Compatibility Evaluation and Anatomical Observation of Melon Grafted Onto Eight Cucurbitaceae Species

Abstract

Melon (Cucumis melo) is one of the top 10 fruits in the world, and its production often suffers due to soil-borne diseases. Grafting is an effective way to solve this problem. However, graft incompatibility between scion and rootstock limits the application of melon grafting. In this study, the melon was grafted onto eight Cucurbitaceae species (cucumber, pumpkin, melon, luffa, wax gourd, bottle gourd, bitter gourd, and watermelon), and graft compatibility evaluation and anatomical observation were conducted. Taking melon homo-grafted plants as control, melon grafted onto cucumber and pumpkin rootstocks was compatible, while melon grafted onto luffa, wax gourd, bottle gourd, bitter gourd, and watermelon rootstocks was incompatible based on the scion dry weight on day 42 after grafting. Meanwhile, we found that starch–iodine staining of scion stem base is an index to predict graft compatibility earlier, on day 14 after grafting. Further, microsection observations showed that there was more cell proliferation at graft junction of melon hetero-grafted combinations; vascular reconnection occurred in all graft combinations. However, excess callose deposited at graft junction resulted in the blockage of photosynthate transport, thus, leading to starch accumulation in scion stem base, and finally graft incompatibility. In addition, undegraded necrotic layer fragments were observed at graft junctions of melon grafted onto incompatible bitter gourd and watermelon rootstocks. The above results provide clues for the selection and breeding of compatible Cucurbitaceae rootstocks of melon and demonstrate that starch accumulation in scion base and callose deposition at graft junction is associated with melon graft compatibility.

Scions impact biomass allocation and root enzymatic activity of rootstocks in grafted melon and watermelon plants

“…Thus, while the entire plant growth was limited in M/Ls, this was particularly true for the root system, resulting in a dramatically reduced biomass allocation—which will have increasingly hampered water and nutrient supply to disproportionally growing shoots. Incompatibility issues between melon and bottle gourd ( L. siceraria ) were reported earlier ( Xiong et al., 2021 ) and are confirmed by the findings of this experiment. Interestingly, both watermelon and melon scions have fostered root growth of CC versus the aboveground part, whereas no effect (watermelon) or a deleterious effect (melon) was found for the Ls root system.…”

“…Together, this indicates that some degree of incompatibility exists between specific graft components. The incompatibility between rootstock and scion species is frequently explained by the presence of a necrotic layer at the graft junction and discontinuity in the vascular bundles at the graft union ( Kawaguchi et al., 2008 ; Xu et al., 2015 ; Xiong et al., 2021 ), low level of antioxidant enzyme activities and high level of reactive oxygen species at the rootstock–scion interface ( Aloni et al., 2008 ), the impairment of assimilate transport ( Camalle et al., 2021 ; Xiong et al., 2021 ), and hormone synthesis and signaling ( Camalle et al., 2021 ).…”

Comparisons of Anatomical Characteristics and Transcriptomic Differences between Heterografts and Homografts in Pyrus L.

“…Cellulose is also a major component of plant cell walls and is responsible for oriented cell elongation during growth and development [ 48 ]. The gene PbBglu13 is involved in β-glucosidase synthesis, which is a cellulase that produces glucose by decomposing cellobiose, a hydrolysate of cellulose glucanase [ 9 , 49 , 50 ]. The expression of PbBglu13 was higher in heterografts than in homografts in the process of the grafting junction ( Figure 6 b).…”

“…Although there might be great differences in grafting between different species, the connective tissue between rootstock and scion is the basis of successful grafting [ 7 ]. However, grafting incompatibility often occurs in heterografts, leading to low rates of survival, abnormal growth, and physiological disorders [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Graft incompatibility occurs in a variety of horticultural species.…”

Increasing the yield of melon in a greenhouse at vegetative grafting on vegetable marrow rootstocks

“…Исследования показали, что дыня, привитая к восьми видам Cucurbitaceae (огурец, тыква, дыня, люффа, восковая тыква, бутылочная тыква, горькая тыква и арбуз) показала различную степень совместимости прививки. Дыня, привитая на подвои огурца и тыквы, имела наилучшие показатели привоя на 42-й день после прививки [12].…”