β-1,3-Glucan with different degree of polymerization induced different defense responses in tobacco

► Curdlan is cheaper than laminaran so that β-1,3-glucan can be widely used in China. ► β-1,3-Glucan and chitosan oligosaccharides are recognized by different modes of perception in tobacco cells. ► Curdlan oligosaccharides and laminaran are able to induce nitric oxide burst mainly via nitric oxide synthase (NOS) pathway in tobacco cells. ► β-1,3-Glucan with low DP played a vital role in the rapid responses, whereas high DP β-1,3-glucan was responsible for the longer term effects.