant 'Savalan' and partially resistant 'Agria' in contrast to susceptible 'Sagita', and partially susceptible 'Pashandi'. In addition, oxidant-enzymatic-activity of catalase and superoxide-dismutase, as well as biomass-growth-parameters; shoot and root length, fresh and dry weight, and root volume were considered as complementary factors to the involving mechanism accordingly. Gene-markers up-regulated maximum up to 3.5-fold with the highest correlation, r = 0.939** following R. solani-inoculation, predominantly in resistant genotypes. Surprisingly, WRKY8-gene, basically resistant to late-blight-Phytophtora infestans was also up-regulated to 2.3-fold in resistant 'Savalan' followed by 'Agria'. Similar results with 3.1-fold were obtained on Osmotin-gene resistant to early-blight-Alternaria alternata. Enzymatic-activity of catalase with 1.6-fold and superoxide-dismutase, 6.8-fold also showed the highest level of activity in resistant genotypes, and had a high significant correlation, r = 773** and r = 0.881** with expression levels of related gene-markers respectively. Similarly, there were significant differences in biomass-growth-parameters, but with reductions in partially susceptible 'Sagita' and susceptible 'Pashandi'. Conclusively, S. tuberosum-R. solani interaction revealed that certain gene-markers can cover resistance to more than one disease simultaneously.

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), β-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.