ARTICLE | doi:10.20944/preprints202009.0682.v2
Online: 29 September 2020 (08:54:26 CEST)
Polyploid seeds production is laborious, complicated, and costly work. Tetraploid and triploid plants produce a fewer number of seeds/fruit, and triploid embryos are fairly weak, covered with a more hardened seed coat as compared to diploid seeds. Here we investigated the interactive effect of new grafting technique of polyploid watermelon scion onto rootstock on plants' survival rate, biochemical, and hormones contents. In this study, three different branches, apical meristem (AM), branch with 1 node (1N), and 2 nodes (2N) from di, Tri, and tetraploid watermelon plants, were used as scion and grafted onto squash rootstock. The results showed highly significant differences between polypoid watermelon when 1N using as a scion, tetraploid showed maximum survival rates, higher contents of hormones, and antioxidants (AOX) activities, compared to diploid, these may be the possible reasons for high compatibility in tetraploid and degrading the grafting zone in diploid. RTq-PCR results confirm that the expression of genes linked to compatibility is consistent with the hormonal and AOX activities. This study provides an alternative and economical approach to produce more tetraploid and triploid plants for breeding or seeds production by using branches as scions.
ARTICLE | doi:10.20944/preprints202012.0050.v1
Subject: Biology, Anatomy & Morphology Keywords: watermelon; polyploidy; grafting; branches; compatibility
Online: 2 December 2020 (08:07:11 CET)
Polyploid seed production is complicated, and costly work, produce a fewer number of seeds/fruits as compared to diploid seeds. Here we investigated the interactive effect of a new grafting technique of polyploid watermelon scion onto rootstock on plants' survival rate. In this study, three different branches, apical meristem (AM), branch with 1 node (1N), and 2 nodes (2N) from di, tri, and tetraploid watermelon plants, were used as scion and grafted onto squash rootstock. The results showed highly significant differences between polypoid watermelon when 1N was used as a scion. Tetraploid showed maximum survival rates, higher contents of hormones, carbohydrates, and antioxidants activities, compared to diploid. Here, we also performed applied sucrose exogenously, on the rootstocks seedlings before grafting to enhance survival rates. Significant survival rates were observed in the case of 2% sucrose application in all polyploids when 1N was used as a scion. RTq-PCR results confirm that the expression of genes linked to compatibility is consistent with the carbohydrates, hormonal and antioxidants activities. This study provides an alternative and economical approach to produce more tetraploid and triploid plants for breeding and seed production by using branches as scions, furthermore, provides more understanding of graft compatibility.
ARTICLE | doi:10.20944/preprints202208.0291.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Induced resistance; Watermelon; Fusarium; Root-knot nematode; Micronutrients
Online: 16 August 2022 (11:59:40 CEST)
The soil-borne pathogens, particularly Fusarium oxysporum f. sp. niveum (FON) and southern root-knot nematode (RKN, Meloidogyne incognita) are the major threat to watermelon production in the south-eastern United States. The role of soil micronutrients on induced resistance (IR) to plant diseases is well-documented in soil-based mediums. However, soil-based mediums limit the determination of the role(s) of individual micronutrients in IR. In this manuscript, we utilized hydroponics to assess the effect of controlled application of micronutrient, including iron (Fe), manganese (Mn), and zinc (Zn) on the expression of some IR genes (PR1, PR5, and NPR1 from salicylic acid (SA) pathway, and VSP, PDF, and LOX genes from jasmonic acid (JA) pathway) in watermelon seedlings upon inoculation with either FON or RKN or both. Plants were treated with higher (3X) or lower (0.5X) concentrations of micronutrients in Steiner solution (X= standard dose of micronutrient) for 7 days in a hydroponics system under greenhouse conditions. A subset of micronutrient-treated plants was inoculated (on the 8th day of micronutrient application) with FON and RKN (single and mixed). The expression of the IR genes in treated and control samples were evaluated using qRT-PCR. Although, significant phenotypic differences were not observed with respect to the severity of wilt symptoms or RKN galling with any of the micro-nutrient treatments within the 30 day-experimental-period, differences in the induction of IR genes were observed. However, the level of gene expression varied with sampling period, type and concentration of micro-nutrients ap-plied, and pathogen-inoculation. In the absence of pathogens, no significant changes were observed in the expression level of IR genes on 7th day of micronutrient treatment. However, pathogen inoculation affected the expression levels of the IR genes at 3-day post-inoculation. In FON inoculated plants, PDF was upregulated in high Fe treatment, whereas in RKN inoculated plants, low Mn treatment resulted in up-regulation of VSP. In the case of mixed inoculation with FON and RKN, the plants with low Zn treatment resulted in the upregulation of PR1. These observations suggest that the type and concentration of micronutrients in watermelon may potentially induce systemic resistance against FON and RKN through SA and JA pathways.