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

In order to elucidate defense-inducing activities in tobacco, curdlan oligosaccharides (CRDO) with low degree of polymerization (DP) were prepared for comparison with high DP Laminaran (Lam). Fast response defenses such as extracellular pH shift, hydrogen peroxide (H2O2) production, nitric oxide (NO) release and stomatal movement under light as well as the protection against tobacco mosaic virus (TMV) were performed. CRDO triggered faster extracellular alkalinization than Lam. Refractory states analysis showed there were different perception modes between β-1,3-glucan and chitosan oligosaccharides (COS). Elicitors induced cells to generate NO probably via the nitric oxide synthase (NOS) pathway. Moreover, CRDO exhibited more intensive in stomatal movement than Lam. However, protection against TMV implied Lam played a longer term role in defense responses than CRDO. Therefore, we concluded 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.