Liu Yu-Xiao,Han Wen-Hao,Wang Jun-Xia,Zhang Feng-Bin,Ji Shun-Xia,Zhong Yu-Wei,Liu Shu-Sheng,Wang Xiao-Wei
Plants face an array of insect herbivores and have evolved complex defense approaches against various insect feeding strategies. However, little is known about how plants respond to successive attacks by herbivores with different feeding modes and coordinate their diverse defense mechanisms. In this study, we unveil that inducible jasmonic acid (JA) accumulation in response to leaf-chewing insects augments plant resistance and repellence to sequential leaf-chewing insect (caterpillar) and phloem-feeding insect (whitefly) infestations. Conversely, constitutive and whitefly inducible salicylic acid (SA) accumulation exclusively bolsters defense against later-stage whitefly invasion. Through assessments of herbivore performance and preferences on wild-type, JA-deficient, and SA-deficient plants, we show that JA/SA levels regulate plant resistance to both initial and sequential herbivores. Notably, JA or SA accumulation due to caterpillar or whitefly attacks does not substantially affect constitutive levels of the other compound, despite their antagonistic crosstalk. Furthermore, exogenous JA application in tobacco elicits efficient defense against successive caterpillar and whitefly assaults, surpassing SA's efficacy, albeit with associated growth penalties. Our discoveries demonstrate that plants can tailor their defense strategies against initial and sequential insects with different feeding modes. This customized defense is facilitated by JA/SA responses and their intricate cross-talk while taking account of the growth-defense trade-off.
Yunjing Wang,Qian Gong,Fan Huang,Linfang He,Yule Liu
Summary Wounding evokes transient increases in cytosolic calcium (Ca 2+ ) concentration. Visualizing real-time Ca 2+ flux provides new insights into Ca 2+ -signaling pathways. Here, we outline a protocol to detect insect feeding-induced Ca 2+ flux elevation in Nicotiana benthamiana leaves based on the GCaMP3 reporter system by Leica fluorescence stereo microscopes (LFSM). LFSM combines super-fast manual screening with high-end imaging capabilities. Through this protocol, we can clearly observe the calcium flow after aphid’s piercing-sucking. Additionally, we describe a protocol to quantify Ca 2+ level using LFSM. For complete details on the use and execution of this protocol, please refer to Wang et al. (2021) .
Lymantria xylina is the most important defoliator, damaging the effective coastal windbreak tree species Casuarina equisetifolia . However, the underlying genetic mechanisms through which C . equisetifolia responds to L . xylina attacks remain unknown. Here, we compared the transcriptional, phytohormone and metabolic differences between susceptible (S) and resistant (R) C . equisetifolia cultivars in response to L . xylina feeding. The main L . xylina -induced resistance in C . equisetifolia was a jasmonate (JA) response and JA synthesis was highly induced by L . xylina feeding at both the transcriptional and metabolic levels, thus promoting flavonoid accumulation. The JA response was highly activated by L . xylina feeding on the R but not in the S cultivar, although the JA signalling pathway was intact in both cultivars. We found a single amino acid mutation in the homologues of glutamate receptor-like protein 3.6 (CeGLR3.6 T807I ) in the S cultivar. Compared with the GLR3.6 homologues in the R cultivar, phosphorylation of CeGLR3.6 T807I was not induced by insect feeding, leading to a decreased JA response in the S cultivar. Collectively, this study provides new insights into the function of CeGLR3.6 in regulating the JA response of C . equisetifolia to L . xylina feeding.
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