Plant polysaccharides are widely found in nature and have a variety of biological activities, including immunomodulatory, antioxidative, and antitumoral. Due to their low toxicity and easy absorption, they are widely used in the health food and pharmaceutical industries. However, low activity hinders the wide application. Chemical modification is an important method to improve plant polysaccharides’ physical and chemical properties. Through chemical modification, the antioxidant and immunomodulatory abilities of polysaccharides were significantly improved. Some polysaccharides with poor water solubility also significantly improved their water solubility after modification. Chemical modification of plant polysaccharides has become an important research direction. Research on the modification of plant polysaccharides is currently increasing, but a review of the various modification studies is absent. This paper reviews the research progress of chemical modification (sulfation, phosphorylation, acetylation, selenization, and carboxymethylation modification) of land plant polysaccharides (excluding marine plant polysaccharides and fungi plant polysaccharides) during the period of January 2012–June 2022, including the preparation, characterization, and biological activity of modified polysaccharides. This study will provide a basis for the deep application of land plant polysaccharides in food, nutraceuticals, and pharmaceuticals.

Alfalfa polysaccharides (AP) receive wide attention in the field of medicine, because of their anti-inflammatory property. However, AP has high molecular weight and poor water solubility, resulting in low biological activity. We wanted to obtain highly bioactive alfalfa polysaccharides for further research. Herein, we successfully synthesized highly substituted sulfated alfalfa polysaccharides (SAP) via the chlorosulfonic acid (CSA)-pyridine (Pyr) method, which was optimized using response surface methodology (RSM). Under the best reaction conditions, that is, the reaction temperature, time, and ratio of CSA to Pyr being 55 °C, 2.25 h, and 1.5:1, respectively, the maximum degree of substitution of SAP can reach up to 0.724. Fourier transform infrared spectroscopy also confirmed the existence of sulfonic acid groups on SAP. Despite the increased average molecular weight of SAP, its water solubility is improved, which is beneficial for its biological activity. Further in vitro results showed that SAP exhibited better antioxidant activity and antibacterial ability than AP. Besides, the former can efficiently enhance the viability of oxidatively stressed intestinal epithelial cells compared with the latter. Furthermore, SAP has the potential to inhibit obesity. It is concluded that sulfation modification could improve the antioxidant, antibacterial, bovine intestinal epithelial cells’ proliferation-promoting, and the obesity inhibition abilities of AP. The improvement of AP biological activity may provide references for the utilization of plant extracts that have weaker biological activity.

While previous studies have shown camelina drought tolerance relative to other oilseed crops, drought has been documented to severely influence the productivity of camelina. To date, little information is available on the drought tolerance of camelina genotypes. This study was conducted to evaluate drought tolerance in fifteen camelina genotypes and test the alleviative effect of nanoparticles on PEG-induced water deficit stress (WDS) at the whole-plant level at the Yangzhou University Pratacultural Science Experimental Station in September 2021. Four different degrees of WDS were induced by a range of PEG solution concentrations (0, 16.7, 25.0, 37.5, and 56.3 mM). A petri dish study determined that CamK8 and CamK9 (GR₅₀ = 19.0 and 34.3 mM, respectively) were the most sensitive and tolerant genotypes, respectively, to PEG-induced WDS. Results from the whole-plant test showed that the foliar application of MWCNTs (dose: 50 or 100 mg L⁻¹) or nano-Se (dose: 5 or 10 mg L⁻¹) alleviated the adverse effect of PEG-induced WDS, and increased the camelina plant height (ranges: 51.1–56.3 cm) and crop yield (ranges: 0.11–0.14 g plant⁻¹) compared with untreated control and PEG-treated plants (height: 43.5–56.9 cm; yield: 0.06–0.12 g plant⁻¹) in CamK8 without affecting the principal fatty acid composition and groups in camelina oil. The results of this study demonstrated that applying MWCNTs or nano-Se could alleviate WDS and maintain seed yield in camelina, providing the possibility of using these nanoparticles to manage WDS in agricultural practices.

Weed management has been one of the major challenges in camelina [Camelina sativa (L.) Crantz] production owing to the limited options for selective herbicides. The aim of this study was to evaluate and screen camelina-safe herbicides and establish an effective weed management program combining pre- and post-emergence herbicide application in camelina. There were 22 herbicides (6 herbicides registered as pre- and 16 herbicides registered as post-emergence herbicides) with various modes of action tested in this study. Greenhouse evaluation showed that, of the 22 herbicides tested, post-application of s-metolachlor and prodiamine (registered as pre-emergence herbicide), and clethodim, fluazifop-p, clopyralid, and quinclorac (registered as post-emergence herbicide) possessed adequate safety (~×4 of recommended doses) when used on the two camelina genotypes (CamC1 and CamK3) by evaluation of plant visual efficacy, seed weight, and plant biomass yield per plant. Herbicides from the ALS (e.g., flumetsulam), HPPD (e.g., mesotrione), IPP (e.g., clomazone), PPO (e.g., oxyfluorfen), and PS II (e.g., bentazon) groups caused severe camelina growth suppression and mortality. Field evaluation with greenhouse-selected herbicides demonstrated the superior weed control efficacy of sequential application combining pre- (s-metolachlor) and post-emergence (clethodim, fluazifop-p, or clopyralid) herbicides (84–90% reduction in weed biomass in camelina plots relative to untreated control) than the single application of those herbicides (68–83%). Clethodim and fluazifop-p provided good post-emerged grass weed control (e.g., crabgrass), whereas clopyralid effectively controlled the broadleaf weeds, such as common vetch and shepherd’s purse. Camelina seed yields from s-metolachlor following clethodim, fluazifop-p, or clopyralid application were statistically comparable to the yield of the weed-free treatment (hand weeding) and were significantly greater than those of the untreated control, indicating the effective weed control efficacies provided by those herbicides. Sequential application of the above herbicides did not affect camelina seed oil content, the principal UFA concentrations (e.g., C18:1~3), UFA/SFA, and MUFA/PUFA. In summary, sequential application combining pre- (s-metolachlor) and post-emergence (clethodim, fluazifop-p, or clopyralid) herbicides shows effective weed control in camelina, thus providing a great opportunity to increase camelina production through herbicide-based weed management.