植物科学

Bacteria blight diseases of rice due to several genera of pathogenic bacteria are one of the major constraints worldwide for rice production. The disease can be best managed through host plant resistance sources. For most of these bacteria such as Xanthomonas oryzae pv. oryzae, X. oryzae pv. oryzicola, Pseudomonas fuscovaginae, Burkholderia glumae, Burkholderia gladioli and Acidovorax avenae subsp. avenae, specific diagnostic techniques that include molecular and pathogenicity tests have been developed.

However, for Pantoea spp., information on pathogenicity assay is very limited and protocols used are not uniform. Most authors use the leaf clipping method. In this paper, we describe the protocol for mechanical inoculation of rice seedlings aged 35 days. The method consists of infiltrating bacterial suspensions at concentrations of 10⁸ CFU/ml, with a needleless syringe into the intercellular and interveinal spaces of rice leaves underside at about 4-5 cm below the leaf tip.

This method can be used for a standardized pathogenicity assessment, germplasm resistance evaluation for identifying and characterizing resistance sources.

Quantification of insect damage is an essential measurement for identifying resistance in plants. In screening for host plant resistance against thrips, the total damaged leaf area is used as a criterion to determine resistance levels. Here we present an objective novel method for analyzing thrips damage on leaf disc using the freely available software programs Ilastik and ImageJ. The protocol was developed in order to screen over 40 Capsicum lines for resistance against Frankliniella occidentalis (Western Flower Thrips) and Thrips tabaci (Onion thrips).

Cuscuta spp. are widespread obligate holoparasitic plants with a broad host spectrum. Rootless Cuscuta penetrates host stems with so called haustoria to form a direct connection to the host vascular tissue (Dawson et al., 1994; Lanini and Kogan, 2005; Kaiser et al., 2015). This connection allows a steady uptake of water, assimilates and essential nutrients from the host plant and therefore enables Cuscuta growth and proliferation. To quantify the parasites’ ability to grow on potential host plants one can use the quantitative growth assay (Hegenauer et al., 2016) described herein, which exclusively utilizes fresh weight measurement as readout.

This assay can be used to rapidly and accurately quantify levels of leaf necrosis induced after transient expression of R genes and elicitor combinations (Harris et al., 2013). It is based on the inverse correlation between level of necrosis and chlorophyll content in leaf tissue. It is adapted from the calculations described by (Strain et al., 1971).